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Summary Requirements

Core Theme: This video series teaches Java programming fundamentals, starting with setting up the development environment (JDK and IDE) and progressing through basic syntax, variables, control flow (if/else, switches), loops (while, for), methods, arrays, strings, exception handling, file I/O, and object-oriented programming concepts like inheritance, polymorphism, and encapsulation. It culminates in building practical projects like a calculator, a number guessing game, a shopping cart, a compound interest calculator, a weight converter, a simple banking application, a dice rolling game, a slot machine, a countdown timer, an alarm clock with music, and a basic Hangman game.
Key Points:
- Environment Setup: Essential tools like JDK and IDE (IntelliJ) are covered for starting Java development.

Mind Map

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คลิกเพื่อสำรวจ Mind Map แบบอินเตอร์แอคทีฟฉบับเต็ม

hey how's it going everybody in this

video I'm going to teach you everything

you need to know to start coding with

Java this series even contains about 15

Hands-On projects that we're going to

code together our final project will be

a functioning alarm clock that plays

music of your choice if you've never

coded anything in your life don't worry

we're going to start from the very

beginning I encourage you to sit back

show I don't like boring introductions

so we're just going to Jump Right In to

start coding with Java you'll need two

things a Java development kit also known

as a jdk a jdk contains a compiler a

compiler will compile your source code

your written code into bite code which

can run on a machine you'll also need an

integrated development environment IDE

an IDE is a fancy term for a workspace

in which we can write code because

sometimes notepad just doesn't cut it

we'll get started by downloading a jdk a

Java development kit okay here's how to

download the jdk the Java development

kit you can easily just Google or do a

search for jdk download we're going to

use the one by Oracle so we'll click on

this link I'll also post the link in the

description of this video if you would

like to access it that way we will

download the latest jdk version as of

the filming of this video we're on jdk

23 we're going to look for our operating

system I'm running Windows I will

download the 64- bit installer by

clicking this

download the download is complete we're

going to open this

next our jdk has been successfully

installed we can close it and that's all

we got to do for the

jdk now we need to install an IDE an

integrated development

environment one I recommend is intellig

you can easily just Google or do a

search for intellig

download we'll select the top

link now if you're not brought to this

page let's say you're at a different

page go to the top right where it says

get intellig click it and you should be

brought to a download page this version

is a 30-day trial but if you scroll down

there is a free version this is the

Community Edition because I don't like

to pay for things select the correct

download for your operating system I'm

executable once the download is complete

we will open this executable for

intellig select

next choose a destination folder I'll

keep it as is Click

next you can create a desktop shortcut I

now this is important too you can update

the path variable it basically tells

your operating system where to find the

executable files this is useful if

you're going to be running Java code

from command prompt or terminal but we

won't be doing that in this series you

can always come back later and update

install all right and we can finish we

might as well start intellig right away

I'm going to check this check boox to

run intellig and

finish we should now be at a welcome

screen for intellig we need to create a

project select new project I'll name my

project my first

project select the latest version of

your jdk I have jdk version 23 there is

a checkbox and it's most likely going to

be checked that says add sample code

just as a beginner I recommend

unchecking this it'll autogenerate some

sample code for us but we're going to do

that ourselves I'll show you how and then

then

create within our project folder

navigate to your Source folder it has a

name of

SRC we need to create a main Java file

go to the top toolbar go to file new

Java class we'll name this class main

it's going to contain the main body of

our code then select class

now the font is probably going to be really

really

small here's how to change

that go to the top toolbar go to

settings go to editor

editor

General and you can check this checkbox

for change font size with Control Plus

Mouse wheel apply okay now you should be

able to zoom in if you hold control and

scroll your mouse wheel now we can

actually read something in Java in order

to get some code to run you need a main

method within our class of main there's

a set of curly braces we'll type the

following public static void main add a

set of parentheses then a set of curly

braces within the set of parentheses

you're going to type the following

string straight brackets

args like you're a pirate

you need this method in order for your

program to run over the course of this

series we'll learn what each of these

keywords means but as a beginner think

of it as a magic spell that you have to

say in order to get your program to run

to run your program you're going to

click the screen Arrow or you can hold

F10 if we have written the main method

successfully we should have no

errors it says processed finished with

exit code zero that means everything is

running fine if I were to delete this

main method we can't actually run the

program so be sure that that method is

in to Output some text to the console

window we're going to type system with a

capital s. out. print add a set of

parentheses then a

semicolon in Java you'll end most of

your statements with a semicolon it's

kind of like a period at the end of a

sentence in the English language

within the set of parentheses we'll add

a set of double quotes whatever we would

like to Output we're going to type

within the set of double quotes think of

a food you like I'll type I like

pizza and then we can run this and this

should be the

output again I'm going to go to the

Green Arrow or you can hold shift

F10 and a console window should pop up

that says I like pizza or whatever your

here let's add another line of

system.out.print end it with the

semicolon within quotes which we type I

like pizza it's really

good let's run it

again all right here's our output I like

pizza it's really good

now these are both on the same line to

move your output down to the next line

you can use print Ln meaning print

line now it should look something like

good if you type back sln that's an

escape sequence for a new line and that

works too besides print line I like

pizza it's really good

let's add another line of text

system.out.print or print

line I like pizza it's really good buy me

character I like pizza it's really good

buy me

pizza or again you could use print

thing now you can write a comment

comments aren't displayed as output to

write a comment you use two forward

slashes and the text should be gray out

comments are good as notes for yourself

or for other developers let's add a

comment that this is my first Java

program when we run this this won't

display us out output it's really just

used as notes we still have our output

it hasn't

changed you can even add a multi-line

comment with a forward slash then an

asterisk to end a multi-line comment you

need an asterisk then a forward slash

I'll write this is a

multi- line

comment this won't output either

we don't see either of these

comments this is specific for intellig

but you can change the console font and

the colors I kind of find this hard to

read to do that we're going to go to the

top menu under file go to

settings under color scheme go to

console font here you can change the

font if you would like or the colors

I'll change the colors I'll make the

output bright green so it's easier to

read I'll go to console

standard output and select a new color

I'll select something

green apply and I think that looks

pretty good it's more readable that way

I'll also change the system output

too I'll make it kind of gray out that's pretty

pretty

good yeah and there's our output I like

pizza it's really good buy me

pizza now a shortcut to type system. out

at print line if you're using intellig

is to type s o u t then hit tab that's

going to autogenerate a print line

statement for you I didn't realize this

trick until a little bit later so you

don't always need to type out this

statement you can just autogenerate it

all right everybody and that is your

first Java program your homework in the

comment section is to post three print

line statements maybe type A poem or

some song lyrics or something and well

everybody that is your first Java program

all right everybody so we are moving on

to variables in Java probably back in

elementary school or middle school you

learned about variables in algebra a

variable was a representation of a

number well in programming we have

variables too a variable is a reusable

container for a value a variable behaves

as if it was the value it contains but

variables can contain more than just

numbers they can contain characters and

even entire words there's different data

types a whole number would be an integer

a number that includes a decimal would

be a double there's two categories of

variables we'll discuss primitive and

reference primitive variables are simple

values like numbers they're stored

directly in memory usually in a location

known as the stack reference variables

actually hold memory addresses on the

stack they point to a location in a

different area known as the Heap think

of it this way if I give you a primitive

variable that would be the same as me

handing you

$10 but if I give you a reference

variable a memory address that would be

the same as me giving you an IOU that

says I owe you $10 but the actual money

I owe you is at the bank that might be a

beginner's way of thinking of the

difference between a primitive and

reference data type primitive I'm giving

you $10 a reference data type I'm giving

you an IOU that I owe you $10 we'll

discuss the different data types we'll

begin with integers an INT short for

integer is a primitive data type I'll

show you how we can create an integer

variable in Java there's two steps to

creating a variable the first is

declaration the second is assignment

let's say we would like to create a

variable that stores a whole number an

integer with the first step of

Declaration we're going to first type

the data type of what we would like to

store exactly so for integers we will

type int then we should think of a

unique variable name we don't want to

say X or something similar that would

make sense in basic algebra but in

programming you want your variables to

be descriptive like shut up in

programming you want your variables to

be descriptive so let's say we are

working with let's say in age end this

line with a semicolon so this is

declaration step one we are creating a

variable named age if I was to print my

variable of age system.out.print

system.out.print

is variable age might not have been

initialized we're using a variable but

we've never given it a value we've never

completed step two of

assignment so we can set age equal to a

value so on my YouTube channel the

average age of my viewers is

approximately 21 or so so let's set age

to be 21 and then we'll print

it so that outputs 21 if I were to

change this to

30 then my variable age would behave as

if it was the number 30 so those are

integers they're whole numbers let's say

that I'm

30.5 let's see what happens exactly you

can see that intellig is already giving

us a warning that we're working with a

different data type known as doubles so

if I were to run this we get an error

message we have incompatible types from

double to in if we declare a variable as

an integer they can only store whole

integers let's think of a few more

examples another example of an integer

could be a year so let's say the year is 2025

2025

then we'll print our year

year

2025 or maybe a quantity int

quantity equals

1 then we'll print our

quantity one so in working with

quantities they're whole numbers usually

right we wouldn't have let's say half a

product 1.5 I would like 1.5 Nintendo

switches that wouldn't make sense right

they would would be whole numbers like

two now you can output a variable with a

string of text as

well let's say the year

is then I'll add plus a variable year

make sure that the variable is not within

within

quotes So currently this says the year is

2025 you do have to pay attention to the

spacing so after the word is I'm going

to add a space to separate is and the variable

variable

year the year is

2025 now if our variable was within

quotes we would literally be printing

the word year the year is year so don't

do that unless it's

intentional let's go on to the next data

type the next data type is double double

is a number but it can contain a decimal

portion unlike int ins are whole

numbers so this time we will create a

variable type of double what are some

examples of a variable that could be a

double let's say a price there could be

$19.99 or perhaps a GPA a grade point

3.5 or a temperature

double temperature equals

12.5 all right let's output some of

these let's do Price

Price system.out.print

system.out.print

price

19.99 let's add a unit of currency I'll

so Dollar Sign Plus price

$19.99 if you were to assign a variable

that's a double data type but store an

integer here's what would

happen we would just add 0 Z to the end

it's still a double so those are doubles

they're numbers that can contain a

decimal portion unlike

integers okay then the next data type we

have is charart

meaning character Char pronounced like

the word

Charizard so with chars what are a few

examples of single characters we could

use let's say a grade like a letter

grade with chars characters we enclose

them within single quotes let's say we

have the letter A that's the grade we

got on the last test or

maybe I'll put an exclamation point or

something or currency Char currency

equals pick a unit of currency I'll pick

dollars okay then let's output some of these

these system.out.print

system.out.print

grade which is an

A or our symbol

an exclamation point or our

currency which is American

dollars so then we have something called

booleans booleans are either true or

false we will declare this variable as a

Boolean let's check to see if somebody

is a student our variable name will be

is student and this equals true or false

so if I am a student I would say true

now a common naming convention in Java

is called camel case naming convention

if your variable name takes up two words

such as is and student when you combine

them the first letter of the first word

should be lowercase then any word after

the first letter is going to be

uppercase so is student and I will set

that to be true maybe something is for

sale or not Boolean for sale equals

false it's not for sale is somebody

online Boolean is online now I will set

that to be true these are a few examples

of Boolean

variables now you could output them

directly using system.out.print line

Let's test it system.out.print line

let's output is student

are we a student that is true is

something for sale for

sale that is false now with Boolean

variables we don't typically output them

directly to the console we tend to use

them more internally within a

program one place in which you might see

them is with the use of if statements

and this is a future topic we'll revisit

it later but I want to demonstrate the

usefulness of booleans so this is an if

statement we can check some condition

parenthesis then curly

braces if our condition is true if is

student double equals true but we could

simplify this

to if is student if this variable

contains true which it does we can

execute some code system.out.print

system.out.print

line we will print the following

you are a

student if this Boolean variable

contains true we will print the

following you are a

student or we could add else an else

Clause else let's

print you are not a

student So currently we're still a

student but if this Boolean variable

contained a value of false we would

perform form the else

statement you are not a student so we'll

cover if statements in a future topic

you don't necessarily need to know how

these work right now but that's one of

the uses of booleans they can only

contain true or

false these are a few of the basic

primitive data types for beginners int

for integers they contain whole numbers

doubles are numbers but they can contain

a decimal chars meaning characters are

single characters and booleans which are

either true or false these are a few of

the beginner primitive data types but

there's still a lot more than this

there's floats there's long doubles all

sorts of different data types but you

don't need to know those as a beginner I

would just stick to these four for now

so then we have the reference data types

A few of which include strings arrays

and objects in this topic we're only

going to discuss strings a series of

characters phas and objects are really

complex we'll revisit these later so

we're going to create a string a series of

characters so the data type is going to

be string an example of a series of

characters could be a name what's your

name with strings we enclose them within

double quotes chars single characters

are single quotes it's really easy to

mix the two up you might do it a few

times as a beginner so type in your name

in including a space I'll use my YouTube channel

channel

name and then we will output our name

name and your first and last name should

appear now we could use this variable of

name within another string this is known

as string

concatenation so let's say

say

hello plus our name

hello bro code or whatever your name is

what are a few other examples of strings

we could

write let's add string food

equals again within a set of double

quotes add your favorite food mine is

pizza then let's type again system.out.print

line your favorite food is

plus the variable

pizza what about an email string email

equals make up an email fake1 123@gmail.com

strings they can contain numbers but we

treat them more as characters rather

than actual numbers that we can use for

any sort of math or

arithmetic so let's print our email your email

or what about a

car string

car think of a car that you like I will

pick a Mustang that's another example of

a string or a color

string color equals

red so strings are a series of

characters they have a reference data

type you may have also noticed that the

font color of strings is different from

the primitive data types too of booleans

chars doubles and Ins at least within my

workspace the font color is orange and

with strings the font color of these

data types is white now we're going to

cover a few exercises

so let's start with our name

system.out.print line we will print

hello plus our name variable it's a

string hello your first and last

name let's print our age system.out.print

system.out.print

line u

r we're going to insert our variable age

then add another string another string

literal you are age years old again do

pay attention to the

spacing you are 30 years

old let's use my

GPA that's a

line your GPA

is then we will insert our GPA

your GPA is

grade system.out.print

line your average letter grade

is our variable

grade your average letter grade is is a

now within a single print line statement

we're going to combine multiple

variables let's say we're going to

Output our

color a

year and our

car all within one print statement system.out.print

system.out.print

line let's say we're choosing a car your

choice is a We'll add our color variable

plus the

year plus our car let's see what happens

exactly if we attempt

this so we've combined all three

variables red 2025 and our car of

Mustang so we're going to add some space

characters between each to separate them

so plus a space character add that after the

the

color after the

year we'll add a space between color and

year and year and

car so your choice is a red 2025

Mustang let's display the

price system.out.print

is plus currency

I picked American

price the price is

$9.99 uh for a car let's up that that's

way too cheap that's too good to be true

99 that's more

realistic now we're going to use this

Boolean variable of for

sale if

for sale if this is true then we're

print there is

a plus

Car Plus the text of for

sale else we will print something else

let's say

the plus Car Plus is not for sale for sale

sale

currently that's set to false the

true there is a Mustang for sale for

sale is set to true all right everybody

so those are variables in Java a

variable is a reusable container for a

value a variable behaves as if it was

the value that it contains there's two

different categories of variables

primitive and reference primitive data

types are simple values like integers

floats single characters and

booleans they're stored directly in

memory usually in a location known as

the stack reference variables such as

strings which are a series of characters

like your name or an email they're more

complicated we store a memory address

that points to a location in the Heap

and your homework assignment is in the

comment section post five variables a

string an integer a double A Char and a

Boolean and if you don't do your

homework you're going to make me sad and

well everybody that is an introduction

Java hello again friends so today I'm

going to show you how we can accept user

input in Java we will need the help of

what is called a scanner a scanner is an

object that allows us to accept user

input in Java however in order to use a

scanner we actually need to import it

from the certain package called

utilities or util at the top of our Java

file we're going to write the following

statement import Java do

util this is a package do scanner

scanner is a class so make sure you have

this import at the top before we get

started to sum up programming we

typically accept input process it then

produce output so that's why accepting

user input is important we would like to

do something with the input so to accept

user input we're going to create a

scanner object so type this scanner

that's the name of the class

class scanner that's going to be the

name of the object we'll be working with

do pay attention to the

capitalization our scanner object is all

lowercase characters whereas in the

first scanner has an uppercase

s scanner scanner equals new scanner add

a set of parenthesis then a semicolon

within the set of parentheses we're

going to type

system.in our scanner object can read

user input however it is good practice

if you create a scanner object at the

end of your program when you're done

we're going to take our scanner object

and use the close

method so scanner. close parenthesis

semicolon if you don't close your

scanner it can lead to unexpected

behavior for example let's say that we

read a file well after we're done

reading the file we'll want to close the

file when we open something we typically

want to close

it we're going to create a prompt within

our console that says enter your name

then a user will be able to type in

their name we'll need a user prompt to

work with so let's say system.out.print

name after receiving this prompt a user

is going to be able to type in their

name we're going to use our scanner

object scanner

next line parentheses semicolon so a

user is going to be able to type in a

string of text so let's type in our full

name then hit

enter however with this user input we're

not doing anything with it so let's

assign it to a

variable so with our line of scanner.

next line we will declare a variable and

assign it string name equals scanner.

nextline we have declaration and

assignment those two

steps and then once we have our name

let's output it system.out.print line

name so enter your name type in your

full name hit enter and the output

should be hello whatever your first and

last name is now if you prefer we can

put the input on the same line as the

prompt we're going to use print instead

of print Line Print line will add a new

line character to the

end so let's stick with

print so the input will be on the same

line as the prompt if you prefer it that

way so the next line method of our

scanner object it reads A String of

characters including any spaces if you

so if I were to type in my full name

with the first and last name separated

with the

space we only get the first name next

doesn't read any

spaces so use what you would prefer I

typically just use next

line to read an integer there's a

different method called Next int this

time let's create a prompt of enter your

age I'll use print instead of print line

we will assign a variable of age int age

equals use our scanner

object use the built-in next int

method then once we have our integer of

age let's output it system.out.print

line u

enter your name type in your name enter

your age oops I'm going to add a colon

and a space after my prompt just because

better okay enter your full

name enter your age hello your name you

are whatever your age is years old so

that's how to accept an integer if you

were to type in a floating point number

or a double anything that includes a

decimal now check this out our variable

of age should be an integer if we type

in something that contains a decimal

like a floating Point number or a double

let's say that I'm

25.9 well we get an error here it says

we have an error at line 12 where we

accept an integer so if you need a

double there's a next Double method of

scanners so this time let's ask for a

GPA what is your GPA your grade point

average we will assign a variable that's

going to be of the double data type

double GPA equals again use our

scanner use the next Double

method and then let's output

it system.out.print

line your GPA is plus our variable

GPA so again let's go through the

prompts type in your name type in your

age what is your GPA uh let's use print

Line enter your name enter your age what

is your GPA let's say my GPA is 2.1 I'm

just barely passing hey C get degrees

right your GPA is the GPA variable so

that's how to accept the double use the

next Double method of scanners now for

some reason if you need a Boolean

booleans are either true or false here's

how we can accept

that system.out.print line let's ask are

you a

student then I'll add a prompt for

true or false so the US user knows to

type in one of these instead of yes or

no so we will create a Boolean variable

of is student equals use our scanner

object use the next Boolean

method and then let's output

it system.out.print

line let's say student colon space plus

is student I think an if statement would

be better we'll cover that in a

moment again go through the prompts type

in your name type in your age type in a

GPA are you a student true or false

let's say that's true student

true and again I'm going to use print

instead of print

line not necessary but I think it looks

better let's use an if statement instead

when checking is student is true or not

so if is student again if statements

will be a future lesson we'll cover

pretty soon if is student if that's true

then we will

print let's print you are

enrolled as a

student else we will print something

else if that's not true if it's false you

are

okay enter your name enter your age

enter a GPA are you a student let's say

that it's

false okay we have our name our age our

GPA and then we're outputting you are

not enrolled you are not enrolled in

classes because we said

well then we get the output you are

enrolled as a student that's how to

accept user input of different data

types A few of which include strings

integers doubles and

booleans now there's one common issue

when accepting an integer or double than

demonstrate so we have our scanner

let's say we ask for a user's

age enter your

age and I'll make this a print statement

instead of print

line int age equals use our scanner use

the next int

method and then let's ask what the

user's favorite color is enter your favorite

favorite

color we will store that within a

variable named color and it's going to

be of the string data type string color

equals use our scanner object use the in

next line

method then we'll output the

following system.out.print line you are Plus

Plus

Age years

old as well

as you like the

color plus our variable color

happens enter your age 25 hit

enter enter your favorite color you are

25 years old you like the color so

what's going on here exactly so when we

type in a number for example 25 then hit

enter within the input buffer there's

still a new line character because we

hit enter

so the next line method is picking up

that new line character and using that

as the

input so we need to get rid of that new

line character this is a common problem

that you might see in Java if you accept

an integer or a double then accept a

string of text so one way in which we

can clear the input buffer to get rid of

that new line character is after

accepting an integer or a double we can

use our scanner and call the next line

method but don't assign it to anything

that should get rid of that new line

character in the input buffer if that

problem comes up so let's try this again

enter an age enter a color you are 25

years old you like the color red so if

you encounter that problem I would just

call the next line method of your

scanner object to clear the input buffer

now we're going to cover an

exercise in this exercise we're going to

calculate the area of a rectangle

what I like to do when creating a

project is declare all of my variables

at the top again make sure that you're

importing the scanner class I will

create a double variable of width I'll

set that to be

zero and a double variable of height also

also

zero and double

area I will set that to be

zero we're going to accept some user input

input

and reassign width and

height so we need a scanner object to

accept user input scanner scanner equals

new scanner parentheses semicolon within

the parenthesis we will type

system.in and again since we're opening

a scanner it's good practice to close it

I sometimes forget to do that scanner.

close we'll create a prompt to tell the

user to enter in a width we can use

system.out.print line or print for

prompts I like to use

print enter the

width we will take our width we've

already declared our width once we don't

need to type the data type again we can

reuse it width equals use our scanner

object use the an next Double method

because we're accepting a double a width

let's do this with height I'll just copy

height all right let's test it

currently let's make up some numbers 3.1 and

and

4.2 all right once we have the width and

the height we have to calculate the area

so we're going to take our area variable equals

equals

height and then let's output

it system.out.print line the area

is plus our variable

area so let's say 3.2 and

after area We'll add centimeters you

could do centimet squared if you prefer

or you could even add a superscript of

two so if you're on Windows make sure

num lock is on hold alt then type 0178

on the

numpad if you would like a superscript

of two you know because we're working with

with

areas so let's say

5.3 and

we're going to create a game of Mad Libs

Mad Libs is a game where you have a

story and a user fills in different

words the result is that it gives you a

story that's really silly or doesn't

necessarily make sense at times but

that's what we'll be doing in this video

it will help us practice accepting user

input since we're accepting user input

we'll need to import the scanner class

at the top of our Java file import java.util.scanner

java.util.scanner

a scanner is going to help us accept

user input we'll declare that and assign

it scanner scanner equals new scanner parenthesis

parenthesis

semicolon then within the parenthesis we

system.in when writing a program I like

to declare all of my variables first all

these variables are going to be of the

string data type we will need an

adjective you're going to get an English

lesson today

too adjective one an adjective describes

something like Fast slow cheap

expensive we'll need a noun string noun

one a noun is a person place or thing

we'll need another

adjective adjective

two we'll need a verb a verb is an

action like sleeping or running verb one

then another adjective a again an

adjective describe something all right

so let's work on our

lines so for the first line we'll say

today I went to

a we'll insert an adjective adjective

one we're going to describe a zoo that

we went to

we haven't asked for user input yet

we're getting a warning that this

variable has not been initialized that's

okay we'll take care of that

soon so today I went to a a description

an adjective

exhibit I saw

a plus a noun a noun is a person place

or thing like a gorilla or

harambe then we'll add some punctuation a

and our verb verb one then add some punctuation

so we could say that harambe was big and

action I

was plus adjective

three then add some

punctuation all right now we just need

to accept user input so let's do that

after assigning the variables we'll need

statements we will prompt the user to

enter an

adjective enter an adjective I'll give a

hint that an adjective is a

something enter a

noun I'll give a hint that we are

looking for

person we'll need another adjective we

can just copy this

line then we need a

verb enter a verb and we want it in

present tense so ending with ing like

running I'll give a hint that a verb is an

action and then another

adjective all right now we just need to

assign these variables we've already declared

declared

them adjective one equals take our

method and really we can just copy this

line paste it and then change what we're

assigning it to

we're accepting strings for each of

these lines we have adjective one noun

one adjective

2 verb one and adjective

3 all right now the last thing that I'm

forgetting since we opened up a scanner

it is good practice to close it at the

end of our file if we don't it can lead

to unexpected Behavior if we leave any open

open

resources scanner. close all right we

are ready to run this

I'm going to prefix a new line character

before displaying our

story just so that it's not so close to

the prompts when outputting

it enter an adjective a

suspicious enter a noun so I like making

fun of Mark Zuckerberg I'm going to

write the name of a person Mark

Zuckerberg enter an adjective

smelly enter a verb ending with ing

ing

screaming enter an adjective

happy and here's our Mad Libs game today

I went to a suspicious zoo in an exhibit

I saw a Mark

Zuckerberg Mark Zuckerberg was smelly

and screaming I was happy so for your

Mad Libs game post your results in the

comment section because I would like to

read them I want to see what you you

guys wrote or if you wrote a different

story post that too and well everybody

that is a simple Mad Libs game that we

Java all right everybody so we got a

really important topic to discuss today

although I can be a little dry and that

is the use of different arithmetic

operators in Java when it comes to

programming you got to math sometimes

it's a pretty important topic so let's

start with some basic addition in this

demonstration we will have three

variables X will equal 10 y will equal 2

and Z will store the result we'll

declare it but not yet assign it so for

basic addition we'll store our result

within z z equals X for addition you can

use the plus sign

Y what is 10 + 2 then we'll display

it we're storing the result within

Z which gives us 12

then we have

subtraction z = x -

y 10 - 2 is 8

multiplication for multiplication we're

going to use an asterisk 10 *

2 is

20 for division we use a forward slash z

= x / y 10 /

2 is

5 there's also the modulus operator

which is a percent sign that would give

you the remainder of any

division Z is going to store the

remainder this time x modulus y so

modulus is a percent sign 10 divides by

two evenly so the remainder is going to be

zero but if we divided 10 by three that

doesn't divide evenly

10 modulus 3 gives us a remainder of one

the modulus operator is really useful if

you need to determine if a number is

even or not or when working with time

you need to see if something is

divisible by 60 seconds or 60

minutes we'll get more into that later

but you should at least know what the

modulus operator

is now we have something called

augmented assignment operators instead

of storing the result within Z this time

we're going to reassign the result to

variable X so let's say we would like to

add 10 and 3 together but store it

within X well we could say x = x + y

this would technically

work so 10 + 3 is 13 but there is a

shortcut though that we could use and

that is by using augmented assignment

operators we'll condense some of these

steps instead of saying x = x + y we

simply say x + = y and that does the same

same

thing 10 + 3 is

13 there's also

subtraction x = X -

y 10 - 3 is 7 but we could condense it

to be x - equal

y that gives us

7 or multiplication x = x * y 10 * 3 is

30 but we can condense it to be x * =

y that is also

30 for division x = x /

y that gives us three now one thing to

pay attention to with division all right

so 10 / 3 should be 3.33 repeating right

well we're using something called

integer division we're not able to store

the decimal portion because we're

working with whole integers so that's

something to pay attention to when

you're using integer Division if we were

working with

doubles then we would retain that

decimal portion so do pay attention to

that we'll discuss that in another video

when it comes to typ casting for the

augmented assignment version that would

be x / = Y and let's change that to be 2

so 10 / 2 is

5 then we have the modulus operator x =

x modulus y 10 divides by 2

evenly X will be zero the augmented

assignment version of this would be X

modulus equals

y and that would also be 0o but if y were

were

three then that would be one now we have

increment and decrement operators you

see this a lot with looping structures

let's say that x equal 1 this time

instead of saying x = x + 1 which would

give us 2 or even the augmented

assignment inversion which would be X+ =

1 well there's even a shortcut for this

if we're only incrementing by one and

that is

x++ we're incrementing X by

one you tend to see this in a lot of

looping structures but that's a topic

for another day each time I increment X by

1 it's going to be retained so now x = 3

x ++ again well now X is

4 now there's also the decrement

operator x = X - one of course that's

going to be zero this

time so to decrement you can use x - minus so now X is zero let's do it again

minus so now X is zero let's do it again X

X -- now X is -1 x

-- now X is -1 x -- X is

-- X is -2 so those are the increment and

-2 so those are the increment and decrement operators you'll see these

decrement operators you'll see these again when we reach the topic on Loops

again when we reach the topic on Loops the last thing I need to discuss today

the last thing I need to discuss today is the order of operations and there's

is the order of operations and there's an acronym PEMDAS it's parentheses

an acronym PEMDAS it's parentheses exponents multiplication division

exponents multiplication division addition then subtraction in that order

addition then subtraction in that order you may hear the phrase to remember this

you may hear the phrase to remember this please excuse my dear Aunt Sally but I

please excuse my dear Aunt Sally but I like the phrase please excuse my dope

like the phrase please excuse my dope ass swag that's my version that I like

ass swag that's my version that I like to use let's say we have the equation

to use let's say we have the equation double result equals 3 + 4 time

double result equals 3 + 4 time parentheses 7 - 5 divided by

parentheses 7 - 5 divided by 2.0 I'm dividing by 2.0 because right

2.0 I'm dividing by 2.0 because right now we're using integer division which

now we're using integer division which we previously talked about so I'm going

we previously talked about so I'm going to use 2.0 so we retain that decimal

to use 2.0 so we retain that decimal portion again that's a topic for another

portion again that's a topic for another day let's display the

day let's display the result so I don't know what the result

result so I don't know what the result is but it is 7

is but it is 7 7.0 in what order do we solve this

7.0 in what order do we solve this equation exactly well we can use that

equation exactly well we can use that acronym of pendos

acronym of pendos from the left to the right we solve

from the left to the right we solve anything within parentheses first so

anything within parentheses first so going from the left to the right we skip

going from the left to the right we skip over any addition multiplication we're

over any addition multiplication we're looking for parentheses which we have

looking for parentheses which we have right here if you enclose part of an

right here if you enclose part of an equation within parentheses you would

equation within parentheses you would solve that first 7 - 5 is 2 there's no

solve that first 7 - 5 is 2 there's no more

more parentheses then we check any exponents

parentheses then we check any exponents there are no

there are no exponents

exponents multiplication well we have

multiplication well we have multiplication right here we would solve

multiplication right here we would solve that next 4 * 2 is 8 there's no more

that next 4 * 2 is 8 there's no more multiplication then we have

multiplication then we have division we have 8 / 2 which gives us

division we have 8 / 2 which gives us 4 then any addition 3 + 4 is 7 and that

4 then any addition 3 + 4 is 7 and that was our original result and then you

was our original result and then you would do any subtraction last so that is

would do any subtraction last so that is the order of operations when it comes to

the order of operations when it comes to arithmetic operators all right everybody

arithmetic operators all right everybody so that is some basic arithmetic and

so that is some basic arithmetic and different operators you can use in

different operators you can use in Java hey everybody so in this video

Java hey everybody so in this video we're going to create a shopping cart

we're going to create a shopping cart program a user is going to be able to

program a user is going to be able to type in an item set a price for each and

type in an item set a price for each and then ask for a quantity the output is

then ask for a quantity the output is that it's going to give you a total

that it's going to give you a total based on the price and how much you're

based on the price and how much you're buying this would be a good exercise for

buying this would be a good exercise for us to get us more comfortable with

us to get us more comfortable with accepting user input all right let's get

accepting user input all right let's get started everybody we'll need the help of

started everybody we'll need the help of a scanner the scanner allows us to

a scanner the scanner allows us to accept user input we'll need to import

accept user input we'll need to import that at the at the top so be sure that

that at the at the top so be sure that you have this line of code import

you have this line of code import java.util.scanner

java.util.scanner we'll create a scanner object scanner

we'll create a scanner object scanner scanner equals new scanner parentheses

scanner equals new scanner parentheses semicolon type

semicolon type system.in then if we open a scanner it's

system.in then if we open a scanner it's good practice to close it when we're

good practice to close it when we're done with it scanner. close if you leave

done with it scanner. close if you leave resources open it can lead to unexpected

resources open it can lead to unexpected behavior when creating a project I like

behavior when creating a project I like to declare all of my variables at the

to declare all of my variables at the top let's say we have an item name that

top let's say we have an item name that data type is going to be a string string

data type is going to be a string string item what are we buying

item what are we buying exactly we need a price that would be a

exactly we need a price that would be a double because there might be dollars

double because there might be dollars and cents a quantity how many of

and cents a quantity how many of something are we buying int quantity

something are we buying int quantity pick a unit of currency this could be a

pick a unit of currency this could be a character char

character char currency I'm going to initialize this

currency I'm going to initialize this right away American

right away American dollars and then a total we're going to

dollars and then a total we're going to multiply the price by the quantity to

multiply the price by the quantity to give a

give a total double total now if you would like

total double total now if you would like you can initialize some of these right

you can initialize some of these right away and assign them for example let's

away and assign them for example let's say we are at a pizza

say we are at a pizza restaurant I could set the item to be

restaurant I could set the item to be pizza right

pizza right away or within this program we could

away or within this program we could fill it in then let's create some

fill it in then let's create some prompts I'll use

system.out.print what item would you like to

like to buy then let's accept user input we're

buy then let's accept user input we're going to assign our string of item equal

going to assign our string of item equal to use our scanner object and use the in

to use our scanner object and use the in next line

next line method then let's just print it to

method then let's just print it to verify that it's working

what item would you like to buy maybe this time I am buying a hamburger that

this time I am buying a hamburger that will output hamburger we know that we

will output hamburger we know that we can get user input so let's delete this

can get user input so let's delete this line I was just testing it let's ask for

line I was just testing it let's ask for a

a price you could set an initial

price you could set an initial price if you would

price if you would like or we could ask for one depending

like or we could ask for one depending on how you want to write this

on how you want to write this program so let's system. about the

print what is the price for each if we're working with a price a

each if we're working with a price a double we'll use the next Double method

double we'll use the next Double method we're going to assign our price equal to

we're going to assign our price equal to use our scanner. next

use our scanner. next Double and then let's test it by

Double and then let's test it by outputting the

price okay let's say I'm buying a pizza this time what is the price for each

this time what is the price for each $4.99 and that outputs

$4.99 and that outputs $4.99 so it is a good idea every once in

$4.99 so it is a good idea every once in a while to test your code just to be

a while to test your code just to be sure that it all works as you go

sure that it all works as you go along then we'll need a

like we will assign our quantity variable

variable equals

equals scanner. next int since we're working

scanner. next int since we're working with whole numbers this

with whole numbers this time then let's test our quantity to see

time then let's test our quantity to see if it

if it works I don't know maybe I'm buying a

works I don't know maybe I'm buying a hot dog this time what is the price per

hot dog this time what is the price per each

each $4.99 how many would you like I would

$4.99 how many would you like I would like 12 hot dogs

like 12 hot dogs 12 and I'm just going to make sure I'm

12 and I'm just going to make sure I'm using print instead of print line just

using print instead of print line just because I think it looks better

now we'll create a total we don't need user input for that we're going to use

user input for that we're going to use the variables that we've already had

the variables that we've already had after assigning them total equals the

after assigning them total equals the price times the

total maybe I'm buying a pizza or pizzas each is $4.99

pizzas each is $4.99 and I buying three of

and I buying three of them

following I'm going to use a new line character just to separate our output

character just to separate our output from the

from the prompts you have

quantity plus a space character plus our variable

variable item but it might be more than one so

item but it might be more than one so let's say/ s it might be pizza or

let's say/ s it might be pizza or pizzas then we will display the price

pizzas then we will display the price including the unit of

currency your total is I'll add our unit of currency it's a

is I'll add our unit of currency it's a character I picked American dollars but

character I picked American dollars but pick whatever you would like plus our

pick whatever you would like plus our total

total that we have

that we have calculated all right let's see the

calculated all right let's see the result what item would you like to buy I

result what item would you like to buy I would like to buy a pizza what is the

would like to buy a pizza what is the price for each

price for each $4.99 how many would you like I would

$4.99 how many would you like I would like eight pizzas maybe it's for a party

like eight pizzas maybe it's for a party you have bought eight pizzas your total

you have bought eight pizzas your total is

$19.92 all right everybody so that is a shopping cart program that you can write

shopping cart program that you can write as an exercise using

Java hello everybody today we're going to discuss if statements in Java an if

to discuss if statements in Java an if statement performs a block of code if

statement performs a block of code if its condition is true we've discussed

its condition is true we've discussed how Boolean variables can be used within

how Boolean variables can be used within if statements we may be a little

if statements we may be a little familiar with them already in this

familiar with them already in this demonstration we will have a variable of

demonstration we will have a variable of age set it equal to be some

age set it equal to be some age age will be an integer I would like

age age will be an integer I would like to check if my variable of age is

to check if my variable of age is greater than or equal to 18 if so we can

greater than or equal to 18 if so we can print a message that you are an adult to

print a message that you are an adult to write an if statement will type if

write an if statement will type if parentheses curly braces within the set

parentheses curly braces within the set of curly braces we can check a condition

of curly braces we can check a condition to see if it's true so let's check to

to see if it's true so let's check to see if age is greater than or equal to

18 if that's true we'll print the following you are an

adult that would result in US outputting you are an

you are an adult now if this condition was false if

adult now if this condition was false if it's not true let's say that my age is

it's not true let's say that my age is 12 well then we skip over the if

12 well then we skip over the if statement we check if this condition is

statement we check if this condition is true if it is we perform this code if

true if it is we perform this code if not we skip it alternatively we could

not we skip it alternatively we could add an else clause

add an else clause this would be another statement we would

this would be another statement we would add else if this is false then do

add else if this is false then do something else so let's output the

something else so let's output the following you are a

following you are a child since the age is 12 we would

child since the age is 12 we would output you are a

child there's also an else if Clause so we have one of two

we have one of two possibilities do this or do that now we

possibilities do this or do that now we could add something called else if

could add something called else if Clause let's check else

Clause let's check else if age is less than

if age is less than zero if this statement is

zero if this statement is true then let's say you haven't been

true then let's say you haven't been born

born yet now we're doing one of three

yet now we're doing one of three things but it all depends on these

things but it all depends on these conditions our else Clause is kind of

conditions our else Clause is kind of like the default if none of the above

like the default if none of the above conditions are

conditions are true so let's test this my age variable

true so let's test this my age variable is set to

is set to 19 this would display you are an

19 this would display you are an adult if my age variable was -1 we would

adult if my age variable was -1 we would display you haven't been born

display you haven't been born yet this statement was false so we go

yet this statement was false so we go down to the next

down to the next one this is true NE 1 is less than zero

one this is true NE 1 is less than zero so we do

so we do this or if I was 10

this or if I was 10 well then these top two conditions are

well then these top two conditions are both false so we do whatever is within

both false so we do whatever is within the lse

the lse statement you can add as many else if

statement you can add as many else if Clauses as you would

Clauses as you would like so here's another

one else if our variable age is equal to zero

if our variable age is equal to zero exactly double equals is the comparison

exactly double equals is the comparison operator we're checking if a variable or

operator we're checking if a variable or a value is equal to another value or

a value is equal to another value or variable you don't want to use single

variable you don't want to use single equals because that's the assignment

equals because that's the assignment operator Java thinks we're trying to

operator Java thinks we're trying to assign a variable when making a

assign a variable when making a comparison you use double

comparison you use double equals is our variable age equal to

equals is our variable age equal to zero then we'll print something else

zero then we'll print something else okay we're going to print you are a

okay we're going to print you are a baby I will set variable H to be zero

baby I will set variable H to be zero you are a baby because our variable age

you are a baby because our variable age is equal to zero

is equal to zero exactly let's add another L

exactly let's add another L statement there's something I want to

statement there's something I want to demonstrate let's check to

demonstrate let's check to see if age is greater than or equal to

see if age is greater than or equal to 65 then we will print you are a

65 then we will print you are a senior I'll set age to be 70

senior I'll set age to be 70 here's the

here's the result you are an adult so why did we

result you are an adult so why did we print this statement rather than this

print this statement rather than this one well with these if statements we

one well with these if statements we check them from the top down this

check them from the top down this condition is technically true as well as

condition is technically true as well as this one 70 is greater than or equal to

this one 70 is greater than or equal to 18 so we execute this code and skip over

18 so we execute this code and skip over the rest even though this one is also

the rest even though this one is also true you do have to pay attention to the

true you do have to pay attention to the positioning of your if and else if

positioning of your if and else if statements in this situation it would be

statements in this situation it would be better if we were to check to see if

better if we were to check to see if somebody's age was greater than or equal

somebody's age was greater than or equal to 65 first so let's turn this into the

to 65 first so let's turn this into the if

statement and then where we check if age is greater than or equal to 18 we will

is greater than or equal to 18 we will use an else if Clause instead now this

use an else if Clause instead now this should

work you are a senior but if the age was 50

well then you are an adult now we're going to modify this program

going to modify this program slightly this time we will ask for user

slightly this time we will ask for user input we'll need the help of a scanner

input we'll need the help of a scanner at the top of our Java file we're going

at the top of our Java file we're going to import

to import java.util dothe class of

java.util dothe class of scanner we'll need to create a scanner

scanner we'll need to create a scanner object scanner scanner equals new

object scanner scanner equals new scanner within the set of parentheses

scanner within the set of parentheses type system.in

type system.in then when we open a scanner it is a good

then when we open a scanner it is a good idea to close it when we're done with

idea to close it when we're done with it just so we don't leave any resources

it just so we don't leave any resources open with our variable of age we're

open with our variable of age we're going to create a prompt to have a user

going to create a prompt to have a user enter in their age I'm going to declare

enter in their age I'm going to declare a variable of age but we'll assign it

a variable of age but we'll assign it later let's create a

later let's create a prompt enter your

prompt enter your age I'll use print instead of print

age I'll use print instead of print line and then we will assign age equal

line and then we will assign age equal to scanner. next

to scanner. next int okay let's try this

int okay let's try this again and to your age let's say that I'm

again and to your age let's say that I'm 21 you are an

adult what if I was 99 you are a senior I am negative 1 years old you

senior I am negative 1 years old you haven't been born

haven't been born yet I am zero exactly you are a

yet I am zero exactly you are a baby or maybe I'm 10 you are a

baby or maybe I'm 10 you are a child so with if statements we check a

child so with if statements we check a condition if it's true we do it we do

condition if it's true we do it we do this code if not we don't otherwise we

this code if not we don't otherwise we can check another condition with else if

can check another condition with else if and if none of these conditions are true

and if none of these conditions are true we can perform whatever is within an

we can perform whatever is within an else statement else acts like the

else statement else acts like the default code if none of the above

default code if none of the above conditions are true now this time we're

conditions are true now this time we're going to work with strings

going to work with strings we're going to create a variable of name

we're going to create a variable of name and it's going to be a string we'll

and it's going to be a string we'll declare it but not yet assign

declare it but not yet assign it we will prompt the user to enter in

it we will prompt the user to enter in their name I will use print instead of

their name I will use print instead of print

print Line enter your

Line enter your name we will assign our variable of name

name we will assign our variable of name equal to scanner. next line to get a

equal to scanner. next line to get a line of text

this group of if else if and else statements let's set this to be group

statements let's set this to be group two we're going to create another

set this will be group one for the name when somebody enters in their name

name when somebody enters in their name they could skip the prompt like this

they could skip the prompt like this enter your name I'm just going to hit

enter your name I'm just going to hit enter to skip

enter to skip it we will check if our name variable is

it we will check if our name variable is empty here's how

empty here's how if we'll check if our name is empty

if we'll check if our name is empty there's a string method for this we

there's a string method for this we haven't discussed string Methods yet

haven't discussed string Methods yet instead of saying name is equal to an

instead of saying name is equal to an empty space there is a built-in method

empty space there is a built-in method of strings and that is to take our

of strings and that is to take our variable name dot is

variable name dot is empty this is another way to check to

empty this is another way to check to see if a string is empty this will be

see if a string is empty this will be our condition is empty will give you a

our condition is empty will give you a Boolean of true or false

Boolean of true or false so let's print the following if our name

so let's print the following if our name variable is

variable is empty let's say you didn't enter your

empty let's say you didn't enter your name else if our name is not empty that

name else if our name is not empty that means somebody typed in their name let's

means somebody typed in their name let's say hello plus name and I'll add an

say hello plus name and I'll add an exclamation

exclamation point okay let's try this

point okay let's try this again enter your name if I hit enter

again enter your name if I hit enter we'll perform then whatever is within

we'll perform then whatever is within the if statement then enter an age you

the if statement then enter an age you didn't enter your name you are an adult

didn't enter your name you are an adult this time let's type in our name our

this time let's type in our name our first

name hello whatever your name is you are an

an adult this time we have two groups of if

adult this time we have two groups of if else statements group one is for the

else statements group one is for the name group two is for the user's age

name group two is for the user's age this time let's create a

this time let's create a Boolean Boolean is

student then we'll create a prompt let's ask are you a student but

prompt let's ask are you a student but we need a value of true or

we need a value of true or false cuz booleans can only be true or

false cuz booleans can only be true or false

false normally is student equals use our

normally is student equals use our scanner to get some user input next

Boolean now we'll create another group of if and lse if

of if and lse if statements group

statements group three we need an if

statement so with booleans we could say is student is equal to true but there is

is student is equal to true but there is a way to simplify this a

a way to simplify this a shortcut you can just say is student it

shortcut you can just say is student it holds a direct value of true or false we

holds a direct value of true or false we don't necessarily need to write like a

don't necessarily need to write like a whole condition

whole condition so if we're a student we'll

so if we're a student we'll output you are a

output you are a student else if a student is

student else if a student is false then we'll output you are not a

false then we'll output you are not a student we have three groups of if else

student we have three groups of if else statements group three is for is

statements group three is for is student group two is for the

student group two is for the age group one is for the

age group one is for the name just to make this more fun I'm

name just to make this more fun I'm going to add some emojis I think it

going to add some emojis I think it would make it more interesting but you

would make it more interesting but you don't have to so if somebody doesn't

don't have to so if somebody doesn't enter their name I'm going to add a

enter their name I'm going to add a pouting

pouting face if somebody enters their name I

face if somebody enters their name I will add a smiley

will add a smiley face if somebody is a senior maybe we

face if somebody is a senior maybe we can find an emoji for a

adult you haven't been born yet uh we could do like a spirit or

something you are a baby you are a

school you are not a student we could do an

an office all right so this is our final

office all right so this is our final program

again we have three groups of if statements this time one for the name

statements this time one for the name one for the age and one for is student

one for the age and one for is student and then for the prompt for are you a

and then for the prompt for are you a student I'm going to use print instead

student I'm going to use print instead of print

line here's the result enter your name enter your age are you a

student hello your name you are an adult you are not a student

you are not a student let's try some of the other statements

let's try some of the other statements I'm not going to enter a name for the

I'm not going to enter a name for the age let's say that I'm

age let's say that I'm ne1 are you a student

ne1 are you a student true you didn't enter your name you

true you didn't enter your name you haven't been born yet you are a

haven't been born yet you are a student so those are if statements

student so those are if statements everybody they perform a block of code

everybody they perform a block of code if its condition is true check a

if its condition is true check a condition if it's true do this if not

condition if it's true do this if not you can do something else and well

you can do something else and well everybody that summar mizes if

everybody that summar mizes if statements in

statements in Java hey everybody in this video I'm

Java hey everybody in this video I'm going to show you how we can work with

going to show you how we can work with the random class and generate some

the random class and generate some random numbers let's begin to work with

random numbers let's begin to work with random numbers we'll need to import the

random numbers we'll need to import the random class at the top of our Java file

random class at the top of our Java file we will import java. u.

we will import java. u. random much like what we do with the

random much like what we do with the scanner class we're going to follow a

scanner class we're going to follow a similar pattern for creating a random

similar pattern for creating a random object much like a scanner object we

object much like a scanner object we will type the name of the class random

will type the name of the class random the name of the random object random

the name of the random object random equals new

equals new random so random random equals new

random so random random equals new random let's say we have an integer an

random let's say we have an integer an integer variable of number I'm going to

integer variable of number I'm going to assign our number variable equal to and

assign our number variable equal to and here's where we'll generate a random

here's where we'll generate a random number we will take our random object

number we will take our random object then we will use the next int method

then we will use the next int method this will generate a random number

this will generate a random number however there's one issue with this I'm

however there's one issue with this I'm going to print our

going to print our number the number is going to be very

number the number is going to be very large so the random number that's

large so the random number that's generated it's going to be within a

generated it's going to be within a range between just about -2 billion and

range between just about -2 billion and positive2 billion I'm guessing you don't

positive2 billion I'm guessing you don't want a number that big So within the

want a number that big So within the next integer method we can set some

next integer method we can set some bounds if I would like a random number

bounds if I would like a random number between 1 and six like I'm rolling a

between 1 and six like I'm rolling a dice or die I would say 1 comma 6 this

dice or die I would say 1 comma 6 this is actually going to give us a random

is actually going to give us a random number between 1 and

five the first number is inclusive the second number is exclusive no matter how

second number is exclusive no matter how many times I rerolled this die I'm never

many times I rerolled this die I'm never going to get

six since this number is exclusive I'm going to inrease this to be seven that

going to inrease this to be seven that will give us 1 through

six and there's six let's say this time you would like three random numbers

you would like three random numbers you're rolling three dice let's say we

you're rolling three dice let's say we have number one number two and number

have number one number two and number three all

three all integers we'll assign number one with a

integers we'll assign number one with a random integer and we'll do this with

random integer and we'll do this with numbers two and three as well number one

numbers two and three as well number one number two number number

number two number number three then we will print them number one

three then we will print them number one number two number

three 2 46 23 4

46 23 4 225 good enough for random numbers

225 good enough for random numbers between 1 and 100 the second number is

between 1 and 100 the second number is going to be 101 because it's

going to be 101 because it's exclusive so now we're generating three

exclusive so now we're generating three random numbers between 1 and 100

not only can you generate random numbers you can Generate random

number let's change the data type and number to be

double we're going to use the next Double method

this is going to generate a random number between zero and

number between zero and one just the decimal portion

really you can also generate a Boolean this might be good in a situation where

this might be good in a situation where you need to flip a coin let's say we

you need to flip a coin let's say we have a Boolean of is

have a Boolean of is heads when we flip a coin is it heads

random. nextext Boolean then we will display if the coin

Boolean then we will display if the coin we flip is heads or not is it heads or

we flip is heads or not is it heads or it's Tails that's true it is

it's Tails that's true it is heads now it's false it's

heads now it's false it's Tails we could even use an if

Tails we could even use an if statement if is heads if our coin flip

statement if is heads if our coin flip is on

is on heads let's

heads let's print heads

print heads else we will

else we will print

Tails so this will simulate us flipping a

Tails all right everybody that is how you can Generate random numbers and use

you can Generate random numbers and use the random module in Java

hey everybody in this video we're going to cover some useful math related

to cover some useful math related constants and methods that you may be

constants and methods that you may be interested in as a beginner then at the

interested in as a beginner then at the end of this topic we'll cover a few

end of this topic we'll cover a few exercises let's begin if at any time you

exercises let's begin if at any time you need the value of pi there's a built-in

need the value of pi there's a built-in constant of the math class so I'm going

constant of the math class so I'm going to print the

to print the following math with a capital M Pi all

following math with a capital M Pi all capital so that would give you the value

capital so that would give you the value 3.14 and some change so instead of

3.14 and some change so instead of creating a variable for pi it's always

creating a variable for pi it's always available to you within the math class

available to you within the math class you just have to access it there's also

E this is the exponential constant also known as ul's number you may never use

known as ul's number you may never use this but it's available to you in case

this but it's available to you in case you do so again access the math class

you do so again access the math class Dot to name the

Dot to name the constant this time let's create a double

constant this time let's create a double variable named result here's a few

variable named result here's a few methods I'm going to reassign result

methods I'm going to reassign result equal to access math dot to raise a base

equal to access math dot to raise a base to a given power you can use the pal

to a given power you can use the pal method let's raise 2 to the^ of 3 then

method let's raise 2 to the^ of 3 then print

print it let's print our variable result 2 ^

it let's print our variable result 2 ^ of 3 would be 8

of 3 would be 8 and again I'm using a double that's why

and again I'm using a double that's why we have the decimal portion 2^ of 4

we have the decimal portion 2^ of 4 would

would be 16 2 the^ of

be 16 2 the^ of 5 is

5 is 32 po meaning power you can raise a base

32 po meaning power you can raise a base to a given power these can be values or

to a given power these can be values or variables there's the absolute value

variables there's the absolute value method math.abs for absolute value

method math.abs for absolute value what's the absolute value

of5 that would be five positive 5 basically speaking the absolute value

basically speaking the absolute value method gives you that number but

method gives you that number but positive if it's negative think of it as

positive if it's negative think of it as the distance away from zero if that

the distance away from zero if that helps for square root there's a square

helps for square root there's a square root method result equals

root method result equals math.sqrt

math.sqrt what is the square root of 9 I did make

what is the square root of 9 I did make a spelling mistake here if you're

a spelling mistake here if you're accessing the math class make sure it's

accessing the math class make sure it's with a capital m so the square root of 9

with a capital m so the square root of 9 would be

3 we can also round a number again access the math class use

number again access the math class use the round

method let's round 3.14 round will round a number to the

3.14 round will round a number to the nearest whole

integer again we're working with the double though so that gives us

3.0 to always round up there's the ceiling

ceiling method math. c

method math. c l again I accidentally used lowercase M

l again I accidentally used lowercase M it's capital M let's round 3.14 up to

it's capital M let's round 3.14 up to the

the ceiling so 3.14 rounded up is four to

ceiling so 3.14 rounded up is four to always round down you can use the floor

always round down you can use the floor method

method math.

math. floor so this time let's round 3.99 down

floor so this time let's round 3.99 down normally it should round up

normally it should round up right so 3.99 rounded down is

right so 3.99 rounded down is three you can find the max between two

three you can find the max between two values or variables

values or variables math. Max method we'll have two numbers

math. Max method we'll have two numbers which are comma separated 10 and 20 what

which are comma separated 10 and 20 what is the max between these two values or

is the max between these two values or variables

the greater number is 20 there's also Min I'll just copy this cuz I'm lazy

Min I'll just copy this cuz I'm lazy replace Max with Min what is the minimum

replace Max with Min what is the minimum value between these two

value between these two values that would be

values that would be 10 so those are a few useful math

10 so those are a few useful math methods and constants that you may be

methods and constants that you may be interested in we're going to cover some

interested in we're going to cover some math related exercises if you would like

math related exercises if you would like additional practice

in this first exercise we're going to find the hypotenuse of a right triangle

find the hypotenuse of a right triangle you can follow this formula C the

you can follow this formula C the hypotenuse equals the square root of a^

hypotenuse equals the square root of a^ 2 one of the sides plus b^2 the other

2 one of the sides plus b^2 the other side we're going to accept some user

side we're going to accept some user input we'll need a scanner we need to

input we'll need a scanner we need to import the scanner class import

import the scanner class import java.util do

java.util do scanner then we'll create a scanner

scanner then we'll create a scanner object scan scanner scanner equals new

object scan scanner scanner equals new scanner then place system.in within the

scanner then place system.in within the set of

set of parentheses then when we open a scanner

parentheses then when we open a scanner it is a good idea to close it so we

it is a good idea to close it so we don't leave any resources open scanner.

don't leave any resources open scanner. close we'll prompt the user to enter in

close we'll prompt the user to enter in the length of side A and B let's declare

the length of side A and B let's declare those as variables double a double b

those as variables double a double b we'll also declare Double C that will

we'll also declare Double C that will store the hypotenuse

store the hypotenuse Double

Double C we'll need two

C we'll need two prompts I will use print instead of

prompts I will use print instead of print

print Line enter the length of side

a with inside a within our variable of a we'll assign it to scanner. next

we'll assign it to scanner. next Double let's do this with side B we can

Double let's do this with side B we can copy these two lines paste them replace

copy these two lines paste them replace a with

a with B that is lowercase

B that is lowercase b let's do a test run just to be sure

b let's do a test run just to be sure that these two work

that these two work temporarily I'm going to print a then

B enter the length as side a 3 B will be four these work I just wanted to test

four these work I just wanted to test that it is a good idea to test your code

that it is a good idea to test your code as you're writing it then we have to

as you're writing it then we have to follow this

follow this equation C equals math. square root of

equation C equals math. square root of a^2 +

a^2 + b^2 there is a square root method within

b^2 there is a square root method within the math class but we have to raise side

the math class but we have to raise side a to the power of two plus b to the^ of

a to the power of two plus b to the^ of two here's how we can do that so within

two here's how we can do that so within the square root method we're going to

the square root method we're going to raise a to the power of two first math

raise a to the power of two first math po to raise a base to a given power

po to raise a base to a given power raise a comma to the power of

raise a comma to the power of two plus again math.pow to raise a base

two plus again math.pow to raise a base to a given power B to the power of

to a given power B to the power of two and that's it so let's display

two and that's it so let's display whatever C is the

hypotenuse the

the hypotenuse I'll write that this is C

hypotenuse I'll write that this is C side

C is the following plus

C if side a is three side B is four side C should be five which it is if you

C should be five which it is if you would prefer we can add a unit of

would prefer we can add a unit of measurement such as centimet or inches

measurement such as centimet or inches so after side C add cm for centimet or I

so after side C add cm for centimet or I for inches whatever you

for inches whatever you prefer so let's try that again side a

prefer so let's try that again side a will be four side B will be

will be four side B will be five and side C is this really long

five and side C is this really long number we haven't talked about the print

number we haven't talked about the print F statement yet using print F you can

F statement yet using print F you can display a given amount of digits but we

display a given amount of digits but we do have centimeters at the end which is

do have centimeters at the end which is what we were looking for so let's try

what we were looking for so let's try three and four and that gives us 5

three and four and that gives us 5 cm all right let's cover another

exercise given the radius of a circle or a sphere we'll return the circumference

a sphere we'll return the circumference the area then the volume that's if we're

the area then the volume that's if we're working with the sphere given the radius

working with the sphere given the radius so be sure that we're importing our

so be sure that we're importing our scanner at the top and we'll create a

scanner at the top and we'll create a scanner object scanner scanner equals

scanner object scanner scanner equals new

new scanner system.in then be sure to close

scanner system.in then be sure to close your

your scanner scanner .

scanner scanner . close we'll prompt the user for a

close we'll prompt the user for a radius because we need a radius to work

radius because we need a radius to work with we'll create a variable it will be

with we'll create a variable it will be a double named radius we'll declare it

a double named radius we'll declare it but not yet assign

but not yet assign it we'll prompt the user using print

it we'll prompt the user using print instead of print

instead of print Line enter the

Line enter the radius then we will assign our radius

radius then we will assign our radius variable radius

variable radius equals scanner.

equals scanner. next

next Double once we have a radius we have to

Double once we have a radius we have to follow these formulas so we need a

follow these formulas so we need a circumference area and volume let's

circumference area and volume let's declare those at the top of our program

declare those at the top of our program but assign them later double

but assign them later double circumference I think I spelled that

right double area double

area double volume we will calculate the

volume we will calculate the circumference

here's the Formula 2 times we need pi to work with

Formula 2 times we need pi to work with instead of typing

instead of typing 3.14159 so on and so forth we can access

3.14159 so on and so forth we can access that from the math class

that from the math class math.pi Pi is always available to

math.pi Pi is always available to us then multiply this by the

us then multiply this by the radius let's perform a test

radius let's perform a test run I will display the circumference

run I will display the circumference the

the circumference

circumference is plus our variable of

is plus our variable of circumference then I'll add a unit of

circumference then I'll add a unit of measurement afterwards centimeters is

measurement afterwards centimeters is good or whatever you

prefer enter the radius I'll enter in five the circumference is 31.4 CM in the

five the circumference is 31.4 CM in the future using print F we can limit the

future using print F we can limit the amount of digits that are displayed I'll

amount of digits that are displayed I'll show you how to do that later on in this

show you how to do that later on in this video then we need the

video then we need the area area

area area equals here's the formula again we need

equals here's the formula again we need Pi Pi is always available to us math. pi

Pi Pi is always available to us math. pi times our radius to the^ of two so we

times our radius to the^ of two so we need the power method of math

need the power method of math math.pow raise the radius to the power

math.pow raise the radius to the power of

of two and I'll just copy this line because

two and I'll just copy this line because I'm

I'm lazy the area is our variable area now

lazy the area is our variable area now when working with an area the unit of

when working with an area the unit of measurement is going to be squared so we

measurement is going to be squared so we can raise it to the power of two or you

can raise it to the power of two or you can use superscript to if you're on

can use superscript to if you're on Windows make sure numlock is on hold alt

Windows make sure numlock is on hold alt then on the numpad type

then on the numpad type 0178 for a superscript of two if you

0178 for a superscript of two if you would like to use that

would like to use that instead so now what is the

instead so now what is the area enter the radius 5

area enter the radius 5 the area is 78.53982

doubles times math. pi and again make sure the m is

3 math. power method raise our radius to the power of

three then display the volume the volume is our variable volume cm

is our variable volume cm cubed for a superscript of three make

cubed for a superscript of three make sure numb lock is on hold alt then type

sure numb lock is on hold alt then type 0179 that's if you're on

0179 that's if you're on Windows all right let's print the

Windows all right let's print the volume again my radius is

volume again my radius is five then we have the

five then we have the circumference the area and the

circumference the area and the volume and the unit of measurement is

volume and the unit of measurement is cenm cubed now we haven't talked about

cenm cubed now we haven't talked about the print F statement we could display

the print F statement we could display just a few digits here's

just a few digits here's how again this is a future topic replace

how again this is a future topic replace print line with print

F instead of adding plus our variable name we're going to add a

name we're going to add a placeholder

placeholder percent F to display a double but if you

percent F to display a double but if you would like one digit between the percent

would like one digit between the percent and F type .1 so let's do this with area

and F type .1 so let's do this with area and

and volume replace the plus with a

comma then instead of adding plus centim after our

after our placeholder add

placeholder add CM then cm

CM then cm squar and cm

squar and cm cubed then we can get rid of the portion

cubed then we can get rid of the portion where we add the centimeters to the end

so let's say the radius is five then we should add a new line character to the

should add a new line character to the end of each of

these that looks much better we're only displaying one digit

better we're only displaying one digit after the decimal again don't worry

after the decimal again don't worry about this this is a future topic the

about this this is a future topic the print F statement but if you would only

print F statement but if you would only like to display one digit that's how you

like to display one digit that's how you can do that again we'll cover this later

can do that again we'll cover this later all right everybody so those are a few

all right everybody so those are a few math related constants and methods that

math related constants and methods that you may be interested in as a

beginner what's up everybody in this video I'm going to discuss the print F

video I'm going to discuss the print F statement in Java print f is a method

statement in Java print f is a method used to format output we already do have

used to format output we already do have a little bit of experience using print F

a little bit of experience using print F in the last few topics involving math

in the last few topics involving math we'll get more in depth with the print F

we'll get more in depth with the print F stat in this topic print f is an

stat in this topic print f is an alternative to print and print line

alternative to print and print line wherever we would like to insert a

wherever we would like to insert a variable we can add a placeholder of a

variable we can add a placeholder of a percent sign then add one of a few

percent sign then add one of a few characters following it to format the

characters following it to format the output in this demonstration let's

output in this demonstration let's create a few variables let's create a

create a few variables let's create a string of name I'll assign some name

string of name I'll assign some name I'll pick SpongeBob because many people

I'll pick SpongeBob because many people know who SpongeBob is we'll need a

know who SpongeBob is we'll need a character let's say character first

character let's say character first letter equals

letter equals s int age equals

s int age equals 30 and a double double

30 and a double double height equals

height equals 60.5 and a Boolean Boolean is

60.5 and a Boolean Boolean is employed I will set that to be true

employed I will set that to be true SpongeBob is employed at the K crusty

SpongeBob is employed at the K crusty Krab so we have some variables they're

Krab so we have some variables they're all different data types we can insert

all different data types we can insert them into print F statements when we

them into print F statements when we output string literal here's a

demonstration instead of using print line I'm going to use print

line I'm going to use print F we will display the

F we will display the following

following hello then I would like to insert this

hello then I would like to insert this variable of name we're going to use a

variable of name we're going to use a percent sign as a

percent sign as a placeholder percent then we need a

placeholder percent then we need a specifier our character what is the data

specifier our character what is the data type of the variable we're trying to

type of the variable we're trying to insert if you're trying to insert a

insert if you're trying to insert a string you're going to use a lowercase

string you're going to use a lowercase s so after this word of hello we're

s so after this word of hello we're adding a placeholder then inserting a

adding a placeholder then inserting a string at this location so instead of

string at this location so instead of adding plus the variable

adding plus the variable name we're going to comma separate any

name we're going to comma separate any variables we're inserting so comma name

variables we're inserting so comma name here's the

output hello our variable name which contains

contains SpongeBob if we need to insert a

SpongeBob if we need to insert a character that would be lower case C so

character that would be lower case C so let's use

let's use system.out.print

system.out.print F I don't know let's say your name

F I don't know let's say your name starts with a we're going to insert a

starts with a we're going to insert a variable we need a placeholder that

variable we need a placeholder that perent sign lower case C for a Char

perent sign lower case C for a Char variable then comma separate any

variable then comma separate any variables comma our variable of first

letter so here's an important thing too with a print F statement we have to

with a print F statement we have to manually insert any new line characters

manually insert any new line characters we'll end each print F statement with a

we'll end each print F statement with a new line

new line character so after our format specifier

character so after our format specifier We'll add back sln to insert a new

line that's better otherwise the output is going to be all on the same

is going to be all on the same line so that's how to insert a character

line so that's how to insert a character percent C for

percent C for chars then for an integer we use

chars then for an integer we use D so print

f u r we're going to insert a variable we use D for

we use D for integers you are our variable age years

integers you are our variable age years old than a new line character then we

old than a new line character then we will insert our variable

age you are 30 years old and in the middle is our variable of

and in the middle is our variable of age for a double that would be

f system.out.print

f you are add a placeholder f for floating Point number think of that as a

floating Point number think of that as a double inches tall or you can pick

double inches tall or you can pick centimeters up to you

centimeters up to you then we will insert our variable of

height you are 60.5 then a bunch of zeros inches tall

60.5 then a bunch of zeros inches tall we can limit the amount of digits that

we can limit the amount of digits that are displayed after the decimal we'll

are displayed after the decimal we'll have to set a Precision but I'll explain

have to set a Precision but I'll explain that

that later then a Boolean all we need is the

later then a Boolean all we need is the letter

letter b

b system.out.print

system.out.print f let's say

f let's say employed add a

employed add a placeholder B then a new line

placeholder B then a new line character we will display our variable

character we will display our variable of is

employed employed then our variable of true now you can insert multiple

true now you can insert multiple variables within the same line here's

variables within the same line here's how we'll use

how we'll use system.out.print

system.out.print f we're going to inst insert our

f we're going to inst insert our variable of name

variable of name SpongeBob for a string the specifier

SpongeBob for a string the specifier character is going to be lowercase s for

character is going to be lowercase s for a string so string SpongeBob

a string so string SpongeBob is we're inserting an integer we need

is we're inserting an integer we need percent

percent D years old we'll comma separate all

D years old we'll comma separate all variables we're inserting we have a

variables we're inserting we have a string followed by an integer so that

string followed by an integer so that would be name comma age we're inserting

would be name comma age we're inserting two variables of this time SpongeBob is

two variables of this time SpongeBob is 30 years

30 years old so those are specifier characters

old so those are specifier characters add a percent sign a placeholder then

add a percent sign a placeholder then follow this placeholder with a specifier

follow this placeholder with a specifier character depending on what the data

character depending on what the data type is s for Strings C for

type is s for Strings C for chars D for integers f for doubles or

chars D for integers f for doubles or other floating Point numbers and B for

other floating Point numbers and B for booleans it might take a little bit of

booleans it might take a little bit of time to remember

time to remember these now we'll cover Precision with

these now we'll cover Precision with setting the Precision we can limit the

setting the Precision we can limit the amount of digits that display after a

amount of digits that display after a decimal let's create three different

decimal let's create three different prices and these will be of the double

prices and these will be of the double data type price 1 equals

$9.99 price two I'm just making up numbers here

10.15 and double price 3 equals 5

equals 5 $41 we're going to use print F to

$41 we're going to use print F to display these

display these prices

prices system.out.print F we're going to insert

system.out.print F we're going to insert we'll use that percent placeholder then

we'll use that percent placeholder then use f to display a double f for floating

use f to display a double f for floating Point

Point number comma our variable of price one

number comma our variable of price one then we'll do this with price two and

then we'll do this with price two and price

price three price one price two price three

three price one price two price three and here are the prices oh and we have

and here are the prices oh and we have to add a new line character too because

to add a new line character too because they're all in the same line I forgot to

they're all in the same line I forgot to do that so back sln back

do that so back sln back sln back

sln back sln that's better naturally when we're

sln that's better naturally when we're using print F to display a floating

using print F to display a floating Point number such as a double normally

Point number such as a double normally it displays six digits after the decimal

it displays six digits after the decimal point but we would like to limit that

point but we would like to limit that here's how we're going to set the

here's how we're going to set the Precision

Precision to display one digit after the decimal

to display one digit after the decimal between the percent sign and the F Type

between the percent sign and the F Type .1 to display one

digit so we have 10.0 this will automatically round the

10.0 this will automatically round the output so we have 10.0 100.2 and

output so we have 10.0 100.2 and 54.0 for two digits that would be 02

999 10.15 and

10.15 and 54.1 or we could do

54.1 or we could do three

3F then we have three digits after the decimal so that is precision it's useful

decimal so that is precision it's useful for displaying prices then we have Flags

for displaying prices then we have Flags next let's set the Precision to be 0.2

here's different flags that we can add by adding a plus after the percent sign

by adding a plus after the percent sign we can output a plus for any positive

numbers positive 999 positive 10.15 54.1 is still

54.1 is still negative to display a plus before any

negative to display a plus before any positive numbers just add a plus sign

positive numbers just add a plus sign let's increase these

let's increase these prices let's add three zeros to the end

prices let's add three zeros to the end of

each if you add the flag of a comma it's a comma grouping separator for any

a comma grouping separator for any thousand's place after the percent sign

thousand's place after the percent sign add a

add a comma at any thousand's place we have a

comma at any thousand's place we have a comma grouping separator again this is

comma grouping separator again this is useful for displaying prices

by adding a single left parentheses any negative numbers are enclosed in a set

negative numbers are enclosed in a set of parentheses so let's revert these

of parentheses so let's revert these prices

prices back after the percent sign add a left

parentheses so we only have one negative price-

54.1 and then we have a space character this will display a minus if negative

this will display a minus if negative space space if positive we have two

space space if positive we have two positive numbers in one negative one so

positive numbers in one negative one so by using a space

character any positive numbers are preceded with a space 54.1 is negative

preceded with a space 54.1 is negative so we do not have that space it's good

so we do not have that space it's good for aligning

for aligning numbers the last specifier we have to

numbers the last specifier we have to talk about is

talk about is width we're going to create some ID

width we're going to create some ID numbers these will be integers int id1 =

numbers these will be integers int id1 = 1 int id2 =

1 int id2 = 23 in

23 in ID3 equal

7890 these integers have a varying number of digits 1 2 3 4 by setting the

number of digits 1 2 3 4 by setting the width we can align them here's how again

width we can align them here's how again we're going to use print F we're

we're going to use print F we're displaying an integer so we need percent

displaying an integer so we need percent D we will Begin by displaying

D we will Begin by displaying id1 then let's do this with 2 three and

id1 then let's do this with 2 three and four as

four as well 2 3

4 and again I am missing that new line character new line new line

character new line new line new

new line new

line new line that's better so we have our four

line that's better so we have our four IDs by adding a zero after the percent

IDs by adding a zero after the percent sign we can zero pad some of these

values but Java is giving us a warning by how many characters do we want to pad

by how many characters do we want to pad these numbers with

these numbers with zero let's say four we have one variable

zero let's say four we have one variable that has four digits we'll set it to be

that has four digits we'll set it to be four to be the maximum so

04 and here we are these ID numbers are all now zero

all now zero padded and they align vertically which

padded and they align vertically which is kind of

is kind of nice so to add some zero padding follow

nice so to add some zero padding follow our placeholder with zero then the

our placeholder with zero then the amount of digits to Zer pad in this case

amount of digits to Zer pad in this case four by setting a positive number we can

four by setting a positive number we can WR justify these variables

WR justify these variables so let's replace zero with just

so let's replace zero with just four rather than having that zero

four rather than having that zero padding we just have some spaces if you

padding we just have some spaces if you would prefer it that

would prefer it that way or with a negative number we can

way or with a negative number we can left justify these

left justify these values so let's set four to be instead

values so let's set four to be instead -4 now these values are left Justified

-4 now these values are left Justified and we still have those spaces

and we still have those spaces afterwards except for the last variable

afterwards except for the last variable because it's already four digits

because it's already four digits all right everybody so that is the print

all right everybody so that is the print F statement it's a method used to format

F statement it's a method used to format output you add a placeholder then one of

output you add a placeholder then one of a few characters afterwards there is

a few characters afterwards there is Flags width precision and specifier

Flags width precision and specifier characters depending on the data type of

characters depending on the data type of what you want to display we'll have more

what you want to display we'll have more practice with this in the future and

practice with this in the future and well everybody that is print F in

Java hey everybody this video serves as a project we're going to create a

a project we're going to create a compound interest calculator using Java

compound interest calculator using Java if you put money in a bank account or

if you put money in a bank account or the stock market using the given formula

the stock market using the given formula we can determine what our final amount

we can determine what our final amount is going to be plus interest after a

is going to be plus interest after a given amount of time this project serves

given amount of time this project serves as an exercise using Java let's begin

as an exercise using Java let's begin all right let's get started everybody

all right let's get started everybody the first thing we'll need is a scanner

the first thing we'll need is a scanner we'll need to import it at the top of

we'll need to import it at the top of our Java file import input

our Java file import input import

import java.util.scanner

we need to create a scanner object again scanner scanner equals new

scanner scanner equals new scanner then within the set of

scanner then within the set of parentheses type

parentheses type system.in when you open a scanner it is

system.in when you open a scanner it is good practice to close the scanner when

good practice to close the scanner when you're done with it so you don't leave

you're done with it so you don't leave any resources

any resources open after creating our scanner here the

open after creating our scanner here the different variables we'll need double

different variables we'll need double principal this will store the principal

principal this will store the principal amount what's our original investment an

amount what's our original investment an interest rate double rate

interest rate double rate an integer for times compounded how

an integer for times compounded how often does our interest compound like

often does our interest compound like yearly quarterly

yearly quarterly monthly then we need an amount of time

monthly then we need an amount of time such as years into

years and the final amount double

double amount now we have to get some user

amount now we have to get some user input we'll need some prompts first we

input we'll need some prompts first we need the principal amount all use

system.out.print enter the principal I never spell principal right enter the

never spell principal right enter the principal

amount we are working with the double so we need the next Double method of our

we need the next Double method of our scanner principal equals our

scanner principal equals our scanner do next

Double then we need the interest rate this is going to be a

this is going to be a double

system.out.print enter the interest rate I'll add within our prompt that

rate I'll add within our prompt that this is in a percentage form like 5% or

this is in a percentage form like 5% or so the number five instead of

so the number five instead of 05 so then we have our interest

05 so then we have our interest rate so we need our scanner do next

rate so we need our scanner do next double so let's say somebody types in

double so let's say somebody types in five for

five for 5% we would like the rate to be 05

5% we would like the rate to be 05 rather than 5 after accepting the user

rather than 5 after accepting the user input let's divide that number by 100 or

input let's divide that number by 100 or let's say somebody types in seven we

let's say somebody types in seven we don't want the rate to be seven we want

don't want the rate to be seven we want it to be

it to be 07 that's why we're dividing by

07 that's why we're dividing by 100 we'll fill in the times compounded

100 we'll fill in the times compounded variable we're going to use print

enter the number of times

times compounded per

compounded per year so this could be yearly that would

year so this could be yearly that would be one quarterly four or monthly would

be one quarterly four or monthly would be 12 in most cases it's probably going

be 12 in most cases it's probably going to be one for yearly times

to be one for yearly times compounded equals use our

scanner next int cuz we're accepting an

next int cuz we're accepting an integer then we need the amount of times

integer then we need the amount of times our money is going to be

invested enter the number of years then we need to assign our

years then we need to assign our variable years years equals

variable years years equals scanner. next int because we're working

scanner. next int because we're working with an integer then we need to

with an integer then we need to calculate the total amount here's the

calculate the total amount here's the formula

amount equals we need our principal

amount times access the math class use the power

the power method raay is 1 plus the interest

rate divided by the variable times compounded so this is going to be the

compounded so this is going to be the base we Comm separate the base and the

base we Comm separate the base and the power we are raising this part of our

power we are raising this part of our equation to the

equation to the power of times

power of times compounded times the number of

compounded times the number of years and that's our

years and that's our formula it's a little confusing but it

formula it's a little confusing but it should

should work then we will display the

work then we will display the amount system.out.print

amount system.out.print line the amount

after plus years plus

plus is pick a unit of currency I'll pick

is pick a unit of currency I'll pick American

dollars plus amount let's test

amount let's test this so let's say we have $10,000 or so

this so let's say we have $10,000 or so and we're putting it in the

and we're putting it in the bank what is the interest rate

bank what is the interest rate maybe

maybe 3% so I'm going to type three enter the

3% so I'm going to type three enter the amount of times compounded per year I'll

amount of times compounded per year I'll go with

go with one enter the number of years

one enter the number of years one so we should have 10,300 in our

one so we should have 10,300 in our bank which we do

bank which we do 10,300 if you would like you can use a

10,300 if you would like you can use a print F statement to format the

print F statement to format the output so if you're familiar with that

output so if you're familiar with that let's replace print line with print

let's replace print line with print F instead of concatenating these

F instead of concatenating these variables we'll add some placeholders

instead so to display an integer we need percent D within print

percent D within print F

F years is then to display a double we

years is then to display a double we need percent F then we'll list our

need percent F then we'll list our arguments

arguments years comma

amount so to display two decimals within a double between the percent and the F

a double between the percent and the F we're going to type 2 to display two

we're going to type 2 to display two digits after the

digits after the decimal we'll proceed this placeholder

decimal we'll proceed this placeholder with the unit of currency let's do

with the unit of currency let's do American dollars okay let's see the

American dollars okay let's see the total

total amount enter the principal amount

amount enter the principal amount $110,000 enter the interest rate 2%

$110,000 enter the interest rate 2% enter the number of times compounded per

enter the number of times compounded per year this time let's do quarterly so

year this time let's do quarterly so four because there's four quarters in a

four because there's four quarters in a year enter the number of years let's do

year enter the number of years let's do two

two actually and here's the amount in our

actually and here's the amount in our bank account after 2 years

$1,477 all right everybody so that is a compound interest calculator you can

compound interest calculator you can write using

Java what is going on everybody in this video I'm going to explain nested if

video I'm going to explain nested if statements in Java

statements in Java in Java it is possible to have if

in Java it is possible to have if statements within other if statements

statements within other if statements kind of like

kind of like this after checking some condition you

this after checking some condition you could follow with another condition if

could follow with another condition if the first condition is true you can add

the first condition is true you can add if

if statements L if

statements L if statements and or else

statements and or else statements really depends on the program

statements really depends on the program that you're trying to write so what

that you're trying to write so what we're going to do in this demonstration

we're going to do in this demonstration is have two Boolean

is have two Boolean variables a Boolean of is

variables a Boolean of is student let's say that we're selling

student let's say that we're selling movie tickets if somebody's a student

movie tickets if somebody's a student they get a 10% discount on their movie

they get a 10% discount on their movie ticket we also have a senior discount

ticket we also have a senior discount Boolean is

Boolean is senior if somebody is 65 or older they

senior if somebody is 65 or older they get a 20% senior

get a 20% senior discount or if they're a student and a

discount or if they're a student and a senior they get a combined total of 30%

senior they get a combined total of 30% off their ticket

off their ticket price let's say we have a double of

price let's say we have a double of price the price of a movie ticket will

price the price of a movie ticket will be $9.99 let's say that's actually kind

be $9.99 let's say that's actually kind of cheap

of cheap nowadays we'll write an if statement to

nowadays we'll write an if statement to check to see if somebody is a student if

check to see if somebody is a student if is student is equal to true but since

is student is equal to true but since this is a Boolean variable we don't need

this is a Boolean variable we don't need the equals true portion we can just say

the equals true portion we can just say if is student I will go ahead and set

if is student I will go ahead and set this to be true right away so if

this to be true right away so if somebody is a student they get a student

somebody is a student they get a student discount else they

won't so if a student is true let's output the

output the following you get a

following you get a student discount of

student discount of 10% then we will take our

10% then we will take our price price equals price time

price price equals price time 0.9 that will give you a 10% discount

0.9 that will give you a 10% discount account you could shorten this using the

account you could shorten this using the augmented assignment operator price

augmented assignment operator price times equals

times equals 0.9 that will set the price to be

0.9 that will set the price to be 90% or a 10% discount so to say if

90% or a 10% discount so to say if somebody's not a student they're going

somebody's not a student they're going to pay full price price times equals 1

to pay full price price times equals 1 that really doesn't do anything but it

that really doesn't do anything but it might help with this

might help with this visualization then we'll output the

is pick unit of currency then I'll add our price let's perform a test

our price let's perform a test run currently we're a student you get a

run currently we're a student you get a discount of 10% the price of a ticket is

$8.99 to limit the amount of digits that display let's use a printf statement

display let's use a printf statement we'll use print F instead of print line

we'll use print F instead of print line after the dollar sign I will add a

after the dollar sign I will add a format specifier we're going to display

format specifier we're going to display a double we'll use f for a floating

a double we'll use f for a floating Point

Point number comma price to display two digits

number comma price to display two digits after the decimal use 0

after the decimal use 0 2 now we can display a

2 now we can display a price you get a student discount of 10%

price you get a student discount of 10% the price of a ticket is

the price of a ticket is $8.99 now if we weren't a student I'll

$8.99 now if we weren't a student I'll set this to be

false we don't get that discount the price of a ticket is $9.99 what it was

price of a ticket is $9.99 what it was originally now what if somebody is a

originally now what if somebody is a senior and a student within our if

senior and a student within our if statement we'll write a nested if

statement we'll write a nested if statement as well as an else

statement as well as an else statement if is senior they get a

statement if is senior they get a student discount and a senior

student discount and a senior discount let's cut these two lines

discount let's cut these two lines within the if statement and stick them

within the if statement and stick them within the nested else statement

within the nested else statement if somebody is a senior and a

if somebody is a senior and a student you get a senior

20% and a student discount of 10% so let's take our original

10% so let's take our original price times equals

so let's say is senior is true for now okay else if they're not a student

now okay else if they're not a student but they are a

senior we'll check that with a nested if statement within the else

statement within the else statement if is senior they get that

statement if is senior they get that senior

senior discount but it's only 20% instead of 30

discount but it's only 20% instead of 30 because they're not also as

student price times equals 0.8 you could add

0.8 you could add else price times equals

else price times equals 1 that's if somebody is not a student

1 that's if somebody is not a student and not a senior but you don't

and not a senior but you don't necessarily need the sell

necessarily need the sell statement all right let's perform a test

run let's say that we're not a student and not a senior

the price of a ticket is $9.99 what if we were a student but not

$9.99 what if we were a student but not a

a senior you get a student discount of 10%

senior you get a student discount of 10% the price of a ticket is

the price of a ticket is $8.99 what if we're not a student but we

$8.99 what if we're not a student but we are a

senior you get a senior discount of 20% the price of a ticket is

the price of a ticket is $7.99 what if we're both a student and a

senior you get a senior discount of 20% you get a student discount of 10% the

you get a student discount of 10% the price of a ticket is

price of a ticket is $6.99 that's how nesa if statements can

$6.99 that's how nesa if statements can be useful you could check another

be useful you could check another condition after checking a condition

condition after checking a condition already so that's just one example of

already so that's just one example of nesa if statements and well everybody

nesa if statements and well everybody those are Nesta if statements in

Java hey yeah so today I'm going to show you a few useful string Methods you may

you a few useful string Methods you may be interested in as a beginner using

be interested in as a beginner using Java in this demonstration let's create

Java in this demonstration let's create a variable of name the data type is

a variable of name the data type is going to be a string type in your full

going to be a string type in your full name including a

name including a space I'll just use my YouTube channel

space I'll just use my YouTube channel name if at any time you need the length

name if at any time you need the length of a string you can use the length

of a string you can use the length method I'll store that as an integer int

method I'll store that as an integer int length equals to access these string

length equals to access these string Methods you need a string or a variable

Methods you need a string or a variable that is a string

that is a string dot then we have one of a few methods if

dot then we have one of a few methods if you need the length you can use the

you need the length you can use the length

length method and then let's print

it print the length how many characters are in the string

are in the string eight 1 2 3 4 5 6 7 8 this could be

eight 1 2 3 4 5 6 7 8 this could be useful let's say somebody is setting a

useful let's say somebody is setting a password and you have a maximum size of

password and you have a maximum size of 12 characters well you can check the

12 characters well you can check the length to see if it's under 12

length to see if it's under 12 characters so that is the length

characters so that is the length method there's Char at that will give

method there's Char at that will give you the character at a specified index

you the character at a specified index we'll be given a single character we'll

we'll be given a single character we'll store that as a variable Char letter

store that as a variable Char letter equals take our string of name use the

equals take our string of name use the Char at

Char at method within the Char at method we'll

method within the Char at method we'll list an index zero is the index of the

list an index zero is the index of the first character because computers like

first character because computers like to start at zero what what is the

to start at zero what what is the character at index

character at index zero well that letter is B at index

zero well that letter is B at index one that would be R and

one that would be R and two would be

two would be o that is the charat method it returns a

o that is the charat method it returns a character at a given index within a

character at a given index within a string we also have the capability of

string we also have the capability of finding a letter at a given

finding a letter at a given index let's say we have a variable of

index let's say we have a variable of index take our name use the index of

index take our name use the index of method find the first occurrence of an

method find the first occurrence of an O so in my example that should be 2 0 1

O so in my example that should be 2 0 1 2 that is the first index of this

2 that is the first index of this character o what about a

character o what about a space well that would be three 0 1 2

3 there's also last index last index equals take our string

index last index equals take our string of

of name then use the last index of

name then use the last index of method what is the last index of an O

method what is the last index of an O because index of gives you the first

because index of gives you the first index last gives you well the last

index last gives you well the last one what is the last index of O where is

one what is the last index of O where is it exactly

it exactly five 0 1 2 3 4 5

five 0 1 2 3 4 5 we can take a string and make all the

we can take a string and make all the characters uppercase all reassign that

characters uppercase all reassign that to our name variable so we're going to

to our name variable so we're going to take our name use the two uppercase

take our name use the two uppercase method then print our name after

method then print our name after reassigning

reassigning it now all the letters are

it now all the letters are uppercase there's also two

uppercase there's also two lowercase we'll replace upper with

lowercase we'll replace upper with lower and I should probably turn this

lower and I should probably turn this into a comment

into a comment now all the characters are

lowercase we can trim any white space before and after a string let's add a

before and after a string let's add a few spaces before and after then print

few spaces before and after then print the

the name we can eliminate all this white

name we can eliminate all this white space we'll use the trim method for that

space we'll use the trim method for that we'll reassign name equals name and use

we'll reassign name equals name and use the trim

method now while that white space is gone we can replace a character with

gone we can replace a character with another

another one name equals name we will replace one

one name equals name we will replace one character with another let's replace any

character with another let's replace any o's with A's for your own name feel free

o's with A's for your own name feel free to change

these so what is my name now

now broade there are methods that return

broade there are methods that return Boolean values to check to see if a

Boolean values to check to see if a string is empty you can use the is empty

string is empty you can use the is empty method this would return a Boolean to

method this would return a Boolean to demonstrate I'm going to put this within

demonstrate I'm going to put this within a print

statement so my string is not empty that's false but if it was it would

that's false but if it was it would return true but I have to turn these

return true but I have to turn these lines into

comments that would return true my name is empty this could be useful within an

is empty this could be useful within an if statement

if name do is empty method if our name is empty we will

method if our name is empty we will print your name is

print your name is empty else we will

print hello plus

hello plus name currently my name is

name currently my name is empty your name is

empty your name is empty this method returns true but if it

empty this method returns true but if it wasn't

wasn't it would return

it would return false hello whatever your name

is I'll use a multi-line comment just to comment all this

out we can check to see if our string contains a character that would return a

Boolean let's check to see if our name contains any spaces

true your name contains a

contains a space else will print your

space else will print your name doesn't

name doesn't contain any

contain any spaces so my name does contain a

spaces so my name does contain a space that would return true your name

space that would return true your name contains a

contains a space if we're working with let's say a

space if we're working with let's say a username usernames typically don't

username usernames typically don't contain

contain spaces your name doesn't contain any

spaces your name doesn't contain any spaces there is a method to check to see

spaces there is a method to check to see if two strings are

if two strings are equal again I'm going to use a

equal again I'm going to use a multi-line comment just to comment this

out if our name equals

name equals using the equals method we can check to

using the equals method we can check to see if two strings are equal the given

see if two strings are equal the given characters within them let's see if our

characters within them let's see if our name equals

password this actually would be more appropriate if we were working with the

appropriate if we were working with the string named password if our name if the

string named password if our name if the string of name is equal to this string

string of name is equal to this string if they have the same characters exactly

if they have the same characters exactly then we'll print your name can't be

then we'll print your name can't be password

else we will print

print hello plus

hello plus name I will set my name to be

password your name can't be password but if it

wasn't well then this returns false these two strings are not equal and we

these two strings are not equal and we execute the L statement hello your name

execute the L statement hello your name now the equals method doesn't account

now the equals method doesn't account for case sensitivity so let's say our

for case sensitivity so let's say our password has a capital

P well then this method returns false hello password to ignore case

hello password to ignore case sensitivity you can use equals ignore

sensitivity you can use equals ignore case then that would return true your

case then that would return true your name can't be password all right

name can't be password all right everybody those are a few useful string

everybody those are a few useful string Methods you may be interested in as a

Methods you may be interested in as a beginner using

beginner using Java all right everybody in this video

Java all right everybody in this video I'm going to explain how the substring

I'm going to explain how the substring method Works in Java substring is a

method Works in Java substring is a method that's used to extract a portion

method that's used to extract a portion of a string strings have a built-in

of a string strings have a built-in method of substring within the substring

method of substring within the substring method you can list one of two indices

method you can list one of two indices this method will create a new string

this method will create a new string based on the positioning of the indices

based on the positioning of the indices the start and the end I can best

the start and the end I can best demonstrate this with us creating an

demonstrate this with us creating an email SCE ER program so what we'll do in

email SCE ER program so what we'll do in this demonstration is create a string of

this demonstration is create a string of email type in your own email I don't

email type in your own email I don't want to give you guys my actual email

want to give you guys my actual email because some of you guys are weird no

because some of you guys are weird no offense my email will be bro1

offense my email will be bro1 23@gmail.com

our variable of email is a string strings have a built-in method of

strings have a built-in method of substring we can create a new string

substring we can create a new string from portions of the original string

from portions of the original string here's

here's how let's say I would like the first six

how let's say I would like the first six letters but depending on your own email

letters but depending on your own email it may be different the substring method

it may be different the substring method will return a new string so let's create

will return a new string so let's create a new variable the data type of string

a new variable the data type of string of usern

of usern name equals to create a substring we

name equals to create a substring we will take the original string use the

will take the original string use the substring

substring method then list one of two possible

method then list one of two possible indexes or indices the first index will

indexes or indices the first index will be zero at what position would we like

be zero at what position would we like this substring to end I would like to

this substring to end I would like to end right before this at sign so that

end right before this at sign so that would be 0 1 2 3 4 5

would be 0 1 2 3 4 5 6 the second index is exclusive so we're

6 the second index is exclusive so we're creating a new string of username by

creating a new string of username by using the substring method of our

using the substring method of our original string of email then let's

original string of email then let's print it to test it we will display our

print it to test it we will display our username and now we have a new string

username and now we have a new string mine is bro 1 123 but depending on what

mine is bro 1 123 but depending on what you wrote for your email it may be

you wrote for your email it may be different now I would like a new

different now I would like a new substring of every character after the

substring of every character after the at sign this will be a variable named

at sign this will be a variable named domain what is the domain of our email

domain what is the domain of our email again we're taking our original string

again we're taking our original string using the substring method then list one

using the substring method then list one of two possible indices so again let's

of two possible indices so again let's count this is index zero because in

count this is index zero because in programming we tend to start with zero 1

programming we tend to start with zero 1 2 3 4 5 6

7 so 7 8 9 10 11 12 13 14 15 16 then we will display our

domain so my domain is gmail.com within your substring method

gmail.com within your substring method if you have a starting index but you

if you have a starting index but you would like all the characters that come

would like all the characters that come after all the way till the end you don't

after all the way till the end you don't necessarily need an ending index X we

necessarily need an ending index X we could just say seven that would work too

could just say seven that would work too gmail.com there's one issue with how we

gmail.com there's one issue with how we wrote this program what if somebody has

wrote this program what if somebody has a different length of an email there's a

a different length of an email there's a greater or lesser number of characters

greater or lesser number of characters so let's say I have a different

email this program doesn't work as intended it's not flexible so my domain

intended it's not flexible so my domain is 1@gmail.com

is 1@gmail.com I could could modify the indices of the

I could could modify the indices of the substring method so 0 1 2 3 4 5 6

78 then the domain would be nine because I want everything after the at

sign and then my username let's check that so this would be my username bro

that so this would be my username bro code one to make this program more

code one to make this program more flexible instead of manually entering

flexible instead of manually entering the indices we can determine this number

the indices we can determine this number should be with another string method

should be with another string method we're going to use the index of method

we're going to use the index of method in place of a number we're going to find

in place of a number we're going to find the at character let's replace our

the at character let's replace our second

second index with email our string dot using

index with email our string dot using the index of method then we will find

the index of method then we will find the index of our at character we're

the index of our at character we're going to replace this number with email.

going to replace this number with email. index of and find the at sign so now

index of and find the at sign so now let's try printing our

let's try printing our username so here's my

username so here's my username then let's print the

domain currently we have that at sign the index of method returns a number

the index of method returns a number which we're using as the index it's

which we're using as the index it's returning the index of this at sign I'm

returning the index of this at sign I'm going to increase it by one so we get

going to increase it by one so we get everything after the at sign so plus

everything after the at sign so plus one and now the at sign is removed

one and now the at sign is removed even better yet let's accept some user

even better yet let's accept some user input we'll need a scanner import

input we'll need a scanner import java.util do scanner we'll create a

java.util do scanner we'll create a scanner

scanner object scanner scanner equals new

object scanner scanner equals new scanner then we will need

scanner then we will need system.in then when we open a scanner it

system.in then when we open a scanner it is a good idea to close it when we're

is a good idea to close it when we're done with it I sometimes forget

we'll create a prompt for a user to type in their

in their email enter your email I'll use print

email enter your email I'll use print instead of print line I'm going to

instead of print line I'm going to declare my variables after our scanner

declare my variables after our scanner that's just how I like to arrange things

that's just how I like to arrange things we'll declare our email but not yet

we'll declare our email but not yet assign

assign it same thing applies with our

it same thing applies with our username and our

username and our domain we've already declared these

domain we've already declared these variables we don't need to do that again

instead of manually assigning our email we're going to use our scanner to accept

we're going to use our scanner to accept user input scanner. nextt

user input scanner. nextt line let's display our username and our

domain okay enter your email I'll make up something bro1 123@gmail.com

up something bro1 123@gmail.com here's my username

here's my username and the

and the domain we can take this a step further

domain we can take this a step further too we can check to see if our email is

too we can check to see if our email is valid we'll use some of the string

valid we'll use some of the string Methods we learned about in the last

Methods we learned about in the last video so after accepting our email we're

video so after accepting our email we're going to write an if

going to write an if statement if our email contains the at

character our email is only valid if we have this at character if it is

have this at character if it is then we'll perform all this code so

then we'll perform all this code so let's cut it then stick it within the if

let's cut it then stick it within the if statement else we will do something

statement else we will do something else let's print emails must contain

else let's print emails must contain at let's type in an email that's not

at let's type in an email that's not valid I won't include the at

sign emails must contain the at character let's try that

character let's try that again fake

again fake guy one at maybe they're using Yahoo

guy one at maybe they're using Yahoo yahoo.com so my username would be fake

yahoo.com so my username would be fake guy one the domain is

guy one the domain is yahoo.com all right everybody so that is

yahoo.com all right everybody so that is the substring method and how to create

the substring method and how to create an email slicer program the substring

an email slicer program the substring method is used to extract a portion of a

method is used to extract a portion of a string you can list one of two possible

string you can list one of two possible indices within the substring method a

indices within the substring method a starting index and an ending index we

starting index and an ending index we use the substring method on an email

use the substring method on an email then created two new substrings one of

then created two new substrings one of username and the other of domain and

username and the other of domain and well everybody that is the substring

well everybody that is the substring method in

method in Java hey everybody in this video we're

Java hey everybody in this video we're going to create a weight conversion

going to create a weight conversion program to convert a weight from pounds

program to convert a weight from pounds to kilogram or vice versa it will help

to kilogram or vice versa it will help us become more familiar with if

us become more familiar with if statements so let's get started okay

statements so let's get started okay let's get started everybody what might

let's get started everybody what might be helpful to you as a beginner when

be helpful to you as a beginner when creating a project is to use comments to

creating a project is to use comments to describe what you want to do at each

describe what you want to do at each part of your program this is also known

part of your program this is also known as pseudo code for example the first

as pseudo code for example the first thing we'll do is declare our variables

thing we'll do is declare our variables declare

message then a prompt for user input prompt for user input or

Choice we'll say option one convert lbs meaning pounds to to kgs

one convert lbs meaning pounds to to kgs kilog option two convert kgs to

kilog option two convert kgs to LBS if somebody doesn't select option

LBS if somebody doesn't select option one or two we'll use an else statement

one or two we'll use an else statement else print not a valid

else print not a valid choice so here's a rough outline of our

choice so here's a rough outline of our program and what it's going to do we'll

program and what it's going to do we'll begin at the top we'll declare any

begin at the top we'll declare any variables that we'll need so we will

variables that we'll need so we will need a scanner we'll create a scanner

need a scanner we'll create a scanner object scanner scanner equals new

object scanner scanner equals new scanner then type system.in within set

scanner then type system.in within set of parentheses if you hover over the

of parentheses if you hover over the word scanner you can import it

word scanner you can import it automatically import

automatically import java.util.scanner or otherwise you can

java.util.scanner or otherwise you can type it

type it in what are some other variables we'll

in what are some other variables we'll need double weight for the original

need double weight for the original weight double new

weight double new weight that's after we convert the

weight that's after we convert the weight we'll need to store it and int

weight we'll need to store it and int choice

choice a user is going to type in one to

a user is going to type in one to convert pounds to kilograms or two to

convert pounds to kilograms or two to convert kilograms to

convert kilograms to pounds we have our variables now we need

pounds we have our variables now we need a welcome

a welcome message I'll use a few print

message I'll use a few print statements let's say weight

statements let's say weight conversion

program one C and space this means opt one convert lbs

space this means opt one convert lbs meaning pounds to kgs

meaning pounds to kgs kilog or Choice

kilog or Choice 2 to colon space convert kilogram to

2 to colon space convert kilogram to pounds

pounds lbs then we'll prompt for a user's

Choice I'll use print instead of print line choose an option

then we'll need to store that choice variable Choice equals use our scanner

variable Choice equals use our scanner to accept user input we're accepting an

to accept user input we're accepting an integer we'll use next

integer we'll use next int let's do a test run and I will print

int let's do a test run and I will print our choice

temporarily weight conversion program one to convert pounds to kilograms or

one to convert pounds to kilograms or two to convert kilograms to pounds I'll

two to convert kilograms to pounds I'll type in one we get one

type in one we get one or

or two then we output two we can delete

two then we output two we can delete this print line statement we were just

this print line statement we were just checking to see if it

checking to see if it works okay option one if somebody

works okay option one if somebody selects option one we have to convert

selects option one we have to convert pounds to

pounds to kilograms well we'll need to check to

kilograms well we'll need to check to see if choice is one we can use an if

see if choice is one we can use an if statement for

statement for that if choice is equal to one be sure

that if choice is equal to one be sure you use double equals that is the

you use double equals that is the comparison operator we're checking if

comparison operator we're checking if these two values are equal if you use a

these two values are equal if you use a single equals that is the assignment

single equals that is the assignment operator and Java thinks you're trying

operator and Java thinks you're trying to assign one to choice so double equals

to assign one to choice so double equals for

for comparisons we're converting pounds to

comparisons we're converting pounds to kilograms we'll ask a user to enter the

kilograms we'll ask a user to enter the weight in

weight in lbs I'll use print instead of print

line we we will assign our weight equals use our scanner then use

weight equals use our scanner then use the next Double method then we will

the next Double method then we will accept a double value so once we have

accept a double value so once we have our weight we have to convert it to

our weight we have to convert it to kilograms because it's currently in

kilograms because it's currently in pounds we will assign our new weight

pounds we will assign our new weight equal to the weight our current weight

equal to the weight our current weight that

that is times

is times 0.45 3592

weight the new weight in

new weight in kgs

kgs is then we'll add our new

is then we'll add our new weight okay let's perform a test

weight okay let's perform a test run we'll type in one to convert pounds

run we'll type in one to convert pounds to kilogram enter the weight in pounds

to kilogram enter the weight in pounds what's 150 lb converted to kilog

what's 150 lb converted to kilog 68.0

68.0 388 if you would like to limit the

388 if you would like to limit the amount of digits that display after the

amount of digits that display after the decimal you can use a print F statement

decimal you can use a print F statement instead of print line so to do that

instead of print line so to do that we'll convert this to print

we'll convert this to print F where we would like to insert a value

F where we would like to insert a value or variable we'll use percent since

or variable we'll use percent since we're displaying a double we'll use f

we're displaying a double we'll use f meaning floating Point number to display

meaning floating Point number to display two digits after the decimal we'll use 0

two digits after the decimal we'll use 0 2 or 0.1 to display one digit depending

2 or 0.1 to display one digit depending on your preference replace the plus with

on your preference replace the plus with a

a comma we're inserting this variable at

comma we're inserting this variable at this location this placeholder let's

this location this placeholder let's perform that

perform that again choose an option convert pounds to

again choose an option convert pounds to kilograms enter the weight in pounds 150

kilograms enter the weight in pounds 150 is good the new weight in kilogram is

is good the new weight in kilogram is 68.4

68.4 kilg now if Choice equals 2 we're going

kilg now if Choice equals 2 we're going to convert kilog to pounds and really we

to convert kilog to pounds and really we can just copy the if statement paste it

can just copy the if statement paste it then convert

then convert it else if Choice equals 2 the user

it else if Choice equals 2 the user wants to convert kilogram to pounds

wants to convert kilogram to pounds enter the weight in

enter the weight in kilog the new formula is going to be

kilog the new formula is going to be weight time

weight time 2.24

2.24 62 the new weight in pounds lbs is our

62 the new weight in pounds lbs is our new

new weight let's try

weight let's try it choose an option we will convert

it choose an option we will convert kilograms to pounds I'm going to press

kilograms to pounds I'm going to press two enter the weight in kilogram let's

two enter the weight in kilogram let's say 68

say 68 kg the new weight in pounds is

kg the new weight in pounds is 14991

14991 lb what if somebody types in a number

lb what if somebody types in a number that's not

that's not valid so we can get rid of this comment

valid so we can get rid of this comment is use an else statement to print print

is use an else statement to print print that the user didn't select a valid

that the user didn't select a valid choice we will follow this with an lse

choice we will follow this with an lse statement we will follow else if with an

statement we will follow else if with an else statement else

else statement else print that was not a valid

choice we have options one or two if I type in three we execute the L statement

type in three we execute the L statement that was not a valid

that was not a valid choice and again like usual I'm

choice and again like usual I'm forgetting to close my scanner because I

forgetting to close my scanner because I sometimes forget to do that so at the

sometimes forget to do that so at the end of your program close your scanner

end of your program close your scanner scanner. close because you don't want to

scanner. close because you don't want to leave resources

leave resources open okay let's do one final test run

open okay let's do one final test run let's convert pounds to kilograms what's

let's convert pounds to kilograms what's 200 lb converted to

200 lb converted to kilograms 90.7

kilograms 90.7 2 all right everybody so that is a

2 all right everybody so that is a weight conversion program you can write

weight conversion program you can write using

using [Music]

[Music] Java hey everybody in this video I'm

Java hey everybody in this video I'm going to show you how we can use the

going to show you how we can use the tary operator in Java in Java the tary

tary operator in Java in Java the tary operator is a question mark followed by

operator is a question mark followed by one of two possible values here's the

one of two possible values here's the formula we check a condition then use a

formula we check a condition then use a question mark like we're asking a

question mark like we're asking a question is this condition true if it is

question is this condition true if it is we'll return a value if not we return

we'll return a value if not we return something else a different value it's a

something else a different value it's a simpler version to an if else statement

simpler version to an if else statement here's a

here's a demonstration let's say we have an

demonstration let's say we have an integer of a score score will equal 70

integer of a score score will equal 70 that's technically

that's technically passing using an if statement I will

passing using an if statement I will check if my score is greater than or

check if my score is greater than or equal to

60 if it is then we will print pass else we will

print fail so this does work with a score of 70 I have passed if

work with a score of 70 I have passed if it were 55

it were 55 well then I fail there's another way in

well then I fail there's another way in which we can write this and that is by

which we can write this and that is by using the tary

using the tary operator what we're going to do let's

operator what we're going to do let's create a variable a string variable of

create a variable a string variable of pass or

pass or fail and we're basically just following

fail and we're basically just following this formula we have our condition is

this formula we have our condition is our score greater than or equal to

our score greater than or equal to 60 question mark we're asking a question

60 question mark we're asking a question is this condition true if it is let's

is this condition true if it is let's return a string of pass colon think of

return a string of pass colon think of it like

it like otherwise will return

otherwise will return fail and then I will print pass or fail

fail and then I will print pass or fail to display it so 55 that means we fail

to display it so 55 that means we fail but if it were

but if it were 75 that means we pass by using the tary

75 that means we pass by using the tary operator it's an alternative to writing

operator it's an alternative to writing an if else statement and it can be

an if else statement and it can be simpler in many cases here's a few other

simpler in many cases here's a few other examples let's create a variable of

examples let's create a variable of number set it equal to some

number set it equal to some number using the Turner operator we will

number using the Turner operator we will check if this number is even or

check if this number is even or odd I'll create a string of even or odd

odd I'll create a string of even or odd equals our

equals our condition we can check if a number is

condition we can check if a number is even or odd by using the modulus

even or odd by using the modulus operator

operator we will take our

we will take our number modulus 2 the modulus operator

number modulus 2 the modulus operator gives you the remainder of any division

gives you the remainder of any division does 3 divide by two evenly if it does

does 3 divide by two evenly if it does that would equal

zero 3 doesn't divide by two evenly there's a remainder of one and that does

there's a remainder of one and that does not equal

not equal zero is this number divisible by two

zero is this number divisible by two we'll use the trary operator if it is

we'll use the trary operator if it is we'll return a string of even otherwise

we'll return a string of even otherwise we'll return a string of odd is my

we'll return a string of odd is my number even or

number even or odd so three is

odd so three is odd but if it were

odd but if it were four well then it's

four well then it's even here's a more practical example

even here's a more practical example let's say we're working with a

let's say we're working with a time in hours this will be in military

time in hours this will be in military time hours equals

time hours equals 13 that would be the the same as 1

13 that would be the the same as 1 p.m. I will create a string of time of

p.m. I will create a string of time of day equals we'll check if our hours is

day equals we'll check if our hours is greater than or equal to 12 if it is

greater than or equal to 12 if it is we'll return PM if not will return

we'll return PM if not will return am hours less than

am hours less than 12 tary operator is our hours less than

12 tary operator is our hours less than 12 if it is we'll return a.m.

12 if it is we'll return a.m. otherwise will return

otherwise will return p.m and then we will display the time of

p.m and then we will display the time of day 13 hours that's the same as 1:

day 13 hours that's the same as 1: p.m. yep the time is 1: p.m. or if the

p.m. yep the time is 1: p.m. or if the hours were 9 that would be

hours were 9 that would be am all right last example let's say we

am all right last example let's say we have an income or

have an income or salary income equals $60,000

let's pretend that you're a software engineer in the united states in the

engineer in the united states in the United States we have different tax

United States we have different tax brackets depending on your income this

brackets depending on your income this time we will assign a variable of tax

time we will assign a variable of tax rate equals we'll check if our

rate equals we'll check if our income is greater than or equal

income is greater than or equal to $40,000 for

$40,000 question mark turnar operator if that's true then our tax

operator if that's true then our tax rate is going to be

rate is going to be 0.25 otherwise it will be

0.15 so with our income what is the tax rate

rate 0.25 but if I changed it to

0.25 but if I changed it to 30,000 well then our tax rate would be

30,000 well then our tax rate would be 0.15 for

0.15 for 15% so that is the tary operator you

15% so that is the tary operator you follow this formula you check a

follow this formula you check a condition within a set of parentheses

condition within a set of parentheses then use the tary operator like you're

then use the tary operator like you're asking a question if this condition is

asking a question if this condition is true return this otherwise if it's false

true return this otherwise if it's false return something else and then if you

return something else and then if you would like you can assign it to a

would like you can assign it to a variable and well everybody that is the

variable and well everybody that is the tary operator in

Java all right everybody in this video we're going to create a temperature

we're going to create a temperature conversion program to convert from

conversion program to convert from Celsius to Fahrenheit or Fahrenheit to

Celsius to Fahrenheit or Fahrenheit to Celsius this is a practice project to

Celsius this is a practice project to get us more familiar using the tary

get us more familiar using the tary operator so let's get started we will be

operator so let's get started we will be accepting some user input so let's get

accepting some user input so let's get the scanner out of the way first scanner

the scanner out of the way first scanner scanner equals new scanner we need a

scanner equals new scanner we need a scanner to accept user input within the

scanner to accept user input within the set of parentheses type

set of parentheses type system.in and then I will just

system.in and then I will just automatically import this class so at

automatically import this class so at the top of your Java file you need this

the top of your Java file you need this import import

import import java.util.scanner then when you open a

java.util.scanner then when you open a scanner it is a good idea to close it at

scanner it is a good idea to close it at the end of your file when you're done

the end of your file when you're done with it because you don't want to leave

with it because you don't want to leave resources open we have our scanner to

resources open we have our scanner to accept user input let's declare some

accept user input let's declare some variables what will we need we will need

variables what will we need we will need the original temperature this will be of

the original temperature this will be of the double data type double temp we'll

the double data type double temp we'll need a new temperature let's say double

need a new temperature let's say double new temp that's after we convert it and

new temp that's after we convert it and a unit we could use Char for the unit

a unit we could use Char for the unit you know the letter F or c for

you know the letter F or c for Fahrenheit or Celsius but just to keep

Fahrenheit or Celsius but just to keep it simple I'm going to use a string

it simple I'm going to use a string because there's a built-in method of two

because there's a built-in method of two uppercase we can take the input and make

uppercase we can take the input and make it uppercase automatically just to make

it uppercase automatically just to make it simple we'll use a string rather than

it simple we'll use a string rather than a Char for the

a Char for the unit okay now we just need to get the

unit okay now we just need to get the temperature we'll need a prompt I'll use

temperature we'll need a prompt I'll use print instead of print line we will ask

print instead of print line we will ask the user to enter the

temperature we will assign the temperature temp equals scanner. next

temperature temp equals scanner. next Double because we're accepting a value

Double because we're accepting a value we're signing a variable of the double

we're signing a variable of the double data type now we need the unit is it

data type now we need the unit is it going to be Celsius or

going to be Celsius or Fahrenheit we'll need another prompt

Fahrenheit we'll need another prompt I'll use print instead of print

I'll use print instead of print line we will ask the user convert to

line we will ask the user convert to Celsius or Fahrenheit

F let's ass our unit variable use our

variable use our scanner then use the next method to get

scanner then use the next method to get the next character we'll use the next

the next character we'll use the next method to get the next

method to get the next character we don't necessarily need next

character we don't necessarily need next line we just want a single

line we just want a single character so check this out I'm going to

character so check this out I'm going to Output our temp

Output our temp and our

unit what if somebody types in a lowercase C or F so let's say the

lowercase C or F so let's say the temperature is

temperature is 75 75° F and we would like to convert it

75 75° F and we would like to convert it to Celsius I'll type lowercase C rather

to Celsius I'll type lowercase C rather than uppercase

C our unit is currently a lowercase C we can convert it to be

can convert it to be uppercase following the next method of

uppercase following the next method of our scanner where we assign our unit

our scanner where we assign our unit we're going to do something called

we're going to do something called method

method chaining we'll add another dot then use

chaining we'll add another dot then use the two uppercase method of

the two uppercase method of strings let's try that again and see if

strings let's try that again and see if it

it works

works 75 I'll type in lower case

C the two uppercase method will take that lowercase C and make it uppercase

that lowercase C and make it uppercase which is what we'll need in this next

which is what we'll need in this next section we can delete these two

section we can delete these two statements now we're going to use the

statements now we're going to use the tary

tary operator how the trary operator works is

operator how the trary operator works is that we check a

that we check a condition followed by a question mark

condition followed by a question mark like we're asking a question we will

like we're asking a question we will return some code if that condition is

return some code if that condition is true colon meaning else if it's false

true colon meaning else if it's false we'll do some other code or return some

we'll do some other code or return some other value we're going to follow this

other value we're going to follow this formula so what is our condition let's

formula so what is our condition let's check to see if our unit is equal to a c

check to see if our unit is equal to a c take our variable of

take our variable of unit use the equals method because

unit use the equals method because strings have a built-in method of

strings have a built-in method of equals does our unit equal in uppercase

equals does our unit equal in uppercase C question mark That's the tary operator

C question mark That's the tary operator we're asking a

we're asking a question if this is true that means

question if this is true that means we're trying to convert from Fahrenheit

we're trying to convert from Fahrenheit to Celsius

to Celsius the formula to do that would be the

the formula to do that would be the following we would be executing this

following we would be executing this code since it's

code since it's true take our temp subtract

true take our temp subtract 32 then multiply 5 /

32 then multiply 5 / 9 now what if our unit does not equal C

9 now what if our unit does not equal C that means we're trying to convert to

that means we're trying to convert to Fahrenheit we'll need that colon for the

Fahrenheit we'll need that colon for the next part of the

next part of the section now here's the formula to

section now here's the formula to convert from Celsius to Fahrenheit

convert from Celsius to Fahrenheit this will be the false section of the

this will be the false section of the trinary

trinary operator take our temp * 5 /

operator take our temp * 5 / 9 +

9 + 32 with the trinary operator how we've

32 with the trinary operator how we've written this code is that we're going to

written this code is that we're going to be returning a double after converting

be returning a double after converting it we need to do something with it so

it we need to do something with it so we're going to assign it to a variable

we're going to assign it to a variable our variable of new temp then we can do

our variable of new temp then we can do something with it

something with it once we have our new temperature let's

once we have our new temperature let's display it I'll perform a test run let's

display it I'll perform a test run let's print our new

print our new temp let's say it's 100° F and we're

temp let's say it's 100° F and we're going to convert to Celsius I'll type in

going to convert to Celsius I'll type in see well the temperature in Celsius is

see well the temperature in Celsius is 37.7 repeating we're going to format

37.7 repeating we're going to format this in a

this in a moment let's add a degree

moment let's add a degree symbol plus a string on Windows to add a

symbol plus a string on Windows to add a degree symbol make sure num lock is on

degree symbol make sure num lock is on hold alt then type

0176 plus our unit we're converting to let's try that

let's try that again what is 100° fah converted to

again what is 100° fah converted to Celsius

Celsius 37.7 repeating de

37.7 repeating de C to limit the amount of digits that

C to limit the amount of digits that display after the decimal we we can use

display after the decimal we we can use a print F statement let's convert our

a print F statement let's convert our print line for the new temp to be print

print line for the new temp to be print F rather than print

F rather than print line we'll add a

placeholder we're displaying a double so we need F to display one digit type 0.1

we need F to display one digit type 0.1 between the percent sign and the

between the percent sign and the F comma new

temp after our placeholder We'll add our degree symbol again I'm holding alt numb

degree symbol again I'm holding alt numb lock is on I'm typing

lock is on I'm typing 0176 then we will display the unit it's

0176 then we will display the unit it's a string percent s for

a string percent s for Strings we're inserting a new variable

Strings we're inserting a new variable we're going to comma separate them then

we're going to comma separate them then add our

add our unit and let me just close this Gap

unit and let me just close this Gap let's see what the final product

let's see what the final product is let's convert

is let's convert 30.1 this will be in Celsius to

30.1 this will be in Celsius to Fahrenheit

Fahrenheit and the temperature in Fahrenheit is

and the temperature in Fahrenheit is 48.7 De

48.7 De fahit okay everybody that is a

fahit okay everybody that is a temperature conversion program that you

temperature conversion program that you can write using the tary operator in

Java why hello there today I got to explain something called enhanced

explain something called enhanced switches in Java in Java there switches

switches in Java in Java there switches and then there's enhanced switches

and then there's enhanced switches enhanced switches are a Java 14 feature

enhanced switches are a Java 14 feature I would recommend using using enhanced

I would recommend using using enhanced switches over standard switches so what

switches over standard switches so what is a switch exactly a switch is a

is a switch exactly a switch is a replacement to using many l statements

replacement to using many l statements here's an example of us using a lot of

here's an example of us using a lot of lse if statements in this sample program

lse if statements in this sample program we have a day of the week I set mine to

we have a day of the week I set mine to be Friday with each of these if

be Friday with each of these if statements I am checking to see if the

statements I am checking to see if the day equals Monday Tuesday so on and so

day equals Monday Tuesday so on and so forth currently my day is set to

forth currently my day is set to Friday this would give me it is a

Friday this would give me it is a weekday

weekday if I set the day to be

if I set the day to be Saturday well then it is the

Saturday well then it is the weekend or Sunday let me show you the

weekend or Sunday let me show you the code it is the weekend then I have an

code it is the weekend then I have an else statement if none of the above

else statement if none of the above conditions are true for example let's

conditions are true for example let's say day is pizza day which doesn't exist

say day is pizza day which doesn't exist but it really

but it really should Pizza day is not a day this code

should Pizza day is not a day this code does work but it could be more efficient

does work but it could be more efficient we have a lot of redundancies we're

we have a lot of redundancies we're using a lot of else if statements that

using a lot of else if statements that all basically do the same

thing an improvement would be to use an enhanced switch let me demonstrate how

enhanced switch let me demonstrate how to make

to make that so let's set our day to be Monday

that so let's set our day to be Monday for example to create a switch we will

for example to create a switch we will type switch at a set of parentheses then

type switch at a set of parentheses then a set of curly

a set of curly braces it's similar to an if statement

braces it's similar to an if statement already with within the set of

already with within the set of parentheses for the switch we're going

parentheses for the switch we're going to examine a value or variable we're

to examine a value or variable we're going to examine our string of day we

going to examine our string of day we will examine this value against any

will examine this value against any matching cases the first case will be a

matching cases the first case will be a string of

string of Monday if day is equal to this value a

Monday if day is equal to this value a string of Monday we'll do

string of Monday we'll do something we'll use an arrow an arrow is

something we'll use an arrow an arrow is the arrow operator in Java think of it

the arrow operator in Java think of it as meaning do something do this if day

as meaning do something do this if day equals Monday do this code so let's

equals Monday do this code so let's print

print something let's print it is a

something let's print it is a weekday and then for fun you don't have

weekday and then for fun you don't have to but I'm going to add an

to but I'm going to add an emoji nobody likes Mondays let's be

emoji nobody likes Mondays let's be honest if day is Monday do this code

honest if day is Monday do this code let's add another case let me zoom in a

let's add another case let me zoom in a little if Case is

little if Case is Tuesday Arrow op operator meaning do

Tuesday Arrow op operator meaning do this code we will print we'll print the

this code we will print we'll print the same thing it is a

same thing it is a weekday we'll do this with the other

weekday we'll do this with the other days too I'll just copy this code then

days too I'll just copy this code then repurpose it to save some time case

repurpose it to save some time case Wednesday it is a

Wednesday it is a weekday case

weekday case Thursday it is a

Thursday it is a weekday case

weekday case Friday it is a weekday now if it's sat

Friday it is a weekday now if it's sat Saturday that means it's the

Saturday that means it's the weekend case

weekend case Saturday it is the weekend let's change

Saturday it is the weekend let's change the

weekend let's perform a test run if you're using intellig you may have These

you're using intellig you may have These Warnings it's basically saying that

Warnings it's basically saying that these sections of code are unreachable

these sections of code are unreachable we're manually setting a variable these

we're manually setting a variable these sections of code are not going to

sections of code are not going to execute so I would just ignore that for

execute so I would just ignore that for now so let's perform a test

now so let's perform a test run my day is Monday day is equal to the

run my day is Monday day is equal to the case of Monday so we do this code if it

case of Monday so we do this code if it were

Friday case Friday we do this code if Case were Saturday

well we do this code and

Sunday case Sunday so we do this code it is the

is the weekend what if we have a day that

weekend what if we have a day that doesn't exist like pizza

day well we can add a default case here's how we'll type the keyword

here's how we'll type the keyword default Arrow meaning do

default Arrow meaning do this we'll print

this we'll print our variable

our variable day plus a string of is not a

day Pizza day is not a day the default case it behaves similarly to your else

case it behaves similarly to your else statement if no above conditions are

statement if no above conditions are true then we will do

true then we will do this so what we'll do now is accept some

this so what we'll do now is accept some user input using a scanner we'll need to

user input using a scanner we'll need to create a scanner object scanner scanner

create a scanner object scanner scanner equals new scanner within the set of

equals new scanner within the set of parentheses type

parentheses type system.in and then I'm just going to

system.in and then I'm just going to automatically import this class at the

automatically import this class at the top of my Java file import

top of my Java file import java.util.scanner

java.util.scanner we'll create a prompt for a user to type

we'll create a prompt for a user to type in the

in the day enter the day of the week and I will

day enter the day of the week and I will use print instead of print line instead

use print instead of print line instead of manually assigning a variable we'll

of manually assigning a variable we'll use our scanner scanner. nextt line to

use our scanner scanner. nextt line to accept a

string okay let's try this again enter the day of the week it is

again enter the day of the week it is Tuesday it is a weekday let's try that

Tuesday it is a weekday let's try that again enter the day of the week it is

again enter the day of the week it is Saturday it is the

Saturday it is the weekend and let's make up a

weekend and let's make up a day uh let's go with taco

day uh let's go with taco day taco day is not a

day taco day is not a day we could actually improve this widg

day we could actually improve this widg even further intellig is saying we have

even further intellig is saying we have a duplicate branch in our switch we have

a duplicate branch in our switch we have two or more cases that are doing the

two or more cases that are doing the same thing we are outputting it is a

weekday we could consolidate some of these cases here's how the cases of

these cases here's how the cases of Monday Tuesday Wednesday Thursday and

Monday Tuesday Wednesday Thursday and Friday they all output the same thing so

Friday they all output the same thing so we're going to consolidate them I'll

we're going to consolidate them I'll copy one of these print statements and

copy one of these print statements and delete all of them

we can comma separate these cases so case Monday

case Monday comma

comma Tuesday

Tuesday comma

comma Wednesday

Wednesday comma

comma Thursday

Thursday comma

comma Friday then Arrow

Friday then Arrow if our case is Monday Tuesday Wednesday

if our case is Monday Tuesday Wednesday Thursday or Friday then do the following

Thursday or Friday then do the following we'll print it is a

we'll print it is a weekday now Saturday and Sunday do the

weekday now Saturday and Sunday do the same thing

same thing too let's cut one of these

too let's cut one of these lines and delete

lines and delete them case

them case Saturday comma

Saturday comma Sunday Arrow meaning do this it is the

Sunday Arrow meaning do this it is the weekend then we'll keep keep our default

weekend then we'll keep keep our default case in case there are no matches let's

case in case there are no matches let's try this

try this again enter the day of the week it is

again enter the day of the week it is Wednesday it is a

Wednesday it is a weekday it is

weekday it is Saturday it is the

Saturday it is the weekend it is Sunday it is the

weekend uh then let's go with uh Hamburger

Hamburger Day hamburger day is not a day

Day hamburger day is not a day so those are enhanced switches they're a

so those are enhanced switches they're a replacement to using many LF

replacement to using many LF statements if you find yourself using a

statements if you find yourself using a lot of lsif statements I would recommend

lot of lsif statements I would recommend using a switch instead but not just any

using a switch instead but not just any switch an enhanced switch which is a

switch an enhanced switch which is a Java 14 feature that you should know

Java 14 feature that you should know about and well everybody those are

about and well everybody those are enhanced switches in

Java what is going on everybody in this video we're going to create a simple

video we're going to create a simple calculator program using what we've

calculator program using what we've learned with enhanced switches this is

learned with enhanced switches this is meant to be more of a practice project

meant to be more of a practice project let's get started the first thing we'll

let's get started the first thing we'll need is a scanner we will create a

need is a scanner we will create a scanner object scanner scanner equals

scanner object scanner scanner equals new scanner within the set of

new scanner within the set of parentheses type

parentheses type system.in and then when you open a

system.in and then when you open a scanner it is a good idea to close it

scanner it is a good idea to close it when you're done with

when you're done with it scanner. close then be sure to import

it scanner. close then be sure to import the class at the top of your Java file

the class at the top of your Java file make sure you have this import import

make sure you have this import import java.util.scanner

java.util.scanner what are the different variables we'll

what are the different variables we'll need a user is going to type in two

need a user is going to type in two numbers and an operator such as a plus

numbers and an operator such as a plus for addition minus for subtraction so on

for addition minus for subtraction so on and so forth the first variable will be

and so forth the first variable will be up the double data type double num

up the double data type double num one double num two then an operator this

one double num two then an operator this will be a Char Char operator

will be a Char Char operator and a result double

result there's going to be one more variable but we'll fill that in later so

variable but we'll fill that in later so we'll stick with these four for now

we'll stick with these four for now we'll prompt a user to type in the first

we'll prompt a user to type in the first number followed by an operator than the

number followed by an operator than the second

second number here's how we can write

number here's how we can write that let's ask the user to enter the

that let's ask the user to enter the first number and I will use print

first number and I will use print instead of print line

we will assign num one equal to use our scanner to get user

scanner to get user input next

Double then we need the operator we will use a print

use a print statement enter n

statement enter n operator we'll have Plus for addition

operator we'll have Plus for addition minus for subtraction an asterisk for

minus for subtraction an asterisk for multiplication a for slash for division

multiplication a for slash for division let's add one more let's add a carrot

let's add one more let's add a carrot this will raise a base to a given

this will raise a base to a given power feel free to add more if you would

power feel free to add more if you would like but we'll just stick with these

like but we'll just stick with these five a user is going to enter in a

five a user is going to enter in a character one of these operators

character one of these operators hopefully we will assign our variable of

hopefully we will assign our variable of operator equal to

operator equal to scanner.

next the next method will give you a string we can method chain the Char at

string we can method chain the Char at method to return a single character when

method to return a single character when a user types in something just give me

a user types in something just give me the first character this will also

the first character this will also convert it to be a character rather than

convert it to be a character rather than keep it a

keep it a string so ideally our operator is going

string so ideally our operator is going to be a plus a minus an asterisk a

to be a plus a minus an asterisk a forward slash or a

forward slash or a carrot then we need num two we can just

carrot then we need num two we can just copy these two lines paste them change

copy these two lines paste them change first to be second and num one to be num

first to be second and num one to be num two we have our two numbers and our

two we have our two numbers and our operator we have to determine what the

operator we have to determine what the operator is we can use an enhanced

operator is we can use an enhanced switch for that we will create a

switch for that we will create a switch within the set of

switch within the set of parentheses we are examining our

parentheses we are examining our operator we're examining our operator

operator we're examining our operator against any matching cases the first

against any matching cases the first case will be a plus sign and these cases

case will be a plus sign and these cases are going to be within single quotes not

are going to be within single quotes not double quotes because we're working with

double quotes because we're working with a character not a

a character not a string with our switch if our operator

string with our switch if our operator is a plus character we're going to write

is a plus character we're going to write an arrow meaning do

an arrow meaning do this we will take our variable of

this we will take our variable of result set it equal to be num one that's

result set it equal to be num one that's the first number plus num two

the first number plus num two that will be the case for addition then

that will be the case for addition then we have

we have subtraction case minus Arrow do this

subtraction case minus Arrow do this assign our result equal to num one minus

assign our result equal to num one minus num

num 2 multiplication would be

2 multiplication would be case a character vaster risk arrow take

case a character vaster risk arrow take our result equals num one * num

two now for division we have a forward

we have a forward slash arrow take our result equals num

slash arrow take our result equals num one divided by num

one divided by num two now with division if somebody

two now with division if somebody divides by zero we'll return to this

divides by zero we'll return to this case later and make it a little more

case later and make it a little more sophisticated where we check to see if

sophisticated where we check to see if num 2 is zero I would like for us to get

num 2 is zero I would like for us to get a solid foundation first for this

a solid foundation first for this program so if somebody would like to

program so if somebody would like to raise a base to a given power we will

raise a base to a given power we will use the

carrot we will assign our result equal to now we're going to use the math

to now we're going to use the math class the power method of the math class

class the power method of the math class we can raise a base to a given power we

we can raise a base to a given power we will raise num one to the power of num

two let's perform a test run just to be sure that it

sure that it works I'm going to display our result

works I'm going to display our result after the

after the switch so Java is giving us a warning

switch so Java is giving us a warning that variable result might not have been

that variable result might not have been initialized that's because it's possible

initialized that's because it's possible there's no matching

there's no matching cases and we would be keeping our result

cases and we would be keeping our result uninitialized so to clear that up when

uninitialized so to clear that up when we declare our variable we can also

we declare our variable we can also assign it I'll just set it to be

assign it I'll just set it to be zero let's perform a test

run enter the first number let's do 3.14 enter an operator let's do addition

3.14 enter an operator let's do addition and the second number

and the second number 1.1 the result is

1.1 the result is 4.24 let's do subtraction

4.24 let's do subtraction 3.14 minus 1.1 which gives us

3.14 minus 1.1 which gives us 2.04

2.04 multiplication

multiplication 3.14 times let's do

3.14 times let's do two

divided by two that gives us

two that gives us 1.57 then we have power what is

1.57 then we have power what is 3 to the power of

3 to the power of three that is

three that is 27 3 * 3 is 9 * 3 is 27 3 ^ of

27 3 * 3 is 9 * 3 is 27 3 ^ of 3 we have one potential issue though

3 we have one potential issue though what if somebody divides by zero here's

what if somebody divides by zero here's what happens

what happens what is

what is 3.14 /

3.14 / 0 we get the output of

0 we get the output of infinity here's how we could prevent

infinity here's how we could prevent that underneath the case where we do

that underneath the case where we do division we'll write a few lines rather

division we'll write a few lines rather than just one but we're going to enclose

than just one but we're going to enclose them within a set of curly

them within a set of curly braces then I'm going to cut this line

braces then I'm going to cut this line of

of code within this case we'll write an if

code within this case we'll write an if statement we'll

statement we'll check

check if num 2 is equal to

if num 2 is equal to zero that's because we can't normally

zero that's because we can't normally divide by zero if it is then let's print

divide by zero if it is then let's print cannot divide by

zero else we'll assign our result of num one

else we'll assign our result of num one / by num 2 we'll execute the L statement

/ by num 2 we'll execute the L statement if num 2 doesn't equal zero because if

if num 2 doesn't equal zero because if it did this would be true and we execute

it did this would be true and we execute this code instead let's try that

this code instead let's try that again what is

again what is 3.14 /

3.14 / 0 cannot divide by

0 cannot divide by zero however we still do display a

zero however we still do display a result and that is by using this print

result and that is by using this print statement what if somebody types in an

statement what if somebody types in an operator that doesn't exist 3.14

operator that doesn't exist 3.14 I'm going to type in pizza for the

I'm going to type in pizza for the operator type in I don't know

operator type in I don't know one well we still display a result so

one well we still display a result so let's modify this program let's display

let's modify this program let's display a result only if we have a valid

a result only if we have a valid operator because right now we don't

operator because right now we don't Pizza is not a valid

operator let's add a Boolean variable of valid

valid operation I will set this to be true

operation I will set this to be true from the

beginning if somebody attempts to divide by zero I'm going to take our valid

by zero I'm going to take our valid operation variable and set it to be

operation variable and set it to be false because we do not want to continue

false because we do not want to continue and display the

result we're going to add a default case the default case will be the

following so I'm going to write two lines of code for the default

lines of code for the default case let's

case let's output invalid

operator then we will take our Boolean variable of valid operation and set it

variable of valid operation and set it to be

to be false so this is what our switch looks

false so this is what our switch looks like feel free to pause the video if you

like feel free to pause the video if you would like a moment to look it

would like a moment to look it over within our case of division we do

over within our case of division we do have a few lines of code same thing

have a few lines of code same thing applies with the default

applies with the default case we're only going to print the

case we're only going to print the result if our Boolean of valid operation

result if our Boolean of valid operation is

is true if valid operation is equal to true

true if valid operation is equal to true but really we can just shorten this to

but really we can just shorten this to if valid

if valid operation then we'll print the

operation then we'll print the result then we don't necessarily need an

result then we don't necessarily need an else

else statement because we're already printing

statement because we're already printing either invalid operator or cannot divide

either invalid operator or cannot divide by zero

by zero okay let's run this one final

okay let's run this one final time

time 3.14 plus

3.14 plus 2.1 is

2.1 is 5.24

5.24 3.14

3.14 minus 1.1 is

3.14 time 2.1 is 6594

2.1 is 6594 4

4 3.14 okay 3.14 / 0 Let's see what

3.14 okay 3.14 / 0 Let's see what happens cannot divide by zero and we do

happens cannot divide by zero and we do not display the result because our

not display the result because our equation is invalid which is good we

equation is invalid which is good we don't want to display the result we're

don't want to display the result we're displaying a type of error message

instead let's raise 4 to the

4 to the power of two which gives us

power of two which gives us 16 now let's type in an operator that

16 now let's type in an operator that doesn't exist

3.14 Pizza

Pizza 69 invalid operator that's because Pizza

69 invalid operator that's because Pizza is not a valid

is not a valid operator all right everybody that is a

operator all right everybody that is a calculator program that you can write

calculator program that you can write the purpose of this program is to more

the purpose of this program is to more or less help us with enhanced switch

or less help us with enhanced switch statements depending on the operator we

statements depending on the operator we can perform one of a few operations

can perform one of a few operations we've also learned that your cases can

we've also learned that your cases can take up more than one line if you would

take up more than one line if you would like and well everybody that is a

like and well everybody that is a calculator program in

Java yo yo yo in today's video I'm going to explain logical operators in Java

to explain logical operators in Java logical operators they allow us to check

logical operators they allow us to check or modify more than one condition

or modify more than one condition there's and or not we'll discuss and

there's and or not we'll discuss and first which is represented by two Amper

first which is represented by two Amper Sands let's declare a variable of

Sands let's declare a variable of temperature temp meaning temperature I

temperature temp meaning temperature I will set this to be 20 I would like to

will set this to be 20 I would like to check to see if my temperature Falls

check to see if my temperature Falls within a certain range well to do that I

within a certain range well to do that I could use the and logical operator we

could use the and logical operator we can check more than one

can check more than one condition so first I would like to see

condition so first I would like to see if my

if my temp is less than or equal to 30 30°

temp is less than or equal to 30 30° C and if the temp is greater than or

C and if the temp is greater than or equal to zero

equal to zero we have two conditions this time if this

we have two conditions this time if this is true and this is true then do this

is true and this is true then do this code so let's output the

code so let's output the following if our temperature Falls

following if our temperature Falls within this range we'll

within this range we'll output the weather is good and for fun

output the weather is good and for fun I'll let a smiley face cuz why not okay

I'll let a smiley face cuz why not okay let's see how this works the temperature

let's see how this works the temperature is currently 20 20° C

is currently 20 20° C the weather is good if the temperature

the weather is good if the temperature were 40 40°

were 40 40° C well we don't do

C well we don't do anything this condition evaluated to be

anything this condition evaluated to be false but this one is true our

false but this one is true our temperature is greater than or equal to

temperature is greater than or equal to zero that is true but this one is false

zero that is true but this one is false and using the and logical operator both

and using the and logical operator both conditions must be true in order for

conditions must be true in order for this entire statement to be true

this entire statement to be true since only one of them was true where

since only one of them was true where temp is greater than or equal to zero we

temp is greater than or equal to zero we don't execute this code the and logical

don't execute this code the and logical operator is used to check more than one

operator is used to check more than one condition we can add as many as we would

condition we can add as many as we would like to this time let's create a

like to this time let's create a variable of is sunny this will be a

variable of is sunny this will be a Boolean Boolean is sunny is it sunny

Boolean Boolean is sunny is it sunny outside I will set that to be

outside I will set that to be true not only are we going to check to

true not only are we going to check to see if our temperature is within a

see if our temperature is within a certain range we're also going to check

certain range we're also going to check and is sunny is this true so now we are

and is sunny is this true so now we are linking three different conditions all

linking three different conditions all three must be true so if all three are

three must be true so if all three are true we'll outut the following it is

true we'll outut the following it is sunny

outside let's set is sunny to be false and then we are going to set our

and then we are going to set our temperature to not

temperature to not 240

20 these two conditions are true but this one is false so we don't do any of

this one is false so we don't do any of it we skip over it with the and logical

it we skip over it with the and logical operator all conditions must be

operator all conditions must be true if is sunny we're true

true if is sunny we're true then well then we execute this code the

then well then we execute this code the temperature Falls within this range this

temperature Falls within this range this is true and this this is true and this

is true and this this is true and this is true all three conditions are true so

is true all three conditions are true so we execute this code the weather is good

we execute this code the weather is good and it is sunny

and it is sunny outside we check more than one condition

outside we check more than one condition and both must be true there's also the

and both must be true there's also the not logical operator it's a little

not logical operator it's a little different how it works is that it gives

different how it works is that it gives you the opposite you can check to see if

you the opposite you can check to see if something is not true let's add an elive

something is not true let's add an elive statement we're going to copy these

statement we're going to copy these three conditions but make one change

three conditions but make one change we're going to precede is Sunny with the

we're going to precede is Sunny with the not logical operator represented by an

not logical operator represented by an exclamation

exclamation point it checks the opposite we are

point it checks the opposite we are checking to see if something is not true

checking to see if something is not true is our temperature less than or equal to

is our temperature less than or equal to 30 and greater than or equal to zero and

30 and greater than or equal to zero and is it not

is it not Sunny so if something is normally false

Sunny so if something is normally false using the not logical operator it

using the not logical operator it becomes true if it's normally true it

becomes true if it's normally true it becomes false it gives you the opposite

becomes false it gives you the opposite for a Boolean value

for a Boolean value basically if the weather is good but

basically if the weather is good but it's not Sunny that must mean it's

it's not Sunny that must mean it's cloudy it is cloudy outside then I'll

cloudy it is cloudy outside then I'll add an emoji of a

cloud the temperature is good but we'll set is sunny to be

false the weather is good but it is cloudy

good but it is cloudy outside the temperature Falls within

outside the temperature Falls within this

this range and it is not

range and it is not Sunny the not logical operator checks to

Sunny the not logical operator checks to see if something is not true then we

see if something is not true then we have the or logical operator represented

have the or logical operator represented by two vertical bars or is similar to

by two vertical bars or is similar to the and logical operator however only

the and logical operator however only one condition needs to be true that are

one condition needs to be true that are linked by the or logical operator with

linked by the or logical operator with and both must be true let's say our

and both must be true let's say our temperature is really cold it is -10°

temperature is really cold it is -10° C but it is sunny

outside we actually don't end up doing anything we skip over the if statement

anything we skip over the if statement and the else if statement let's add

and the else if statement let's add another LF

another LF statement we're going to check to see if

statement we're going to check to see if our temperature is really hot or really

our temperature is really hot or really cold we will check if our temp is

cold we will check if our temp is greater than 30

greater than 30 or using two vertical bars temp is less

or using two vertical bars temp is less than

than zero then we'll

bad if our temperature is -10 the weather is bad with the or

-10 the weather is bad with the or logical operator at least one condition

logical operator at least one condition must be true this condition was false

must be true this condition was false but this one was true so we execute this

but this one was true so we execute this code because using the or logical

code because using the or logical operator at least one condition needs to

operator at least one condition needs to be

be true or if the temperature was 35 35°

true or if the temperature was 35 35° C this time this condition was true but

C this time this condition was true but this one was false so we execute this

this one was false so we execute this code all right let's go over another

code all right let's go over another example we're going to use these logical

example we're going to use these logical operators to validate a username when

operators to validate a username when somebody tries to set a

somebody tries to set a username so in this project we'll need a

username so in this project we'll need a scanner scanner scanner equals new

scanner scanner scanner equals new scanner we're going to type

scanner we're going to type system.in then import this

system.in then import this class then be sure to close your scanner

class then be sure to close your scanner at the end of the file scanner.

close our username has a few rules I'll add these as comments

rules I'll add these as comments username must be between 4 through 12

characters username must not

not contain

contain spaces or

underscores we'll create a string variable of

variable of username we'll create a prompt to have a

username we'll create a prompt to have a user enter in a

username enter your new username I'll use print instead of print

username I'll use print instead of print line we will assign our username using

line we will assign our username using the scanner username equals scanner.

the scanner username equals scanner. next

line we'll write a condition to check if our username is between 4 to 12

our username is between 4 to 12 characters we're going to check if our

characters we're going to check if our username is under four characters or

username is under four characters or greater than 12 characters we'll check

greater than 12 characters we'll check that within an if

that within an if statement if our username

statement if our username use the length method to return the

use the length method to return the length of this string if the length of

length of this string if the length of our username is less than four use the

our username is less than four use the or logical operator or our

or logical operator or our username the length of it using the

username the length of it using the length method is greater than 12 that

length method is greater than 12 that means our username is too short or too

means our username is too short or too long we'll output the following username

long we'll output the following username must be between 4 through 12 characters

must be between 4 through 12 characters let's perform a test

let's perform a test run enter your new username I'll type in

run enter your new username I'll type in something that's less than four

something that's less than four characters username must be between 4 to

characters username must be between 4 to 12

12 characters let's type in a really long

characters let's type in a really long username I'll just make up something

username I'll just make up something username must be between 4 to 12

username must be between 4 to 12 characters let's type in something

characters let's type in something actually within that

range oh and then we need to add an lse state statement because I

state statement because I forgot else we will

forgot else we will print

print welcome plus

username welcome whatever your username is the second part of this assignment is

is the second part of this assignment is that we need to check to make sure that

that we need to check to make sure that there are no spaces or underscores

there are no spaces or underscores within our username after the if

within our username after the if statement We'll add an L if statement to

statement We'll add an L if statement to check

check that using the contains method of

that using the contains method of strings we can check if a string

strings we can check if a string contains a certain character with our

contains a certain character with our username we will use the contains method

username we will use the contains method does our username contain any

does our username contain any spaces or does our

spaces or does our username

username contains any

contains any underscores if so we'll output the

underscores if so we'll output the following user usame must

following user usame must not contain spaces or

underscores let's perform another test run type in your first and last name

run type in your first and last name including a space username must not

including a space username must not contain spaces or

contain spaces or underscores this time I will use an

underscores this time I will use an underscore to separate the first and

underscore to separate the first and last

last name username must not contain spaces or

name username must not contain spaces or underscores let's type in a usern name

underscores let's type in a usern name that follows the

that follows the rules that seems to

rules that seems to work so that is the or logical operator

work so that is the or logical operator if at least one condition is true then

if at least one condition is true then the entire statement is true and we

the entire statement is true and we execute it all right everybody so those

execute it all right everybody so those are logical operators and checks more

are logical operators and checks more than one condition both must be true or

than one condition both must be true or checks more than one condition at least

checks more than one condition at least one needs to be true not not is a little

one needs to be true not not is a little different it checks if something is not

different it checks if something is not true basically does the inverse and well

true basically does the inverse and well everybody those are logical operators in

Java what is going on everybody in this video I need to explain while Loops in

video I need to explain while Loops in Java if I could summarize a while loop

Java if I could summarize a while loop in one sentence a while loop will repeat

in one sentence a while loop will repeat some code Forever while some condition

some code Forever while some condition remains true first I'll give you a

remains true first I'll give you a demonstration using an if statement then

demonstration using an if statement then we'll convert it to be a while loop and

we'll convert it to be a while loop and we'll see how it's useful we'll need to

we'll see how it's useful we'll need to accept user input in this demonstration

accept user input in this demonstration I will create a scanner I'm pretty sure

I will create a scanner I'm pretty sure we know how to create one by

we know how to create one by now be assured to import the scanner

now be assured to import the scanner class import java.util.scanner then be

class import java.util.scanner then be sure to close your scanner because I

sure to close your scanner because I always forget to do

always forget to do that all right we are going to create a

that all right we are going to create a string of

string of name I'll use an if statement to check

name I'll use an if statement to check to see if my name is

to see if my name is empty if name use the is empty method

empty if name use the is empty method now Java wants us to assign this name

now Java wants us to assign this name right away okay so I'm going to go ahead

right away okay so I'm going to go ahead and initialize it we can initialize it

and initialize it we can initialize it with an empty space if our name is empty

with an empty space if our name is empty which it will be we will prompt the user

which it will be we will prompt the user to enter your name I'll use print

to enter your name I'll use print instead of print line to keep it on the

instead of print line to keep it on the same line then we will assign our

same line then we will assign our variable of name name equals scanner.

variable of name name equals scanner. next

next line after we escape the if statement

line after we escape the if statement we'll output our name let's say hello

we'll output our name let's say hello Plus

Plus name so this program will work but

name so this program will work but there's one issue what if I don't type

there's one issue what if I don't type in anything when I enter my name I'll

in anything when I enter my name I'll just hit

just hit enter well we still continue with the

enter well we still continue with the rest of the program the output is hello

rest of the program the output is hello we don't display a name because we

we don't display a name because we didn't type in anything how can we

didn't type in anything how can we prevent people from doing stuff like

prevent people from doing stuff like this skipping

this skipping prompts well we could use a while loop

prompts well we could use a while loop rather than an if statement replace if

rather than an if statement replace if with while

with while what we're doing is while this condition

what we're doing is while this condition remains true continue this code Forever

remains true continue this code Forever Until this condition is no longer true

Until this condition is no longer true let's try that

let's try that again enter your name I'm just going to

again enter your name I'm just going to hit enter enter your name no enter your

hit enter enter your name no enter your name no enter your name no okay I give

name no enter your name no okay I give up I'll type in my name then we escape

up I'll type in my name then we escape the while loop hello your

the while loop hello your name so that's why a while loop Loop is

name so that's why a while loop Loop is useful we can repeat some code possibly

useful we can repeat some code possibly Forever at times we may not want a user

Forever at times we may not want a user to continue without doing something a

to continue without doing something a while loop would be really helpful for

while loop would be really helpful for that they would be stuck until this

that they would be stuck until this condition is no longer true at the end

condition is no longer true at the end of your while loop we go back to the

of your while loop we go back to the beginning to check the condition if the

beginning to check the condition if the condition is no longer true then we

condition is no longer true then we escape the while loop and move on with

escape the while loop and move on with the rest of the program there's one

the rest of the program there's one thing you should be cautious of though

thing you should be cautious of though and that is an infinite Loop let me give

and that is an infinite Loop let me give you a

you a demonstration with our while loop if we

demonstration with our while loop if we have a condition that we can't change

have a condition that we can't change from within the loop that's called an

from within the loop that's called an infinite Loop so let's say while the

infinite Loop so let's say while the number one is equal to 1 even my IDE

number one is equal to 1 even my IDE intellig is giving me a warning that 1

intellig is giving me a warning that 1 is equal to 1 is not updated inside the

is equal to 1 is not updated inside the loop I would not recommend following me

loop I would not recommend following me along for this part your computer might

along for this part your computer might freeze up but I'm going to print

freeze up but I'm going to print help I'm stuck in a loop

help I'm stuck in a loop within this while loop I have no way to

within this while loop I have no way to change it from inside of it so we're

change it from inside of it so we're going to be stuck in this while loop

going to be stuck in this while loop forever here's a

demonstration we're just going to print this code

this code forever let's check back later one

forever let's check back later one eternity later it's still going we're

eternity later it's still going we're stuck in a loop this may happen to you

stuck in a loop this may happen to you if you have some condition that you

if you have some condition that you can't change within your while loop

can't change within your while loop you'll need some way to update your

you'll need some way to update your condition

let me give you another example again we'll need our

scanner we're going to pretend that we're playing a game for a user to quit

we're playing a game for a user to quit they have to press the q key we will

they have to press the q key we will declare a string of

declare a string of response we'll use a while

response we'll use a while loop now for my condition for us to be

loop now for my condition for us to be able to escape the while

able to escape the while loop our response I'm going to use the

loop our response I'm going to use the not logical

not logical operator

operator equals a capital Q and this will be a

equals a capital Q and this will be a string so while our response does not

string so while our response does not equal Q we continue the loop forever in

equal Q we continue the loop forever in order for somebody to escape this game

order for somebody to escape this game they have to press Q to quit Java wants

they have to press Q to quit Java wants me to assign this variable right away

me to assign this variable right away and initialize it so I'll do so we don't

and initialize it so I'll do so we don't want our variable to be empty when we

want our variable to be empty when we use it to check a condition

use it to check a condition then intellig is giving us another

then intellig is giving us another warning that our response is not updated

warning that our response is not updated inside the loop if we don't update it

inside the loop if we don't update it we'll be stuck in an infinite

we'll be stuck in an infinite Loop let's pretend that we're playing a

Loop let's pretend that we're playing a game you are playing a

game then we'll output

output press Q to quit

then we will need to update our response response equals use our scanner for

response equals use our scanner for Single Character we can use

Single Character we can use next in case somebody types in a

next in case somebody types in a lowercase que we'll follow this method

lowercase que we'll follow this method with the two uppercase

with the two uppercase method if a user was to type in a

method if a user was to type in a lowercase Q we'll convert it to be an

lowercase Q we'll convert it to be an uppercase q so that it

uppercase q so that it matches once we escape the while loop

matches once we escape the while loop we'll

we'll print you have have quit the

game okay let's perform a test run you are playing a game press Q to

run you are playing a game press Q to quit no

quit no yes

yes okay as long as our response does not

okay as long as our response does not equal Q we are still playing our

equal Q we are still playing our imaginary

game in order for us to quit to escape the while loop we have to press Q to

the while loop we have to press Q to quit I will press q and we escape the

quit I will press q and we escape the loop you have quit the

loop you have quit the game while our response using the not

game while our response using the not logical operator while our response does

logical operator while our response does not equal Q continue the loop forever

not equal Q continue the loop forever let's go over another example we'll ask

let's go over another example we'll ask a user for their

a user for their age int age I will set this to be zero

age int age I will set this to be zero right

right away we'll prompt a user to enter in

away we'll prompt a user to enter in their age enter your

their age enter your age we will assign our age

age we will assign our age variable AG equal scanner. next

variable AG equal scanner. next int then at the end of this program I

int then at the end of this program I will

will print you are our variable

print you are our variable age plus years

old let's say I would like to prevent somebody from typing in a negative

somebody from typing in a negative number like -1 you are ne1 years old

number like -1 you are ne1 years old well we could use a while loop to

well we could use a while loop to reprompt the user before displaying the

reprompt the user before displaying the result so after we assign our age once

result so after we assign our age once let's use a while

let's use a while loop while age is less than zero we'll

loop while age is less than zero we'll output the

following your age can't be negative then we'll reprompt the user again we

then we'll reprompt the user again we can just copy these two lines and then

can just copy these two lines and then paste them within the while loop we'll

paste them within the while loop we'll ask the user to enter in their age again

ask the user to enter in their age again and reassign

and reassign it if we keep on typing negative

it if we keep on typing negative numbers we can't escape the while

numbers we can't escape the while loop we're stuck until we type in

loop we're stuck until we type in something that's

valid you are 21 years old that's a valid

valid number from the beginning if I type in

number from the beginning if I type in something that's valid we don't enter

something that's valid we don't enter the while loop at all it is possible to

the while loop at all it is possible to skip over

skip over it we check the condition of a while

it we check the condition of a while loop before entering it if we type in a

loop before entering it if we type in a number that's valid let's say ages

number that's valid let's say ages 25 we check the condition it's false

25 we check the condition it's false from the beginning so we don't enter the

from the beginning so we don't enter the while loop at all we skip over it and go

while loop at all we skip over it and go straight to the end in this program we

straight to the end in this program we only get caught in the while loop if we

only get caught in the while loop if we type in user input that's not

type in user input that's not valid there's a variation of the while

valid there's a variation of the while loop known as a do while loop we do some

loop known as a do while loop we do some code first and then check the

code first and then check the condition if I was to convert this code

condition if I was to convert this code to be a do while loop I would cut the

to be a do while loop I would cut the while part do this code then check the

while part do this code then check the condition at the

condition at the end this is how the program would run

end this is how the program would run now it's going to be a little bit

different your age can't be negative enter your age I am years old your age

enter your age I am years old your age can't be negative enter your age you are

can't be negative enter your age you are whatever your age is years old so with

whatever your age is years old so with the do while loop we do this code first

the do while loop we do this code first and then check the condition at the end

and then check the condition at the end where it's different compared to a

where it's different compared to a standard while loop is that with the

standard while loop is that with the standard while

standard while loop you may not enter the while loop at

loop you may not enter the while loop at all if this condition is false but with

all if this condition is false but with the do while loop you always do this

the do while loop you always do this code at least once and then check the

code at least once and then check the condition at the end let's go over one

condition at the end let's go over one last example with the do while loop

last example with the do while loop we'll prompt a user to type in a number

we'll prompt a user to type in a number that's between a certain range we will

that's between a certain range we will have int number and I will assign this

have int number and I will assign this to be zero right

to be zero right away let's use a basic while loop

away let's use a basic while loop first

first while our number is less than one we'll

while our number is less than one we'll use the or logical operator to check or

use the or logical operator to check or if our number is greater than 10

if our number is greater than 10 then do

this prompt the user to enter a number between 1 through

10 then we will assign our variable of number equals use our scanner use the

number equals use our scanner use the next int

next int method and then at the end we will print

method and then at the end we will print our

our number you picked

plus number so let's run this our number is

number so let's run this our number is set to

zero enter a number between 1 and 10 let's do negative

let's do negative 1 11 -2 one

1 11 -2 one kajillion I think I broke it okay I'll

kajillion I think I broke it okay I'll type in something that's valid like five

type in something that's valid like five you picked

you picked five rather than check the the condition

five rather than check the the condition from the beginning we could check it at

from the beginning we could check it at the end so let's convert the while loop

the end so let's convert the while loop to a do while loop do this code once and

to a do while loop do this code once and then check the

similarly so do this code once check the condition at the

condition at the end all right everybody so those are

end all right everybody so those are while Loops they allow you to execute

while Loops they allow you to execute some code possibly forever while some

some code possibly forever while some condition remains true they're really

condition remains true they're really useful when accepting user input because

useful when accepting user input because the user might not type in something

the user might not type in something that's valid and you have to keep on

that's valid and you have to keep on repr prompting them that's one good use

repr prompting them that's one good use there's two variations of while Loops a

there's two variations of while Loops a standard while loop and a do while

standard while loop and a do while loop it depends if you want to check the

loop it depends if you want to check the condition before entering the loop and

condition before entering the loop and well everybody those are while Loops in

well everybody those are while Loops in Java

hello everybody in today's video we're going to create a number guessing game

going to create a number guessing game using Java let's get started in this

using Java let's get started in this program we'll be using random numbers

program we'll be using random numbers we'll need to create a random object

we'll need to create a random object random random equals new

random random equals new random then import this class so at the

random then import this class so at the top of our Java file import

top of our Java file import java.util random this random object can

java.util random this random object can Generate random numbers for us we'll

Generate random numbers for us we'll also accept user input we'll need a

also accept user input we'll need a scanner scanner scanner equals new

scanner scanner scanner equals new scanner then within the set of

scanner then within the set of parentheses type

parentheses type system.in then import this class as well

system.in then import this class as well import

import java.util.scanner we have a random

java.util.scanner we have a random object to Generate random numbers and a

object to Generate random numbers and a scanner object to accept user

scanner object to accept user input what are the different variables

input what are the different variables we'll need we'll need the following an

we'll need we'll need the following an integer to hold our

integer to hold our guess so let's say we're going to guess

guess so let's say we're going to guess a random number between 1 and 100 we'll

a random number between 1 and 100 we'll use the scanner to accept an integer and

use the scanner to accept an integer and place it within this variable of

place it within this variable of guess for example the guess might be

guess for example the guess might be 50 we need to keep track of the amount

50 we need to keep track of the amount of attempts it took a user to get the

of attempts it took a user to get the correct number int attempts we'll assign

correct number int attempts we'll assign these

these later and we'll need a random number int

later and we'll need a random number int random number

random number let's go ahead and assign this right

let's go ahead and assign this right away to generate a random number we're

away to generate a random number we're going to use our random

going to use our random object use the next int method of a

object use the next int method of a random object within this method we can

random object within this method we can list two numbers a range if I would like

list two numbers a range if I would like a number between let's say 1 and 10 my

a number between let's say 1 and 10 my two numbers would be 1 comma 11 the

two numbers would be 1 comma 11 the first number is inclusive the second

first number is inclusive the second number is

number is exclusive let's perform a test run of a

exclusive let's perform a test run of a random number I just want to be sure

random number I just want to be sure that it's generating correctly when

that it's generating correctly when writing a program it is a good idea to

writing a program it is a good idea to test your code every once in a while

test your code every once in a while just to be sure that everything is

just to be sure that everything is working so we should get random numbers

working so we should get random numbers between 1 and 10 1 10 5 8 good enough a

between 1 and 10 1 10 5 8 good enough a random number stores a random number

random number stores a random number after generating

after generating it let's create a welcome message let's

it let's create a welcome message let's say number guessing

say number guessing game we will prompt the

game we will prompt the user guess a

user guess a number

number between let's start with 1 through 10

between let's start with 1 through 10 later on we'll increase it to

100 now we'll need a while loop but not just any while loop we'll create a do

just any while loop we'll create a do while loop so do this code once while

while loop so do this code once while this condition remains true and let me

this condition remains true and let me zoom in a little

zoom in a little bit so what's our condition going to be

bit so what's our condition going to be we're going to continue playing this

we're going to continue playing this game while our

game while our guess does not equal our random number

guess does not equal our random number we'll keep on playing until we get the

we'll keep on playing until we get the random number exclamation point equals

random number exclamation point equals means not equal so if our guess does not

means not equal so if our guess does not equal our random number this return

equal our random number this return turns true then we want to keep playing

turns true then we want to keep playing while our guess doesn't equal the random

while our guess doesn't equal the random number within this do while

number within this do while loop will prompt the user to enter in

loop will prompt the user to enter in their guess I'm going to use print line

their guess I'm going to use print line instead of print for guess a number

instead of print for guess a number between 1 and

between 1 and 10 now we'll prompt the user to enter a

10 now we'll prompt the user to enter a number enter a guess enter a

number enter a guess enter a guess for this I'll use print instead of

guess for this I'll use print instead of print line we will assign Our Guest

print line we will assign Our Guest variable equal to use our scanner use

variable equal to use our scanner use the next int

method we're also keeping track the amount of attempts it takes a user to

amount of attempts it takes a user to get the correct

get the correct number so we can increment attempts by

number so we can increment attempts by adding

Plus+ and let's go ahead and initialize attempts we'll set that to be zero

temporarily outside the while loop I'm going to

going to print you have

print you have one my random number right now is only

one my random number right now is only between 1 and 10 I'm just going to keep

between 1 and 10 I'm just going to keep guessing until we get the right

number so I'll just start with one and go all the way to

10 the answer was nine we escaped the wild

wild Loop so we know that this is working

Loop so we know that this is working currently one thing this program is

currently one thing this program is missing is that we'll want to give a

missing is that we'll want to give a user a clue if their guess is too low or

user a clue if their guess is too low or too high because we have no way to

too high because we have no way to tell I'm just typing in random numbers

tell I'm just typing in random numbers and I have no clue how close I am to the

and I have no clue how close I am to the actual number that we need to

actual number that we need to guess let's get rid of this print

guess let's get rid of this print statement we were using it for testing

statement we were using it for testing purposes within the do while loop we'll

purposes within the do while loop we'll write an if statement we'll check if our

write an if statement we'll check if our guess is less than our random

guess is less than our random number that means we guess too

number that means we guess too low if that's the case we'll output the

low if that's the case we'll output the following two low try

again else if our guess is greater than our random

if our guess is greater than our random number that means we guess too

number that means we guess too high too high try

high too high try again if our guess isn't lower than our

again if our guess isn't lower than our random number and our guess isn't

random number and our guess isn't greater than our random number that

greater than our random number that means our guess must equal the random

means our guess must equal the random number so if that's the case we would be

number so if that's the case we would be executing this lse statement because the

executing this lse statement because the preceding two conditions would be false

preceding two conditions would be false that means we have the right answer the

that means we have the right answer the right guess so we'll output the

correct the let me zoom out the number

out the number was plus our random

number and then we'll display the amount of attempts it

of attempts it took number of attempts

took number of attempts plus our variable of attempts after each

plus our variable of attempts after each guess we increment it by

guess we increment it by one the last thing I'm forgetting is to

one the last thing I'm forgetting is to close my scanner because I always forget

close my scanner because I always forget to close

to close it scanner.

it scanner. close okay let's perform a test run

close okay let's perform a test run we're only guessing a number between 1

we're only guessing a number between 1 and 10

and 10 currently I'll guess something right in

currently I'll guess something right in the middle five too low try again the

the middle five too low try again the random number we have to guess should be

random number we have to guess should be between 5 and 10 then I'll go with seven

between 5 and 10 then I'll go with seven too low 8 too low nine too low okay it

too low 8 too low nine too low okay it must be 10 then correct the number was

must be 10 then correct the number was 10 number of attempts it took

10 number of attempts it took five we're going to improve this code

five we're going to improve this code now what if we would like the numbers 1

now what if we would like the numbers 1 through 100 this time well we could make

through 100 this time well we could make this program a little more flexible

this program a little more flexible instead of hardcoding these numbers

instead of hardcoding these numbers within the next integer method we'll

within the next integer method we'll Place some variables here instead we

Place some variables here instead we will create int Min equals whatever you

will create int Min equals whatever you want the minimum to be let's say one int

want the minimum to be let's say one int Max I will set the max to be 100 let's

Max I will set the max to be 100 let's replace these two

replace these two numbers the first one will be Min comma

numbers the first one will be Min comma Max so these variables behave as if they

Max so these variables behave as if they were these numbers within this range the

were these numbers within this range the second number is exclusive so TW include

second number is exclusive so TW include 100 I'm going to add +

100 I'm going to add + one give me the numbers between 1 and

one give me the numbers between 1 and 100 within this print statement let's

100 within this print statement let's use print F

use print F instead we'll replace these numbers with

instead we'll replace these numbers with the format specifier a placeholder we

the format specifier a placeholder we will display an integer so we need D

will display an integer so we need D let's do the same thing with 10

d uh let's do comma Min comma Max and then add a new line at the

end let's do one final run so now we're guessing a number

run so now we're guessing a number between one and 100 I'll guess something

between one and 100 I'll guess something right in the middle too high try again

right in the middle too high try again our numberers going to be between 1 and

our numberers going to be between 1 and 50 then 25 too high 12 too high 6 too

50 then 25 too high 12 too high 6 too high three

high three too low between three and six four

too low between three and six four correct the number was four the number

correct the number was four the number of attempts it took six

of attempts it took six attempts all right everybody so that is

attempts all right everybody so that is a number guessing game that you can

a number guessing game that you can create using

Java hi there everybody so in this video I'm going to explain four Loops in Java

I'm going to explain four Loops in Java a four Loop is similar to a while loop

a four Loop is similar to a while loop however a for Loop executes some code a

however a for Loop executes some code a certain amount of times a for Loop is

certain amount of times a for Loop is different from a while loop a while loop

different from a while loop a while loop could execute an infinite amount of

could execute an infinite amount of times until its condition is no longer

times until its condition is no longer true so with for Loops we want to do

true so with for Loops we want to do something a certain amount of times to

something a certain amount of times to create a for Loop type four parentheses

create a for Loop type four parentheses curly braces now within the condition of

curly braces now within the condition of the for Loop there's three statements

the for Loop there's three statements each is separated with a

each is separated with a semicolon we have statement one

semicolon we have statement one statement two and statement three the

statement two and statement three the first statement is used for ini ization

first statement is used for ini ization we can create a counter to keep track of

we can create a counter to keep track of how many times we have iterated this

how many times we have iterated this Loop basically we're declaring a

Loop basically we're declaring a variable a counter this will be int now

variable a counter this will be int now a common practice for a for Loop is to

a common practice for a for Loop is to create a counter named I meaning index

create a counter named I meaning index in I equal Z or some other number I is

in I equal Z or some other number I is going to be used as a counter within

going to be used as a counter within this Loop also known as a loop control

this Loop also known as a loop control variable the second statement is a

variable the second statement is a condition when do we want to

condition when do we want to stop maybe we would like to execute some

stop maybe we would like to execute some code 10 times we'll continue this loop

code 10 times we'll continue this loop as long as I is less than

as long as I is less than 10 now the third statement the third

10 now the third statement the third statement is the step we can increment

statement is the step we can increment our counter of I by One or another

our counter of I by One or another number or even decrement after each

number or even decrement after each iteration let's increase I by One

iteration let's increase I by One i++ let's perform a test run I'm just

i++ let's perform a test run I'm just going to print the word

pizza so we should execute this code 10 times using this for Loop 1 2 3 4 5 6 7

times using this for Loop 1 2 3 4 5 6 7 8 9

8 9 10 so a for Loop is good if you want to

10 so a for Loop is good if you want to repeat some code a certain amount of

repeat some code a certain amount of times but there's a little bit of setup

times but there's a little bit of setup you have to do we'll need some sort of

you have to do we'll need some sort of index or counter a condition in which

index or counter a condition in which you want to stop and you'll need to

you want to stop and you'll need to update the counter

update the counter one way or another

one way or another initialization condition update we can

initialization condition update we can also print this index of I rather than

also print this index of I rather than printing the word Pizza let's print I to

printing the word Pizza let's print I to see what we're working with during the

see what we're working with during the first iteration I is zero after our Loop

first iteration I is zero after our Loop is complete we increment I by One our

is complete we increment I by One our counter so we have 0 1 2 3 4 5 6 7 8 9

counter so we have 0 1 2 3 4 5 6 7 8 9 We're looping 10 times

We're looping 10 times but we set I to be zero to begin with if

but we set I to be zero to begin with if I were to set I to be 1 and I want to

I were to set I to be 1 and I want to iterate 10 times I could say while I is

iterate 10 times I could say while I is less than or equal to

less than or equal to 10 so now we're starting at 1 and

10 so now we're starting at 1 and counting up to

counting up to 10 we can even decrement

10 we can even decrement to let's set I to be 10 we'll continue

to let's set I to be 10 we'll continue the loop as long as I is greater than

the loop as long as I is greater than zero to decrement we'll set I to be

zero to decrement we'll set I to be minus

minus minus now we're starting at 10 and

decrementing but we're still looping 10 times let's go back to the

beginning using the update statement we can even increment by a certain number

can even increment by a certain number instead of incrementing by one let's

instead of incrementing by one let's increment by two and see what

increment by two and see what happens so this time we start at one and

happens so this time we start at one and update our counter of I two each time or

update our counter of I two each time or even three i+ equal

even three i+ equal 3 1 4 7

3 1 4 7 10 we can decrement by a given

10 we can decrement by a given number let's set I to be 10 we'll

number let's set I to be 10 we'll continue this loop as long as I is

continue this loop as long as I is greater than zero and we will decrement

greater than zero and we will decrement our step we will decrement by 2 i - = 2

our step we will decrement by 2 i - = 2 now we're starting at 10 and

now we're starting at 10 and decrementing by two or even three IUS =

decrementing by two or even three IUS = 3

10741 for this next example we're going to accept user input again we'll need a

scanner import the scanner class and close your scanner at the end

we'll create a prompt enter how many times you want to

Loop I'll create a variable of Max Max will equal use our scanner use the next

will equal use our scanner use the next int

int method and now we're going to create a

method and now we're going to create a loop a for Loop

statements each separated with a semicolon we'll need an index or counter

semicolon we'll need an index or counter to keep track of how many times we have

to keep track of how many times we have looped let's say in I equals

looped let's say in I equals 0 for the next statement what's our

0 for the next statement what's our condition we want to continue as long as

condition we want to continue as long as I is less than the max I is less than

I is less than the max I is less than our Max variable

our Max variable then increment I by

else let's try this how many times do you want to Loop let's Loop five

you want to Loop let's Loop five times 1 2 3 4

times 1 2 3 4 5 again we set I to be zero so that's

5 again we set I to be zero so that's why we're beginning with

why we're beginning with zero if you would rather begin with one

zero if you would rather begin with one we can set I to be 1 then the condition

we can set I to be 1 then the condition would be I is less than or equal to Max

would be I is less than or equal to Max let's try that again let's Loop six

let's try that again let's Loop six times 1 2 3 4 5

times 1 2 3 4 5 6 all right now we're going to create a

6 all right now we're going to create a mini

mini project we'll create a program to

project we'll create a program to simulate a

countdown perhaps we have a variable of int

int start let's start at 10 we're counting

start let's start at 10 we're counting down from

down from 10 then we'll create a for

10 then we'll create a for Loop we will set our index of I equal to

Loop we will set our index of I equal to our

our start our start variable behaves as if

start our start variable behaves as if it was the number

it was the number 10 we'll continue as long as I is

10 we'll continue as long as I is greater than zero then we will decrement

greater than zero then we will decrement by one with IUS

by one with IUS minus during each iteration let's just

minus during each iteration let's just print

print I then when we escape the the for Loop

I then when we escape the the for Loop let's print happy New

let's print happy New Year kind of like it's a countdown to a

Year kind of like it's a countdown to a new year here's what we have

currently we start at 10 count down to one then display happy New Year if you

one then display happy New Year if you would like we can use the thread class

would like we can use the thread class and have our program sleep for about 1

and have our program sleep for about 1 second between each

second between each Loop here's how you can do that after

Loop here's how you can do that after printing I this is a little Advan Java

printing I this is a little Advan Java at this level you don't need to

at this level you don't need to understand how this works but we're

understand how this works but we're going to use the thread class called The

going to use the thread class called The Sleep Method then pass in an amount of

Sleep Method then pass in an amount of milliseconds in which we would like to

milliseconds in which we would like to sleep 1,000

sleep 1,000 milliseconds now Java wants us to add

milliseconds now Java wants us to add the

the following Java wants this method of main

following Java wants this method of main to throw this exception if our thread is

to throw this exception if our thread is interrupted this is intermediate Java we

interrupted this is intermediate Java we will need the section of code in order

will need the section of code in order for our program to sleep after you

for our program to sleep after you finish this lesson be sure to remove

finish this lesson be sure to remove throws interrupted exception we'll no

throws interrupted exception we'll no longer need it print I then our program

longer need it print I then our program is going to sleep for 1 second 1,000

is going to sleep for 1 second 1,000 milliseconds all right and here's our

milliseconds all right and here's our mini

mini project 10 9 8 7 6 5 4 3 2 one Happy New

project 10 9 8 7 6 5 4 3 2 one Happy New Year

Year let's modify this program a little bit

let's modify this program a little bit now we'll use a scanner to accept user

now we'll use a scanner to accept user input scanner scanner equals new

input scanner scanner equals new scanner we have already imported the

scanner we have already imported the class with start we're going to accept

class with start we're going to accept some user

some user input but we'll need a

input but we'll need a prompt how many seconds to countown

from we will assign start to be use our scanner then use the next int method

again let's say I would like to count down from

20 and it looks like it's working I'll fast forward the video till we get to

fast forward the video till we get to the

the end 3 2

end 3 2 1 happy New

1 happy New Year so those are four Loops we can

Year so those are four Loops we can execute some code a certain amount of

execute some code a certain amount of times it's very similar to a while loop

times it's very similar to a while loop in fact there's a lot of overlap where

in fact there's a lot of overlap where you could use either a for Loop or a

you could use either a for Loop or a while loop use a for Loop if you want to

while loop use a for Loop if you want to do something a limited amount of times

do something a limited amount of times and well everybody those are four Loops

and well everybody those are four Loops in

Java I have a pretty short video for you today we're going to discuss two

today we're going to discuss two important keywords when it comes to

important keywords when it comes to Loops break and continue break is used

Loops break and continue break is used to break out of a loop continue skips

to break out of a loop continue skips the current iteration of a loop think of

the current iteration of a loop think of the break keyword as the stop button on

the break keyword as the stop button on a remote continue would be similar to

a remote continue would be similar to skip with break we're stopping with

skip with break we're stopping with continuing we're skipping let me give

continuing we're skipping let me give you a

you a demonstration let's create a for Loop

demonstration let's create a for Loop that will iterate 10 times let's say in

that will iterate 10 times let's say in I equals 0 will continue as long as I is

I equals 0 will continue as long as I is less than

less than 10 then increment I by 1 during each

10 then increment I by 1 during each iteration I'll just print I then add a

iteration I'll just print I then add a space here's what we

space here's what we got we have the numbers 0 through 9 so

got we have the numbers 0 through 9 so let's say when we reach five I would

let's say when we reach five I would like to break out of the loop we're

like to break out of the loop we're going to stop it well I could add an if

going to stop it well I could add an if statement let's

statement let's say if I is equal to 5 then we will use

say if I is equal to 5 then we will use the break keyword

the break keyword and break out of the loop

and break out of the loop entirely here's what

entirely here's what happens once we hit five we break out of

happens once we hit five we break out of the loop previously we continued all the

the loop previously we continued all the way until

way until 9 now with the continue keyword we don't

9 now with the continue keyword we don't break out of the loop we just skip the

break out of the loop we just skip the current iteration like a skip button on

current iteration like a skip button on a remote this time let's use continue

a remote this time let's use continue rather than

rather than break and we'll see the differences

break and we'll see the differences between the two

now since we're using continue the number five is missing we skipped that

number five is missing we skipped that specific cycle of the loop and went back

specific cycle of the loop and went back to the beginning that's why five is

to the beginning that's why five is missing between four and six but we

missing between four and six but we still continue to the end when working

still continue to the end when working with loops if you ever need to break out

with loops if you ever need to break out you can use the break keyword to skip

you can use the break keyword to skip the occurrent iteration you can use

the occurrent iteration you can use continue and well everybody that is both

continue and well everybody that is both the break and continue keywords in Java

the break and continue keywords in Java hello again friends today I'm going to

hello again friends today I'm going to explain nested Loops in Java a nested

explain nested Loops in Java a nested Loop is really just a loop inside of

Loop is really just a loop inside of another loop you often see nested Loops

another loop you often see nested Loops within a matrix or matrices or when we

within a matrix or matrices or when we reach the topic of data structures and

reach the topic of data structures and algorithms they might not come up for a

algorithms they might not come up for a while yeah this can be any combination

while yeah this can be any combination of for Loops or while Loops any kind of

of for Loops or while Loops any kind of loop inside of another loop let me give

loop inside of another loop let me give you a

you a demonstration let's say I would like to

demonstration let's say I would like to print the numbers 1 through N9 I can do

print the numbers 1 through N9 I can do that pretty easily with a for Loop so we

that pretty easily with a for Loop so we will create a for loop I will set an

will create a for loop I will set an index of I equal to 1 we'll continue

index of I equal to 1 we'll continue this loop as long as I is less than or

this loop as long as I is less than or equal to 9 then I will increment I by

equal to 9 then I will increment I by One during each iteration I will display

One during each iteration I will display I so this will print the

I so this will print the numbers 1- N9 or if you prefer you can

numbers 1- N9 or if you prefer you can have it all on the same l line by using

have it all on the same l line by using print instead of print line then it

print instead of print line then it would look something like

would look something like this 1 2 3 4 5 6 7 8 9 you can even

this 1 2 3 4 5 6 7 8 9 you can even separate them with the space after

separate them with the space after printing our index of I let's print a

printing our index of I let's print a space

space character and now the output looks

character and now the output looks something like

something like this what if you would like to do this

this what if you would like to do this code three times let's say print the

code three times let's say print the numbers 1 through 9 three

numbers 1 through 9 three times well you could copy and paste this

times well you could copy and paste this for

for Loop then do that two additional

Loop then do that two additional times so we have the numbers 1 through 9

times so we have the numbers 1 through 9 three

three times to put each row on a new line can

times to put each row on a new line can use an empty print line

statement then it would look something like this a

like this a matrix we seem to be repeating our code

matrix we seem to be repeating our code a lot in programming we like to follow

a lot in programming we like to follow the dry principle don't repeat yourself

the dry principle don't repeat yourself if you don't have to

if you don't have to instead why don't we create a for Loop

instead why don't we create a for Loop and stick this for Loop inside of that

and stick this for Loop inside of that Loop let's create a for Loop to iterate

Loop let's create a for Loop to iterate three times I will create an index of I

three times I will create an index of I equal to 1 we'll continue as long as I

equal to 1 we'll continue as long as I is less than or equal to three then

is less than or equal to three then increment I by One all we're going to do

increment I by One all we're going to do is take our code including the for Loop

is take our code including the for Loop and stick it within this other for Loop

and stick it within this other for Loop do pay attention to the

do pay attention to the indentation but we have we have one

indentation but we have we have one problem we're reusing this index of I

problem we're reusing this index of I you can see that Java is already giving

you can see that Java is already giving us a warning here's what

us a warning here's what happens variable I is already defined in

happens variable I is already defined in method

method main if we have a loop inside of another

main if we have a loop inside of another loop we can't use the same

loop we can't use the same index a common naming convention for a

index a common naming convention for a nested Loop is to use an index of J

nested Loop is to use an index of J rather than

rather than I because J comes next in the alphabet

I because J comes next in the alphabet after I

after I instead of printing I we're going to

instead of printing I we're going to print

print J let's see how this works and here's

J let's see how this works and here's our Matrix of data we're printing our

our Matrix of data we're printing our index of J three

times after escaping the nested for Loop we have a print line statement here if I

we have a print line statement here if I were to get rid of

were to get rid of that we'll print the numbers 1 through 9

that we'll print the numbers 1 through 9 three times all on the same

three times all on the same line let's put that back in

line let's put that back in nested Loops are really good when you're

nested Loops are really good when you're working with a matrix of data nested

working with a matrix of data nested Loops come up pretty often in the topic

Loops come up pretty often in the topic of data structures and algorithms

of data structures and algorithms because we have to Loop over sets of

because we have to Loop over sets of data now we're going to cover a mini

data now we're going to cover a mini project we're going to create a matrix

project we're going to create a matrix of a symbol that a user is going to type

of a symbol that a user is going to type in a user will set the rows and columns

in a user will set the rows and columns for this Matrix we'll declare the

for this Matrix we'll declare the following variables int

following variables int rows int

rows int columns and and Char

symbol we'll need a scanner so let's declare that we'll need a scanner

declare that we'll need a scanner scanner scanner equals new

scanner scanner equals new scanner within the set of parentheses

scanner within the set of parentheses type

type system.in let's be sure to import this

system.in let's be sure to import this class of scanner at the top of our Java

class of scanner at the top of our Java file and close the scanner when we're

file and close the scanner when we're done with it scanner.

close we're going to accept some user input a user is going to specify the

input a user is going to specify the rows the columns and the symbol we're

rows the columns and the symbol we're going to

going to use let's create some

use let's create some prompts enter the

prompts enter the number of rows I'll use print instead of

number of rows I'll use print instead of print line we will assign our variable

print line we will assign our variable of

of rows equal to use our scanner use the

rows equal to use our scanner use the next int

next int method then let's do this with columns

method then let's do this with columns enter the number of

columns columns equals scanner. nextend and the symbol we're going to

use enter the symbol to use we will assign our symbol equal to

use we will assign our symbol equal to scanner.

scanner. nextt and we can use the chart at method

give me the character at index of zero let's create a for Loop for the

zero let's create a for Loop for the columns

first let me zoom in we're going to set in

in we're going to set in I we can set it equal to

I we can set it equal to zero we'll continue as long as I is less

zero we'll continue as long as I is less than our columns whatever the user types

than our columns whatever the user types in then increment I by One

in then increment I by One during each

during each iteration I'll use print instead of

iteration I'll use print instead of print line we will print our

print line we will print our symbol let's perform a test

symbol let's perform a test run enter the rows it doesn't matter we

run enter the rows it doesn't matter we didn't set up the rows yet uh for the

didn't set up the rows yet uh for the columns let's do

columns let's do eight enter the symbol to use Let's

eight enter the symbol to use Let's do let's do a dollar sign that'd be

do let's do a dollar sign that'd be cool we have the column set set up

cool we have the column set set up currently we should have eight dollar

currently we should have eight dollar signs 1 2 3 4 5 6 7 8 we need to repeat

signs 1 2 3 4 5 6 7 8 we need to repeat this for Loop for as many rows as we

this for Loop for as many rows as we have so we're going to stick this Loop

have so we're going to stick this Loop within another

loop with our nested Loop let's replace our index of I with j

for the outer for Loop we will create a new index of I equal to zero we'll

new index of I equal to zero we'll continue this as long as I is less than

continue this as long as I is less than the rows the number of rows that a user

the rows the number of rows that a user types in then increment I by

types in then increment I by One let's perform another test

One let's perform another test run let's say I would like three rows of

run let's say I would like three rows of six and I will use an at

six and I will use an at sign so these are all on the same line

sign so these are all on the same line we should have a total of

we should have a total of 18 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

18 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 our inner loop ends after each

16 17 18 our inner loop ends after each group of six I'm going to print a new

line we can use an empty print line statement our outer for Loop is in

statement our outer for Loop is in charge of the rows our inner for Loop is

charge of the rows our inner for Loop is in charge of the columns let's see the

in charge of the columns let's see the final product I would like five

final product I would like five rows of three three

rows of three three columns I'll use an Amper sand here we

columns I'll use an Amper sand here we are we have three columns and five

rows all right everybody those are nested Loops it's really just any kind

nested Loops it's really just any kind of loop inside of another kind of loop

of loop inside of another kind of loop it doesn't matter if it's a for Loop or

it doesn't matter if it's a for Loop or a while loop we often use nested loops

a while loop we often use nested loops with matrices or when we reach the topic

with matrices or when we reach the topic of data structures and algorithms they

of data structures and algorithms they might not come up very often but you

might not come up very often but you should at least be aware of their

should at least be aware of their existence and well everybody those are

existence and well everybody those are nested Loops in

Java what is going on everybody in this video I'm going to discuss methods in

video I'm going to discuss methods in Java think of a method as a block of

Java think of a method as a block of reusable code that is executed when you

reusable code that is executed when you call it to call a method you use a set

call it to call a method you use a set of parentheses kind of like it's a pair

of parentheses kind of like it's a pair of telephones talking to each other why

of telephones talking to each other why are methods is useful well with the

are methods is useful well with the method you can write some code once and

method you can write some code once and reuse it whenever you want you just have

reuse it whenever you want you just have to call it let me show you why a method

to call it let me show you why a method is useful so let's say we have a task we

is useful so let's say we have a task we have to sing a happy birthday song three

have to sing a happy birthday song three times so without using a method we can

times so without using a method we can do something like this we'll create one

do something like this we'll create one verse of a happy birthday song I'll just

verse of a happy birthday song I'll just make something up let's

make something up let's say happy birthday to you

you you are we'll insert somebody's age here but let's say you are X years

here but let's say you are X years old then happy birthday to you

old then happy birthday to you again then I'll add a new line character

again then I'll add a new line character to the end so when we run this

to the end so when we run this code we sing Happy Birthday once if I

code we sing Happy Birthday once if I need to sing Happy Birthday let's say

need to sing Happy Birthday let's say three times well without using a method

three times well without using a method we could although it's inefficient copy

we could although it's inefficient copy this code and paste it to additional

this code and paste it to additional times then we're singing Happy Birthday

times then we're singing Happy Birthday a total of three times well you know

a total of three times well you know this does work but we tend to be

this does work but we tend to be repeating ourselves a lot in programming

repeating ourselves a lot in programming we like to follow the dry principle

we like to follow the dry principle don't repeat yourself how can we not

don't repeat yourself how can we not repeat ourselves if we don't have

repeat ourselves if we don't have to well let's create a method a method

to well let's create a method a method is just a block of reusable code so to

is just a block of reusable code so to create a method in Java outside of the

create a method in Java outside of the main method do pay attention to these

main method do pay attention to these curly braces we'll create a new method a

curly braces we'll create a new method a method can return something for now

method can return something for now we'll type void much like our main

we'll type void much like our main method and we need a name for this

method and we need a name for this method the method should be descriptive

method the method should be descriptive of what it does let's call it the happy

of what it does let's call it the happy birthday method all it does is sing

birthday method all it does is sing happy birthday we need a return type a

happy birthday we need a return type a name for the method that's descriptive

name for the method that's descriptive parentheses then curly

parentheses then curly braces let's cut our song of Happy

braces let's cut our song of Happy Birthday

Birthday birthday and paste it within the happy

birthday and paste it within the happy birthday method at any point to use this

birthday method at any point to use this method I have to call it call it by its

method I have to call it call it by its name happy birthday then add a set of

name happy birthday then add a set of parentheses so we have one issue in Java

parentheses so we have one issue in Java Java wants this method to be static much

Java wants this method to be static much like the main method that we work within

like the main method that we work within so in order for this program to

so in order for this program to work we need to add this keyword of

work we need to add this keyword of static normally you don't need this

static normally you don't need this keyword but since we're calling this

keyword but since we're calling this method of happy birthday from another

method of happy birthday from another method that's static this method also

method that's static this method also needs to be static later on in the

needs to be static later on in the series we'll discuss what static does

series we'll discuss what static does you'll likely have to include that for

you'll likely have to include that for now all right let's do a test run so we

now all right let's do a test run so we are going to sing Happy Birthday once so

are going to sing Happy Birthday once so again to call a method type the name of

again to call a method type the name of the method then a set of parentheses the

the method then a set of parentheses the pair of parentheses kind of represent a

pair of parentheses kind of represent a pair of telephones that's how I think of

pair of telephones that's how I think of it at least so now we should sing Happy

it at least so now we should sing Happy Birthday now this code is reusable we

Birthday now this code is reusable we write it once and reuse it whenever we

write it once and reuse it whenever we want we just have to call it again we

want we just have to call it again we will call the happy birthday method

again now we are executing that block of code two times or even

code two times or even three happy

birthday one thing you should be aware of is that methods are unfamiliar with

of is that methods are unfamiliar with any variables declared within other

any variables declared within other methods so let's say we have two

methods so let's say we have two variables a string of

variables a string of name type in your first name whatever it

name type in your first name whatever it is and an integer of age set it to be

is and an integer of age set it to be some

some age if I was to use these variables

age if I was to use these variables within my happy birthday method well the

within my happy birthday method well the happy birthday method actually doesn't

happy birthday method actually doesn't know what these

know what these are so let's attempt to use them and see

are so let's attempt to use them and see what happens within our happy birthday

what happens within our happy birthday song Let's convert this print statement

song Let's convert this print statement to be a print F statement and we will

to be a print F statement and we will insert our name variable replace U with

insert our name variable replace U with the format specifier and we are

the format specifier and we are displaying a string see we already have

displaying a string see we already have a warning cannot resolve symbol name

a warning cannot resolve symbol name I'll attempt to run this code and we'll

I'll attempt to run this code and we'll see what happens

see what happens exactly Java cannot find variable

exactly Java cannot find variable name methods are not familiar with

name methods are not familiar with variables inside of other methods if we

variables inside of other methods if we live in this method of main if it's our

live in this method of main if it's our house so to say

house so to say we can't see what's going on in our

we can't see what's going on in our neighbor's house one way in which we can

neighbor's house one way in which we can solve this is to pass arguments to this

solve this is to pass arguments to this method from one method we can send

method from one method we can send information to another method these are

information to another method these are known as

known as arguments so when we sing Happy Birthday

arguments so when we sing Happy Birthday within the set of parentheses within the

within the set of parentheses within the pair of telephones we can pass a value

pair of telephones we can pass a value or a variable so let's send our variable

or a variable so let's send our variable of name to this method of happy birthday

of name to this method of happy birthday anything that you send a method is known

anything that you send a method is known as an argument but we have one issue

as an argument but we have one issue though our method of happy birthday

though our method of happy birthday isn't set up to receive arguments if you

isn't set up to receive arguments if you send any values or variables to a method

send any values or variables to a method via arguments you need a matching set of

via arguments you need a matching set of what is called parameters our happy

what is called parameters our happy birthday method isn't set up to receive

birthday method isn't set up to receive these arguments we need a matching set

these arguments we need a matching set of parameters to set up some parameters

of parameters to set up some parameters we're going to list the data type of

we're going to list the data type of what we're receiving we're receiving a

what we're receiving we're receiving a string Val value so the data type is

string Val value so the data type is going to be string and then we need a

going to be string and then we need a name for what we're receiving it doesn't

name for what we're receiving it doesn't have to be exactly the same but it might

have to be exactly the same but it might be helpful to keep these consistent so

be helpful to keep these consistent so let's perform a test run after this

let's perform a test run after this print F statement I'm going to add a new

print F statement I'm going to add a new line

character happy birthday to you happy birthday dear your variable

birthday dear your variable name so if I was to change my name to

name so if I was to change my name to let's say sponge Bob we'll insert this

let's say sponge Bob we'll insert this value at this location within our

value at this location within our method happy birthday dear

method happy birthday dear SpongeBob let's also pass in our

SpongeBob let's also pass in our variable of age so any arguments you're

variable of age so any arguments you're sending to a method you're going to

sending to a method you're going to comma

comma separate however we need a matching set

separate however we need a matching set of parameters our method isn't set up to

of parameters our method isn't set up to receive this variable of age let's

receive this variable of age let's perform another test

perform another test run so we have an error actual inform

run so we have an error actual inform formal argument lists differ in length

formal argument lists differ in length we need a matching set of parameters to

we need a matching set of parameters to the arguments we're receiving not only

the arguments we're receiving not only do we need a string

do we need a string variable we need an integer variable

variable we need an integer variable because we're receiving an integer so

because we're receiving an integer so let's say int

let's say int age we'll insert our age variable right

age we'll insert our age variable right here we're displaying an integer so we

here we're displaying an integer so we need percent D this will be a print F

need percent D this will be a print F statement then I will include a new line

statement then I will include a new line character we are inserting our age

character we are inserting our age variable let's say SpongeBob is 30 years

variable let's say SpongeBob is 30 years old all right let's see how this works

old all right let's see how this works now happy birthday to you happy birthday

now happy birthday to you happy birthday dear SpongeBob you are 30 years old

dear SpongeBob you are 30 years old happy birthday to

happy birthday to you so with these parameters you can

you so with these parameters you can rename them when you receive these

rename them when you receive these arguments just be sure that the order

arguments just be sure that the order and their data type is correct for

and their data type is correct for example we could rename name as let's

example we could rename name as let's say birth day

boy you know this would work too SpongeBob is the birthday

SpongeBob is the birthday boy the names of your parameters can be

boy the names of your parameters can be different from the

arguments just be sure that you get the data type correct and the order in which

data type correct and the order in which you receive these

you receive these arguments let's replace the name of

arguments let's replace the name of SpongeBob with Patrick Patrick will be

SpongeBob with Patrick Patrick will be 38 so now now with the happy birthday

38 so now now with the happy birthday method we're inserting new variables

method we're inserting new variables happy birthday dear Patrick you are 38

happy birthday dear Patrick you are 38 years

years old with methods they also have the

old with methods they also have the capability to return a value so I'm

capability to return a value so I'm going to collapse this happy birthday

going to collapse this happy birthday method we won't be working with it

method we won't be working with it anymore let's create a method to square

anymore let's create a method to square a number we'll create a method to square

a number we'll create a method to square a number then return the result normally

a number then return the result normally if we're not returning anything we would

if we're not returning anything we would type this keyword avoid void but since

type this keyword avoid void but since we're returning a double we have to list

we're returning a double we have to list the data type of what we're returning

the data type of what we're returning we're returning a double then we need a

we're returning a double then we need a name for this method let's say double

square all we're going to do is use the return keyword let me zoom in a

return keyword let me zoom in a little let's return a number times

little let's return a number times itself number we're going to receive one

itself number we're going to receive one argument an argument of number we have

argument an argument of number we have to set up a matching parameter our

to set up a matching parameter our number is going to be a double double

number is going to be a double double number let's call the square method I

number let's call the square method I will Square the number three and again

will Square the number three and again since we're calling a method that's not

since we're calling a method that's not static from another static method we

static from another static method we need to add this keyword of static in

need to add this keyword of static in order for it to run there'll be more on

order for it to run there'll be more on the static modifier in the future so if

the static modifier in the future so if I was to run

I was to run this we get no output we're returning a

this we get no output we're returning a double back to the exact spot in which

double back to the exact spot in which we call it we could assign it to a

we call it we could assign it to a variable or print it

variable or print it directly let's say double result equals

directly let's say double result equals Square the number three then display the

Square the number three then display the result so 3^ squar would give us

result so 3^ squar would give us nine so when returning something just

nine so when returning something just imagine that after the method ends we're

imagine that after the method ends we're replacing that method call with whatever

replacing that method call with whatever we're returning in this case nine

we're returning in this case nine picture it that way and then we're

picture it that way and then we're assigning nine to our double of

assigning nine to our double of result or we can just output it directly

result or we can just output it directly if you would prefer to do it that way

if you would prefer to do it that way let's print 3^

n now let's create a method to cube we're going to return a double double

we're going to return a double double Cube we have one

Cube we have one parameter a double of

parameter a double of number we're going to return our number

number we're going to return our number time number time number that would cube

time number time number that would cube a number that we're

a number that we're given and again we need to add static

given and again we need to add static because we're calling a method from

because we're calling a method from another method that's static all right

another method that's static all right this time we will call the cube method

this time we will call the cube method and return the

and return the result so 3 cubed is 27 3 * 3 * 3 is

result so 3 cubed is 27 3 * 3 * 3 is 27 one last

27 one last example we'll create a method to return

example we'll create a method to return full name after being given a first name

full name after being given a first name and a last name we're going to return a

and a last name we're going to return a string we'll call this method get full

string we'll call this method get full name we'll have two

name we'll have two parameters a string of first for first

parameters a string of first for first name and a string of last for last name

name and a string of last for last name we're going to

we're going to return our first

return our first name plus a space to separate

name plus a space to separate them plus our last name of last

them plus our last name of last and again we have to add

and again we have to add static okay let's declare a string

static okay let's declare a string variable of full name equals call be get

variable of full name equals call be get full name method then pass in some

full name method then pass in some arguments let's pass in

arguments let's pass in SpongeBob then for the next argument

SpongeBob then for the next argument SquarePants and then we'll print the

SquarePants and then we'll print the full

full name print full name

our method returns one long string of SpongeBob

SpongeBob SquarePants the return keyword will

SquarePants the return keyword will return a value after the method ends it

return a value after the method ends it will return that value back to the place

will return that value back to the place in which you call that method after this

in which you call that method after this method of get full name is complete just

method of get full name is complete just imagine that we're replacing it with one

imagine that we're replacing it with one long string of SpongeBob

long string of SpongeBob SquarePants like this and then assigning

SquarePants like this and then assigning it to this

it to this variable okay so I lied I have one last

variable okay so I lied I have one last good example to give you will create a

good example to give you will create a method to verify a user's age normally

method to verify a user's age normally in the United States at least you have

in the United States at least you have to be 18 or older to sign up for things

to be 18 or older to sign up for things like a credit card we'll create a method

like a credit card we'll create a method to check a user's age again we're going

to check a user's age again we're going to use static because we're calling a

to use static because we're calling a method from another method that's static

method from another method that's static let me zoom in we're going to return a

let me zoom in we're going to return a Boolean this time the name of the method

Boolean this time the name of the method let's name it age

let's name it age check and there's going to be one

check and there's going to be one parameter and integer of age if we're

parameter and integer of age if we're going to do an age verification check we

going to do an age verification check we could use an if statement so within our

could use an if statement so within our method we'll write an if statement if

method we'll write an if statement if our age parameter is greater than or

our age parameter is greater than or equal to

equal to 18 then let's return

true else we're going to return false this can be simplified to the

false this can be simplified to the following

following return AG is greater than or equal to 18

return AG is greater than or equal to 18 you could do it either way for a

you could do it either way for a beginner it might be easier to read if

beginner it might be easier to read if we have separate IFL statements but both

we have separate IFL statements but both work the same all right so we now have a

work the same all right so we now have a method to check a user's

method to check a user's age so now we can use this

age so now we can use this method I will create an integer variable

method I will create an integer variable of age set it equal to some

of age set it equal to some age I'll use an if statement we're

age I'll use an if statement we're returning a Boolean value I can use that

returning a Boolean value I can use that within an if

within an if statement if H

statement if H check then pass in an argument we will

check then pass in an argument we will pass in our variable of

pass in our variable of age if this is

age if this is true if age is greater than or equal to

true if age is greater than or equal to 18 you return

18 you return true so let's print the

true so let's print the following you may sign up maybe we're

following you may sign up maybe we're signing up for a credit

signing up for a credit card else let's

card else let's print you must be 18 + 2 sign

print you must be 18 + 2 sign up our ages

up our ages 21 you may sign up but if we were

12 that method returns false you must be 18 plus to sign

18 plus to sign up so that's a method everybody it's a

up so that's a method everybody it's a block of reusable code that is executed

block of reusable code that is executed when called again I like to think of the

when called again I like to think of the parentheses after a method as a pair of

parentheses after a method as a pair of telones talking to each other to use a

telones talking to each other to use a method you have to call it and well

method you have to call it and well everybody those are methods in

Java hello everybody in this video I'm going to explain overloaded methods in

going to explain overloaded methods in Java in Java overloaded methods are

Java in Java overloaded methods are methods that share the same name but

methods that share the same name but they have different parameters a

they have different parameters a method's name plus its parameters will

method's name plus its parameters will give you a unique method signature each

give you a unique method signature each method signature needs to be unique no

method signature needs to be unique no two methods can share the same signature

two methods can share the same signature but they can share the same name let me

but they can share the same name let me give you a demonstration let's say we

give you a demonstration let's say we have a method it's going to return a

have a method it's going to return a double the method name will be add we'll

double the method name will be add we'll add two numbers together add is the

add two numbers together add is the method name and then we'll set up some

method name and then we'll set up some parameters we'll have double A for the

parameters we'll have double A for the first number and Double B all we're

first number and Double B all we're going to do is return a plus b it's a

going to do is return a plus b it's a simple

simple method so I'm I'm going to

method so I'm I'm going to print add the numbers 1 + 2 and then

print add the numbers 1 + 2 and then print

print it this will give us

it this will give us three what if I would like to add a

three what if I would like to add a third

third number you can see that Java is already

number you can see that Java is already giving us a

giving us a warning expected two arguments but three

warning expected two arguments but three found so if I were to run this program

found so if I were to run this program we get an error actual and formal

we get an error actual and formal argument lists differ in

argument lists differ in length once solution is that I could

length once solution is that I could create another method also named ad but

create another method also named ad but it has different parameters where we

it has different parameters where we accept three numbers so let me just copy

accept three numbers so let me just copy this method paste it then I'll add

this method paste it then I'll add another parameter for Double C return a

another parameter for Double C return a plus b plus C and that should

plus b plus C and that should work now the number is six these two

work now the number is six these two methods share the same name but they

methods share the same name but they have different

have different parameters so that's actually legal in

parameters so that's actually legal in Java

Java a method's name plus its parameters will

a method's name plus its parameters will give you a unique method signature no

give you a unique method signature no two methods can share the same

two methods can share the same signature with our second method let's

signature with our second method let's delete the last parameter of Double C

delete the last parameter of Double C and attempt to run this and we'll see

and attempt to run this and we'll see what happens

what happens exactly well we get an error message

exactly well we get an error message method add is already defined in class

method add is already defined in class main Java is saying that we have two

main Java is saying that we have two methods that share the same name and the

methods that share the same name and the same exact parameters methods can share

same exact parameters methods can share the same name but they need different

the same name but they need different parameters if that's the case now if I

parameters if that's the case now if I would like to add another number like

would like to add another number like four I could create another overloaded

four I could create another overloaded method also named add but this one will

method also named add but this one will have four parameters Double D return a

have four parameters Double D return a plus B+ C+

D and this works too let's go over another

too let's go over another example let's pretend that we're baking

example let's pretend that we're baking a pizza

a pizza we'll have a string variable of

we'll have a string variable of pizza we'll create a method to bake a

pizza we'll create a method to bake a pizza but we have to pass an ingredients

pizza but we have to pass an ingredients we'll declare a method with static we'll

we'll declare a method with static we'll return a string that's the return type

return a string that's the return type the method name will be Bake

the method name will be Bake Pizza our parameters are going to be a

Pizza our parameters are going to be a set of

set of ingredients for this method we'll just

ingredients for this method we'll just accept a string of

bread we'll just return our bread variable plus the word

pizza so this could be for example a thick crust pizza or a flatbread pizza

thick crust pizza or a flatbread pizza so to

so to say let's set our pizza variable equal

say let's set our pizza variable equal to called the bake pizza

to called the bake pizza method now this method only has a bread

method now this method only has a bread setup as a parameter an

setup as a parameter an ingredient let's say flat bread for the

ingredient let's say flat bread for the bread and then we'll print our

bread and then we'll print our pizza system. out. print line our string

pizza system. out. print line our string variable of

variable of pizza here's what we have we have a

pizza here's what we have we have a string of flatbread pizza so when baking

string of flatbread pizza so when baking a pizza there's a lot of different

a pizza there's a lot of different ingredients let's create another method

ingredients let's create another method of baked pizza but we have a parameter

of baked pizza but we have a parameter of bread and a parameter of cheese let's

of bread and a parameter of cheese let's copy this method paste it but we have to

copy this method paste it but we have to change the parameters we're already

change the parameters we're already receiving a warning

receiving a warning we'll have string bread and string

we'll have string bread and string cheese no pun intended let me zoom in

cheese no pun intended let me zoom in now those warnings have went away we

now those warnings have went away we have two methods with the same name but

have two methods with the same name but they have different parameters which is

they have different parameters which is fine we can do that so this time let's

fine we can do that so this time let's return a string of cheese plus a space

return a string of cheese plus a space character plus our bread plus the word

character plus our bread plus the word Pizza let's pass in a type of

Pizza let's pass in a type of cheese Mozzarella

cheese Mozzarella I probably misspelled that actually I

I probably misspelled that actually I spelled it correctly okay now we'll bake

spelled it correctly okay now we'll bake our

pizza we have a mozzarella flatbread pizza if there's two or more methods

pizza if there's two or more methods with the same name we'll end up using

with the same name we'll end up using the method where the parameters match

the method where the parameters match we'll create one more overloaded method

we'll create one more overloaded method we'll create another baked pizza method

we'll create another baked pizza method but this one will have a custom topping

but this one will have a custom topping string

string topping we'll return topping

topping we'll return topping plus a space

plus a space character plus everything we had

character plus everything we had previously then we can pass in A new

ingredient how do you spell pepperoni I can never spell

can never spell it

pepperoni now this time we have a pepperoni mozzarella flatbread

pepperoni mozzarella flatbread pizza all right everybody so those are

pizza all right everybody so those are overloaded methods methods can share the

overloaded methods methods can share the same name but they need to have a

same name but they need to have a different list of

different list of parameters a method's name plus its

parameters a method's name plus its parameters will give you a unique method

parameters will give you a unique method signature and no two methods can share

signature and no two methods can share the same signature and well everybody

the same signature and well everybody those are overloaded methods in

Java I got a relatively quick video for you today today we're going to discuss

you today today we're going to discuss variable scope in Java variable scope is

variable scope in Java variable scope is where a variable can be accessed there's

where a variable can be accessed there's two levels we'll discuss today local and

two levels we'll discuss today local and class

class we'll cover local

we'll cover local first inside of a method if you declare

first inside of a method if you declare a variable it has what is considered a

a variable it has what is considered a local scope in this demonstration let's

local scope in this demonstration let's create a variable of x x will equal some

create a variable of x x will equal some number such as one and then you know we

number such as one and then you know we can print whatever X

can print whatever X is xal

is xal 1 a variable declared inside of a method

1 a variable declared inside of a method has a local scope and I'll just add a

has a local scope and I'll just add a comment that this is a local variable

comment that this is a local variable outside of the set of curly braces where

outside of the set of curly braces where this variable is declared X isn't going

this variable is declared X isn't going to be recognized that's why if we create

to be recognized that's why if we create another method we would have to pass it

another method we would have to pass it as an

as an argument let's create another method

argument let's create another method this will be a static method that

this will be a static method that doesn't return anything I'm just going

doesn't return anything I'm just going to say it's the do something

to say it's the do something method inside of other methods you can

method inside of other methods you can declare variables that have the same

declare variables that have the same name within this other method we're

name within this other method we're going to create an integer variable of X

going to create an integer variable of X but X is going to equal two so Java

but X is going to equal two so Java isn't giving us any

isn't giving us any warnings it is legal to have variables

warnings it is legal to have variables with the same name as long as they're

with the same name as long as they're within different methods the moment I

within different methods the moment I place this variable within my main

place this variable within my main method Java is giving us a warning

method Java is giving us a warning variable X is already defined in the

variable X is already defined in the scope this local scope variable X within

scope this local scope variable X within main has a local scope variable X within

main has a local scope variable X within the do something method also has a local

the do something method also has a local scope and I'll just add a comment that

scope and I'll just add a comment that this is a local

this is a local variable if I was to print X within this

variable if I was to print X within this method and if I was to call this

method and if I was to call this method what do you think will output one

method what do you think will output one or two take a

or two take a guess

guess two within the context of our do

two within the context of our do something method xal 2 this method isn't

something method xal 2 this method isn't aware of the existence of this variable

aware of the existence of this variable within this method of main they each

within this method of main they each have a local scope it's kind of like

have a local scope it's kind of like their neighbors they can't see inside of

their neighbors they can't see inside of each other's house now a class variable

each other's house now a class variable is declared inside of a class but not

is declared inside of a class but not within any methods you usually see them

within any methods you usually see them at the top let's create a static

at the top let's create a static variable an integer of X where x equals

variable an integer of X where x equals 3 variable X within this class of main

3 variable X within this class of main has a class scope in our analogy of

has a class scope in our analogy of houses you could say that this variable

houses you could say that this variable is out in the street these two methods

is out in the street these two methods can look out their window and see

can look out their window and see variable X and that it equals

variable X and that it equals three if I was to delete these two local

three if I was to delete these two local variables and print X here's the

variables and print X here's the result xal

result xal 3 or within our main method if I was to

3 or within our main method if I was to print

print x x also equals 3 let's say that each

x x also equals 3 let's say that each method is a house they're neighbors you

method is a house they're neighbors you you could say that a class variable is

you could say that a class variable is outside they're walking down the street

outside they're walking down the street both of these methods can look outside

both of these methods can look outside their window and see this variable now

their window and see this variable now if you had a mix of both local and class

if you had a mix of both local and class variables that share the same name let's

variables that share the same name let's say int xals 1 and this was a local

say int xals 1 and this was a local variable and within our method of do

variable and within our method of do something xal

something xal two let's call the do something method

we'll print X within the main method and then within the do something

then within the do something method what do you think the output is

method what do you think the output is going to

going to be well we have one and

be well we have one and two even though there's a third X

two even though there's a third X variable within the class scope Java

variable within the class scope Java likes to use any local variables first

likes to use any local variables first if they share the same name as any class

if they share the same name as any class variables within our method of main this

variables within our method of main this method thinks xal 1 it's going to use

method thinks xal 1 it's going to use theal scope first you'll likely want to

theal scope first you'll likely want to stick with local variables over class

stick with local variables over class variables there are a few situations

variables there are a few situations when a class variable would be better

when a class variable would be better such as if you have constants where the

such as if you have constants where the value doesn't change or when working

value doesn't change or when working with object-oriented programming which

with object-oriented programming which is a whole another topic so that is

is a whole another topic so that is variable scope in Java anything with the

variable scope in Java anything with the local scope is declared inside of a

local scope is declared inside of a method or otherwise within a set of

method or otherwise within a set of curly braces and is only recognized

curly braces and is only recognized within this method other methods aren't

within this method other methods aren't aware of its existence that's sometimes

aware of its existence that's sometimes why we pass them as arguments to other

why we pass them as arguments to other methods class variables are declared

methods class variables are declared inside of a class they are recognized

inside of a class they are recognized throughout the entire class and well

throughout the entire class and well everybody that is variable scope in

Java hello everybody in this video we're going to create a very simple banking

going to create a very simple banking program using Java this video is meant

program using Java this video is meant to be a beginner's project to help us

to be a beginner's project to help us understand how methods work so if that

understand how methods work so if that sounds good to you let's get started as

sounds good to you let's get started as a beginner it might be helpful to you to

a beginner it might be helpful to you to break up your project into separate

break up your project into separate steps then tackle this project one step

steps then tackle this project one step at a time I'll add a few comments of the

at a time I'll add a few comments of the different steps our program is going to

different steps our program is going to take so first we're going to declare our

take so first we're going to declare our variables I misspelled

that then we will display a menu a user is going to pick a choice

menu a user is going to pick a choice from this menu depending on what they

from this menu depending on what they want to do they can make a deposit show

want to do they can make a deposit show their balance make a withdrawal so on

their balance make a withdrawal so on and so forth we will get and

and so forth we will get and process users

Choice we'll create a method of show balance in order to display the balance

balance in order to display the balance to the

to the user let me zoom

user let me zoom in another method to make a

in another method to make a deposit then a method to withdraw

deposit then a method to withdraw withdraw funds we'll just say

withdraw funds we'll just say withdraw and then we will create an exit

withdraw and then we will create an exit message at at the end once the user

message at at the end once the user exits so again as a beginner it might be

exits so again as a beginner it might be helpful to you to break up your program

helpful to you to break up your program into different steps we'll start with

into different steps we'll start with our step of declare variables here's the

our step of declare variables here's the different variables we'll need we have

different variables we'll need we have an account our account has a balance

an account our account has a balance such as dollars and cents so a double

such as dollars and cents so a double would make sense for the balance because

would make sense for the balance because it includes a decimal portion sents so

it includes a decimal portion sents so we have our balance we'll need a scanner

we have our balance we'll need a scanner because we're accepting us user input

because we're accepting us user input scanner scanner equals new

scanner scanner equals new scanner type system.in import this

scanner type system.in import this class import java.util.scanner and then

class import java.util.scanner and then we are going to close our scanner when

we are going to close our scanner when we're done with it let's take care of

we're done with it let's take care of that now because I'm probably going to

forget we have our scanner our balance we're going to continue this

balance we're going to continue this program as long as a user doesn't exit

program as long as a user doesn't exit we'll need a while loop we will declare

we'll need a while loop we will declare and assign a Boolean variable of is

and assign a Boolean variable of is running set that to be true continue

running set that to be true continue this program while is running is

this program while is running is true then we will accept a choice from

true then we will accept a choice from the user this will be an integer a user

the user this will be an integer a user is going to pick one to show balance two

is going to pick one to show balance two to deposit three to withdraw or four to

to deposit three to withdraw or four to exit the user is going to fill this in

exit the user is going to fill this in later using the scanner all right we

later using the scanner all right we have declared our

have declared our variables now we'll a menu to the

variables now we'll a menu to the user I will print the following let's

user I will print the following let's say banking

say banking program now you don't need to do this

program now you don't need to do this but I like to add some separators using

but I like to add some separators using a bunch of

a bunch of asterisks I just think it makes it look

cool we will lay out the different options we will have option one option

options we will have option one option one will be to show balance

withdraw four will be to exit and then I'll add another

exit and then I'll add another separator again not necessary I think it

separator again not necessary I think it would just look more organized now we

would just look more organized now we need to get and process the user's

need to get and process the user's choice

we have a variable of choice we'll need to create a

to create a prompt we will say enter your choice

prompt we will say enter your choice then hint one through

then hint one through 4 I'll use print instead of print line

4 I'll use print instead of print line because I like the user input on the

because I like the user input on the same line as the prompt we will assign

same line as the prompt we will assign our variable of choice equal to use the

our variable of choice equal to use the scanner call the next int method

scanner call the next int method ideally a user is going to type in a

ideally a user is going to type in a number 1 through 4 to do one of the

number 1 through 4 to do one of the following now we'll process the user's

following now we'll process the user's choice I think an enhanced switch would

choice I think an enhanced switch would be great for this we will create a

be great for this we will create a switch and examine our variable of

switch and examine our variable of choice we're examining our choice

choice we're examining our choice against matching cases if Choice equals

against matching cases if Choice equals a case of one we'll write an arrow to do

a case of one we'll write an arrow to do something we'll do this we're going to

something we'll do this we're going to call a method to show our B balance

call a method to show our B balance because one means the user wants to show

because one means the user wants to show their

their balance we'll fill that in later let's

balance we'll fill that in later let's write a test message I'll use

write a test message I'll use system.out.print LINE let's say show

balance case two will be for deposit we'll just print a test message

deposit we'll just print a test message of deposit again we're going to fill

of deposit again we're going to fill this method in later and call

it case three is for withdraw case

withdraw case three

withdraw case four is to exit that we can actually fill in right away it's

can actually fill in right away it's pretty

pretty simple we'll take our Boolean variable

simple we'll take our Boolean variable of is

of is running and set it to be

running and set it to be false then we'll add a default case in

false then we'll add a default case in case somebody doesn't type in a number 1

case somebody doesn't type in a number 1 through

through four we'll output

four we'll output invalid

invalid Choice Let's test numbers 1 through

Choice Let's test numbers 1 through three

three first enter a choice I'll pick one

first enter a choice I'll pick one that's for show balance again we'll be

that's for show balance again we'll be calling a method later to show our

calling a method later to show our balance two is for deposit we're

balance two is for deposit we're depositing three is for

depositing three is for withdraw four is to

withdraw four is to exit but it doesn't do anything

exit but it doesn't do anything currently

then any other choice such as five prints out invalid

five prints out invalid choice we want this program to continue

choice we want this program to continue running as long as is running remains

running as long as is running remains true so let's enclose our code within a

true so let's enclose our code within a loop a while

loop a while loop

loop while is running you don't necessarily

while is running you don't necessarily need to say equals true if it's a

need to say equals true if it's a Boolean you can just say the Boolean

Boolean you can just say the Boolean variables name name while is running is

variables name name while is running is true then do all this code so I'm going

true then do all this code so I'm going to cut our code currently and paste it

to cut our code currently and paste it within the wild

within the wild Loop now we can test is

running one is to show balance we show our balance two is to

balance we show our balance two is to deposit we

deposit we deposit three is to

deposit three is to withdraw withdraw four is to exit and we

withdraw withdraw four is to exit and we should exit processed finished with exit

should exit processed finished with exit Code Zero we know that that works

Code Zero we know that that works now our next step is to show balance and

now our next step is to show balance and this is going to be a

this is going to be a method outside of our main method we're

method outside of our main method we're going to create a new method of show

balance this has to be a static method because our main method is also

because our main method is also static there will be no return type the

static there will be no return type the return type is void the method name will

return type is void the method name will be show

be show balance there's going to be one

balance there's going to be one parameter a double of balance when we

parameter a double of balance when we call this method we have to pass in our

call this method we have to pass in our balance

balance variable within this method we're going

variable within this method we're going to use a print F

statement and I'll zoom in a little within this print F statement pick a

within this print F statement pick a unit of currency you would like to use

unit of currency you would like to use for this banking program all use

for this banking program all use American dollars we need a placeholder

American dollars we need a placeholder we'll use a percent sign and then F to

we'll use a percent sign and then F to display a double f means floating Point

display a double f means floating Point number we will display our

number we will display our balance and from the beginning I'm

balance and from the beginning I'm actually going to set my balance equal

actually going to set my balance equal to zero we're going to be testing

to zero we're going to be testing it then let me zoom out for case one

it then let me zoom out for case one we're going to call the show balance

we're going to call the show balance method but we have to pass in our

method but we have to pass in our balance variable

all right let's test it enter a choice I'll pick one to show

it enter a choice I'll pick one to show our

our balance uh here's what we got currently

balance uh here's what we got currently 0 and a bunch of zeros after the decimal

0 and a bunch of zeros after the decimal we are forgetting that new line

we are forgetting that new line character too so let's add a new line

character too so let's add a new line character to the end before I

character to the end before I forget if you would like to display two

forget if you would like to display two digits after the decimal for

digits after the decimal for example normally when you display a

example normally when you display a floating Point number using print F you

floating Point number using print F you display six digits after the decimal to

display six digits after the decimal to limit it to two we can add the

limit it to two we can add the following after our placeholder our

following after our placeholder our percent sign we're going to add

02 and to your choice I will type in one to show our balance our balance is $0

to show our balance our balance is $0 and0 we're displaying two digits after

and0 we're displaying two digits after the

the decimal let's change our initial balance

decimal let's change our initial balance to be $10 and

99 ENT to your choice I will type in one our balance is $10 and 99 I think I'm

our balance is $10 and 99 I think I'm also going to add a separator before

also going to add a separator before displaying the balance too to help with

displaying the balance too to help with readability although it's not necessary

readability although it's not necessary so I'm going to cut one of these lines

so I'm going to cut one of these lines where we display a bunch of

where we display a bunch of asterisks and print it right before

asterisks and print it right before displaying the

displaying the balance let's show our balance and

balance let's show our balance and here's our balance $10 and 99 and we

here's our balance $10 and 99 and we have some of those separators before and

have some of those separators before and after which I think looks

after which I think looks nice our show balance method is complete

nice our show balance method is complete I'm going to collapse this method we

I'm going to collapse this method we don't need to code within it

don't need to code within it anymore our next method is to make a

anymore our next method is to make a deposit we'll create a method of

deposit oh and then be sure to set your balance back to

zero we will create a static method the return type is going to be double we

return type is going to be double we will declare this method as the deposit

will declare this method as the deposit method there will be no parameters but

method there will be no parameters but we will be returning something a double

we will be returning something a double inside of this method I will create a

inside of this method I will create a local

local variable the data type is double the

variable the data type is double the name will be amount a user is going to

name will be amount a user is going to type in an amount the amount that

type in an amount the amount that they're depositing using this method

they're depositing using this method this method isn't going to work properly

this method isn't going to work properly until we return

until we return something add return statement

something add return statement just temporarily so everything runs fine

just temporarily so everything runs fine I'm just going to return zero we'll take

I'm just going to return zero we'll take care of this later I just want

care of this later I just want everything to run a compile fine we will

everything to run a compile fine we will prompt a user to type in an

prompt a user to type in an amount I will use print instead of print

amount I will use print instead of print line that's my own preference for

line that's my own preference for prompts enter an amount to be

deposited now here's one issue we're accepting user input from a user amount

accepting user input from a user amount equals if I attempt to use our scanner

equals if I attempt to use our scanner scanner. next Double there's an

scanner. next Double there's an issue our method isn't aware what the

issue our method isn't aware what the scanner is because we declared the

scanner is because we declared the scanner within a separate method our

scanner within a separate method our main method methods can't see inside of

main method methods can't see inside of each other there's a few different

each other there's a few different options one we could create a local

options one we could create a local scanner within this method you know

scanner within this method you know scanner scanner equals new scanner and

scanner scanner equals new scanner and all that I don't like the idea of

all that I don't like the idea of creating creting several different

creating creting several different scanners within this project because

scanners within this project because then we're leaving them all open to

then we're leaving them all open to accept user input so why don't we do

accept user input so why don't we do this let's take our scanner move it from

this let's take our scanner move it from this local scope and put it within a

this local scope and put it within a class scope so let's cut our scanner

class scope so let's cut our scanner within the main

within the main method and stick it within the main

method and stick it within the main class but it does need to be

class but it does need to be static because some static methods are

static because some static methods are using it this one scanner is accessible

using it this one scanner is accessible throughout the whole program now

throughout the whole program now and that warning goes away so I think

and that warning goes away so I think this would be better than creating

this would be better than creating several different scanners and leaving

several different scanners and leaving them all open throughout this program

them all open throughout this program we're just going to reuse the same one

we're just going to reuse the same one at this point we're going to verify the

at this point we're going to verify the amount that the user types

amount that the user types in I'll use an if statement first if a

in I'll use an if statement first if a user types in an amount that's negative

user types in an amount that's negative well they can't make a deposit they

well they can't make a deposit they can't deposit negative money that's

can't deposit negative money that's stupid so we will check if our amount

stupid so we will check if our amount variable that the user types in is less

variable that the user types in is less than zero if that's the case we will

than zero if that's the case we will print the

print the following amount can't be

following amount can't be negative and then we will return

zero if the user does type in an amount that's valid we'll execute an lse

that's valid we'll execute an lse statement where we're going to return

statement where we're going to return let's cut our return statement at the

let's cut our return statement at the end we'll return our amount

end we'll return our amount now when we call our method we can

now when we call our method we can delete this print line

delete this print line statement if a user selects two to make

statement if a user selects two to make a deposit we're going to assign our

a deposit we're going to assign our balance

balance variable balance equals our balance plus

variable balance equals our balance plus call the deposit

method our deposit method is going to return a number an amount if it's valid

return a number an amount if it's valid we're going to return it back to the

we're going to return it back to the place in which we call it it we will add

place in which we call it it we will add this to our current balance and reassign

this to our current balance and reassign it to balance our balance will equal our

it to balance our balance will equal our current balance plus the deposit that we

current balance plus the deposit that we make we can shorten this too we could

make we can shorten this too we could just say balance plus equals

just say balance plus equals deposit okay let's do a test

run banking program let's show our balance our balance is currently zero

balance our balance is currently zero we'll select two to make a

we'll select two to make a deposit two enter an amount to be

deposit two enter an amount to be deposited

deposited let's try and break it first let's say1

let's try and break it first let's say1 million amount can't be negative then

million amount can't be negative then we're brought back to the

we're brought back to the menu let's try and make a deposit again

menu let's try and make a deposit again enter an amount to be deposited let's

enter an amount to be deposited let's say

say $150 and a nickel 5

$150 and a nickel 5 cents that seems to have worked let's

cents that seems to have worked let's show our balance again and here's our

show our balance again and here's our New Balance $150

New Balance $150 and 5 cents all right the deposit method

and 5 cents all right the deposit method is

is done we can collapse it we no longer

done we can collapse it we no longer need to code within it and now we need a

need to code within it and now we need a withdraw

withdraw method we will declare a new

method we will declare a new method it's a static method we'll be

method it's a static method we'll be returning a

returning a double the name of this method will be

withdraw there will be one parameter we will pass in a balance double

will pass in a balance double balance we do need to return something

balance we do need to return something so temporarily just so our program runs

so temporarily just so our program runs correctly I'm just going to return zero

correctly I'm just going to return zero we'll change that

we'll change that later within this method I'm going to

later within this method I'm going to create a local variable of amount double

create a local variable of amount double amount we will prompt a

we will assign our amount equal to we're going to use our scanner and remember

going to use our scanner and remember it's within the class scope so we have

it's within the class scope so we have access to it within this method scanner.

access to it within this method scanner. nextt double to accept a

nextt double to accept a double if somebody tries to withdraw

double if somebody tries to withdraw money that they don't have we can check

money that they don't have we can check that within an if

that within an if statement if the amount is greater than

statement if the amount is greater than our balance we're passing in our balance

our balance we're passing in our balance so we know what what it is if somebody

so we know what what it is if somebody tries to withdraw a million dollars but

tries to withdraw a million dollars but they have no money in their bank account

they have no money in their bank account well they can't do

well they can't do that we will

that we will print

print insufficient

funds what if they try and withdraw negative money we can check that within

negative money we can check that within an else if

an else if statement else if our amount that the

statement else if our amount that the user types in is less than

user types in is less than zero will

zero will output amount can't be

negative else if everything checks out we'll return the amount I will cut our

we'll return the amount I will cut our current return statement we will return

current return statement we will return the amount that the user types

the amount that the user types in return

in return amount So within our if statement return

amount So within our if statement return zero within our else if statement return

zero within our else if statement return zero

zero when we reach the end we do need to

when we reach the end we do need to return something even if it is

return something even if it is zero and I'm going to use print instead

zero and I'm going to use print instead of print

of print line so let's go back to our switch

line so let's go back to our switch right here we're going to be returning a

right here we're going to be returning a double we will take our

double we will take our balance equals we're assigning it take

balance equals we're assigning it take our current balance minus call the

our current balance minus call the withdraw

withdraw method but we have to pass in our our

method but we have to pass in our our balance our original

balance our original balance from our current balance we're

balance from our current balance we're subtracting the amount that we're

subtracting the amount that we're withdrawing we can simplify this

withdrawing we can simplify this expression too we could say balance

expression too we could say balance minus equals then call the withdraw

minus equals then call the withdraw method all right let's do a test

method all right let's do a test run first we'll make a

run first we'll make a deposit I will deposit $100 to keep the

deposit I will deposit $100 to keep the simple I will show our balance we have

simple I will show our balance we have $100

$100 I will try and withdraw like a kajillion

I will try and withdraw like a kajillion dollars insufficient funds we don't have

dollars insufficient funds we don't have a kajillion

a kajillion dollar let's withdraw again I will try

dollar let's withdraw again I will try and withdraw negative money $

42069 amount can't be negative we can't withdraw negative money okay let's try

withdraw negative money okay let's try and withdraw something that's valid

$501 that seems to have worked let's show our balance our balance is now

$49.99 the last step is to exit and display a goodby

message let's print the following thank

following thank you have a nice

you have a nice day just so the user knows that they

day just so the user knows that they have exited the

have exited the program and for fun I'm going to add

program and for fun I'm going to add some text decoration some

some text decoration some separators not necessary but I think

separators not necessary but I think it'll look

nice all right let's run this one last time banking program enter your choice I

time banking program enter your choice I will show our balance we have 0 I will

will show our balance we have 0 I will make a deposit I will deposit

make a deposit I will deposit $11,000 show our balance we have

$11,000 show our balance we have $1,000 I will

$1,000 I will withdraw let's withdraw a single penny

withdraw let's withdraw a single penny 0.01 show our balance we now have

0.01 show our balance we now have $999.99

$999.99 sense I will press for to exit and we

sense I will press for to exit and we exit thank you have a nice

exit thank you have a nice day all right everybody that is a Java

day all right everybody that is a Java banking program that you can write as a

beginner hey there everybody in this video we're going to create a dice

video we're going to create a dice rolling program a user is going to type

rolling program a user is going to type in a number of dice they would like to

in a number of dice they would like to roll based on the roll of each die we

roll based on the roll of each die we will displace masy art then at the end

will displace masy art then at the end we will give the user a total the sum of

we will give the user a total the sum of all the dice that they have rolled so if

all the dice that they have rolled so if that sounds good to you let's begin as a

that sounds good to you let's begin as a beginner it might be helpful to you to

beginner it might be helpful to you to break down a large project into smaller

break down a large project into smaller steps let's list the order of steps

steps let's list the order of steps we're going to take we will Begin by

we're going to take we will Begin by declaring our

declaring our variables declare

variables declare variables then we need to get the number

variables then we need to get the number of Dice from the

of Dice from the user after we have the number of dice

user after we have the number of dice let's check to see if it's greater than

let's check to see if it's greater than zero we don't want somebody rolling

zero we don't want somebody rolling negative dice check if number of

negative dice check if number of dice is greater than

dice is greater than zero we will roll all the

dice get the total or the sum you could say the final

total or the sum you could say the final part of this project we will display the

part of this project we will display the asy art of

asy art of dice all right here's a rough outline of

dice all right here's a rough outline of our project the first step is to declare

our project the first step is to declare our

our variables we're accepting user input so

variables we're accepting user input so we'll need a scanner scanner scanner

we'll need a scanner scanner scanner equals new

equals new scanner type

scanner type system.in import this class import

system.in import this class import java.util.scanner and then close our

java.util.scanner and then close our scanner when we're done with it scanner.

scanner when we're done with it scanner. close we'll be working with random

close we'll be working with random numbers we'll need a random object to

numbers we'll need a random object to Generate random numbers random random

Generate random numbers random random equals new random

equals new random import the

import the class import java. u. random we'll need

class import java. u. random we'll need a number of dice the user is going to

a number of dice the user is going to fill this in int num of dice how many

fill this in int num of dice how many dice are we

dice are we rolling and a total int total we'll sum

rolling and a total int total we'll sum up all the dice for a

up all the dice for a total all right now we need to get the

total all right now we need to get the number of Dice from the user we'll need

number of Dice from the user we'll need some input but we'll create a prompt

some input but we'll create a prompt first enter

first enter the number of dice to

the number of dice to roll I'll use print rather than print

roll I'll use print rather than print line we will assign our variable of

line we will assign our variable of number of dice number of dice we will

number of dice number of dice we will use our scanner to accept some user

use our scanner to accept some user input we are looking for an integer

input we are looking for an integer we'll use the next int method of our

we'll use the next int method of our scanner scanner. next

scanner scanner. next in now we need to to check to see if the

in now we need to to check to see if the number of dice number of dice is greater

number of dice number of dice is greater than

than zero so let's take care of that we'll

zero so let's take care of that we'll use an if statement to check

use an if statement to check that if num of dice is greater than zero

that if num of dice is greater than zero then we'll roll some

then we'll roll some dice we'll get to that

dice we'll get to that momentarily else we will print the

following let's say number of dice must be greater than

dice must be greater than zero within our if statement let's say

zero within our if statement let's say just

just temporarily you

temporarily you roll the dice okay we're doing a test

roll the dice okay we're doing a test run enter the number of dice to roll

run enter the number of dice to roll let's say I try and roll zero dice

let's say I try and roll zero dice number of dice must be greater than zero

number of dice must be greater than zero let's try this again let's say I roll

let's try this again let's say I roll three

three Dice and then we're just printing a test

Dice and then we're just printing a test message

message you rolled the dice okay we know that

you rolled the dice okay we know that that works we can delete this print

that works we can delete this print statement we no longer need it we were

statement we no longer need it we were just testing

just testing it now we actually need to roll all the

it now we actually need to roll all the dice we'll take care of that within our

dice we'll take care of that within our if statement if the number of dice is

if statement if the number of dice is greater than zero then we will roll the

greater than zero then we will roll the dice we're going to create a for Loop

dice we're going to create a for Loop that will iterate once based on the

that will iterate once based on the number of dice we have so let's create a

number of dice we have so let's create a for

for Loop for in I will be our index in I

Loop for in I will be our index in I equals z we will continue as long as I

equals z we will continue as long as I is less than our number of

is less than our number of dice then increment our index of I by

dice then increment our index of I by One during each

One during each cycle within this for loop we're going

cycle within this for loop we're going to generate a random number I will

to generate a random number I will create a local variable of r r will

create a local variable of r r will equal now we'll use a random object to

equal now we'll use a random object to generate a random number a random number

generate a random number a random number between 1 and six we will use the next

between 1 and six we will use the next int method of our random object

int method of our random object we will specify our range 1 through 7

we will specify our range 1 through 7 the first number is inclusive the second

the first number is inclusive the second number is exclusive this will give us a

number is exclusive this will give us a random number between 1 and six

random number between 1 and six then once we have our roll let's print

then once we have our roll let's print it

it temporarily let's print you rolled colon

temporarily let's print you rolled colon space plus our local variable of Ro

let's say we would like to roll four dice you rolled five you rolled five you

dice you rolled five you rolled five you rolled one you rolled two then we'll add

rolled one you rolled two then we'll add these numbers together for a sum or

these numbers together for a sum or total let's take our

total let's take our total total equals our total plus our

total total equals our total plus our roll and this is within the for Loop so

roll and this is within the for Loop so Java does want us to initialize this

Java does want us to initialize this variable so set total equal to zero when

variable so set total equal to zero when you declare it so total equals total

you declare it so total equals total whatever it currently is in this case

whatever it currently is in this case zero plus roll we can shorten this too

zero plus roll we can shorten this too we could just say total plus equals roll

we could just say total plus equals roll we'll use the augmented assignment

we'll use the augmented assignment operator for

operator for addition then when we escape the for

addition then when we escape the for Loop we will print the

Loop we will print the total let's say total colon space plus

total let's say total colon space plus our variable of total let's do a test

our variable of total let's do a test run I Will Roll three dice we have 3 2 2

run I Will Roll three dice we have 3 2 2 for a total of seven 3 5 7 okay we know

for a total of seven 3 5 7 okay we know that that

that that works we have rolled all the dice and

works we have rolled all the dice and get the

get the total now here comes the hard part we're

total now here comes the hard part we're going to display some ASI art based on

going to display some ASI art based on the result of each die that is

the result of each die that is rolled so we're going to declare a

rolled so we're going to declare a method to take care of that for

method to take care of that for us let's do so outside of the main

us let's do so outside of the main method

method we will create a static method that's

we will create a static method that's not going to return anything the return

not going to return anything the return type is void let's name this method

type is void let's name this method print

print D D is the singular version of the word

D D is the singular version of the word dice we're going to set up one parameter

dice we're going to set up one parameter int roll what did we roll we're going to

int roll what did we roll we're going to call this method before we display the

call this method before we display the output of you rolled whatever the RO

output of you rolled whatever the RO is we will call the method of printing

is we will call the method of printing die and pass in our

die and pass in our roll it's going to be a number between 1

roll it's going to be a number between 1 and

and six let's head back to our print die

six let's head back to our print die method within the print die method we're

method within the print die method we're going to create some asky art the asky

going to create some asky art the asky art is going to be made of strings let's

art is going to be made of strings let's create a string of dice one equals now

create a string of dice one equals now instead of a standard string that takes

instead of a standard string that takes up one line we're going to create a

up one line we're going to create a multi-line string we need a triple set

multi-line string we need a triple set of double quotes

anything between these two lines is a multi-line string it's within here that

multi-line string it's within here that we're going to create some dice some asy

we're going to create some dice some asy art of dice so this will be an art

art of dice so this will be an art lesson today let's start with seven

lesson today let's start with seven dashes on the next line we'll create a

dashes on the next line we'll create a vertical bar and on the other side we

vertical bar and on the other side we need a vertical bar

need a vertical bar too I'm going to shift these dashes over

too I'm going to shift these dashes over by one same thing with the vertical bar

by one same thing with the vertical bar we need a another set of vertical

we need a another set of vertical bars another

bars another set and then we can copy our dashes

set and then we can copy our dashes again so we should have a shape like

again so we should have a shape like this right in the middle we're going to

this right in the middle we're going to add a bullet point the easiest way to do

add a bullet point the easiest way to do this is to pull up the charm map

this is to pull up the charm map application so if you hold windows and

application so if you hold windows and type R you can look up charm map hit

type R you can look up charm map hit enter if you scroll all the way down to

enter if you scroll all the way down to the bottom and up a little bit

it there should be a bullet point let's select it copy it close

point let's select it copy it close character

character map and paste that bullet point or

map and paste that bullet point or otherwise you can find it from someplace

otherwise you can find it from someplace else online let's print it just

else online let's print it just once I'm just going to print dice

once I'm just going to print dice one let's do a test run I'm just going

one let's do a test run I'm just going to roll one dice and this isn't going to

to roll one dice and this isn't going to be accurate right away

be accurate right away but we do have an asky art of a

but we do have an asky art of a one-sided

dice then we need dice two really we can copy everything for dice one paste it

copy everything for dice one paste it change dice one to dice two and move

change dice one to dice two and move this bullet point

this bullet point around so this is Dice two then we need

around so this is Dice two then we need dice

dice three dice

three dice three there will be a bullet right in

three there will be a bullet right in the middle

the middle dice

four we need the bullets in each corner and none in the center that's

corner and none in the center that's dice

dice four dice

five we'll have a bullet point right in the middle along with the corners and

the middle along with the corners and dice

six we have two rows of bullet points and those are the dice that we

and those are the dice that we need now we'll create an enhanced

switch what are we examining so going back to our

examining so going back to our parameters right here we're examining

parameters right here we're examining the role that we pass in it's going to

the role that we pass in it's going to be a number 1 through six we'll examine

be a number 1 through six we'll examine our role against matching

our role against matching cases if roll matches a case of one

cases if roll matches a case of one we'll do this

we'll do this we will print rather than print

we will print rather than print line dice

string if roll matches a case of two we will print dice

will print dice two if Case is three we will print dice

two if Case is three we will print dice three four if Case is four print dice

three four if Case is four print dice four

five print dice five and six print dice

six print dice six and a default case we might as well

six and a default case we might as well add

add one if there are no matches we'll print

one if there are no matches we'll print the

the following we'll say invalid

following we'll say invalid roll all right and that's it let's run

roll all right and that's it let's run this enter the number of dice to roll

this enter the number of dice to roll I'll roll three

I'll roll three Dice and here's what we got I rolled a

Dice and here's what we got I rolled a six a two and a

six a two and a six all right everybody so that is a

six all right everybody so that is a dice rolling program that you can make

dice rolling program that you can make using

Java what is going on everybody in this video I'm going to discuss arrays in

video I'm going to discuss arrays in Java an array is a collection of values

Java an array is a collection of values of the same data type as a beginner it

of the same data type as a beginner it might be helpful to think of an array as

might be helpful to think of an array as a variable that can store more than one

a variable that can store more than one value it's a little more complicated

value it's a little more complicated than that but that might be a good way

than that but that might be a good way to think of it let me give you a

to think of it let me give you a demonstration suppose we have a string

demonstration suppose we have a string variable a fruit pick a fruit I will

variable a fruit pick a fruit I will pick an

pick an apple and then you know we can print our

apple and then you know we can print our variable of

variable of fruit which would give me an

fruit which would give me an Apple well what if I told you that this

Apple well what if I told you that this variable can store more than one value

variable can store more than one value if we were to turn it into an array

if we were to turn it into an array here's how after the data type of our

here's how after the data type of our variable add a set of straight brackets

variable add a set of straight brackets enclose any values within a set of curly

enclose any values within a set of curly braces and there we go we now have an

braces and there we go we now have an array we have an array of

array we have an array of strings this array can store more than

strings this array can store more than one value but they all have to be the

one value but they all have to be the same data type in this case strings

same data type in this case strings let's add some more fruit let's add an

let's add some more fruit let's add an orange a

orange a banana and a coconut

banana and a coconut the name of your array should be

the name of your array should be descriptive of what it contains let's

descriptive of what it contains let's say fruits instead of

say fruits instead of fruit technically in the English

fruit technically in the English language fruit would still be plural but

language fruit would still be plural but by adding an S it's more descriptive

by adding an S it's more descriptive that it contains more than one value I

that it contains more than one value I know English is a weird language at

know English is a weird language at times if I was to print my array of

times if I was to print my array of fruits here's the

fruits here's the result while we get a memory address

result while we get a memory address arrays fall under the category of a

arrays fall under the category of a reference data type if we access the

reference data type if we access the name of our array we're given a memory

name of our array we're given a memory address each value within an array is

address each value within an array is known as an element to access an element

known as an element to access an element we have to indicate an index number

we have to indicate an index number after our array name let's add a set of

after our array name let's add a set of straight brackets and then an index

straight brackets and then an index number as is the case with many things

number as is the case with many things in programming toxis the first of

in programming toxis the first of something it usually has an index of

something it usually has an index of zero that applies to arrays as well

zero that applies to arrays as well print our array of fruits at index of

print our array of fruits at index of zero that's going to give you the first

zero that's going to give you the first element of Apple for the next element

element of Apple for the next element that would be an index of

that would be an index of one which is

one which is orange

orange two would be

two would be banana

banana three coconut if we attempt to access an

three coconut if we attempt to access an element that doesn't exist here's what

element that doesn't exist here's what happens we get an exception an exception

happens we get an exception an exception is similar to an error we have an array

is similar to an error we have an array in index out of bounds

in index out of bounds exception this error message appears

exception this error message appears when you try and access an element that

when you try and access an element that doesn't exist within an array there is

doesn't exist within an array there is no index of four there's only 0 1 2 3 in

no index of four there's only 0 1 2 3 in this case now you do have the capability

this case now you do have the capability to change the value at a given

to change the value at a given index to do so we will take the name of

index to do so we will take the name of our array in this case fruits specify an

our array in this case fruits specify an index using the set of straight brackets

index using the set of straight brackets at index of zero let's set that equal to

at index of zero let's set that equal to a string of pineapple rather than

a string of pineapple rather than Apple and then we'll print it print our

Apple and then we'll print it print our array of fruits at index of

array of fruits at index of zero that would give us a pineapple

zero that would give us a pineapple rather than an apple by specifying the

rather than an apple by specifying the index you can change any element so

index you can change any element so fruits at index of one is now a

pineapple if at any time you need the length of an array there's a built-in

length of an array there's a built-in property for that let's say say we have

property for that let's say say we have an integer variable of

an integer variable of num of fruits meaning number of

num of fruits meaning number of fruits to access the length of an array

fruits to access the length of an array take our array in this case

take our array in this case fruits use dot which is the axis

fruits use dot which is the axis modifier then type

modifier then type length give me the length of my array of

length give me the length of my array of fruits how many elements are within this

fruits how many elements are within this array take a

array take a guess four

guess four there's four elements within this array

there's four elements within this array 1 2 3 4 if you ever need the length of

1 2 3 4 if you ever need the length of an array use the length property of your

an array use the length property of your array this will return an integer which

array this will return an integer which you can assign to a variable if you

you can assign to a variable if you would like if you need to print all of

would like if you need to print all of the elements of an array you could use a

the elements of an array you could use a for Loop here's

how well declare for Loop we'll create an index of I equal to

Loop we'll create an index of I equal to zero

zero how many times do we want to iterate

how many times do we want to iterate this Loop let's continue as long as I is

this Loop let's continue as long as I is less than we need to determine the

less than we need to determine the length of this array well we can use

length of this array well we can use that length property that we discussed

that length property that we discussed take our array of fruits access the

take our array of fruits access the length property this should return the

length property this should return the number four continue as long as I is

number four continue as long as I is less than four then we will increment

less than four then we will increment our index of I so our for Loop in this

our index of I so our for Loop in this case is going to iterate four times

case is going to iterate four times let's perform a test run if I was to

let's perform a test run if I was to print my array of fruits at index of

print my array of fruits at index of zero this is what happens

zero this is what happens exactly it's going to print fruits at

exactly it's going to print fruits at index zero four times apple apple apple

index zero four times apple apple apple apple what I need is to print each

apple what I need is to print each element of this array we could use our

element of this array we could use our index V for that so replace zero with i

index V for that so replace zero with i i is going to change during each

i is going to change during each iteration of this loop we're increasing

iteration of this loop we're increasing it by one after we complete each cycle

it by one after we complete each cycle of the loop so here's what happens now

of the loop so here's what happens now we get all the elements of our array

we get all the elements of our array Apple orange banana

Apple orange banana coconut this index of I is going to

coconut this index of I is going to increase after each cycle of this Loop

increase after each cycle of this Loop each

each iteration alternatively rather than

iteration alternatively rather than printing each fruit on a new line we

printing each fruit on a new line we could use

could use print then after printing each element

print then after printing each element we could add a space

we could add a space character that would print each element

character that would print each element and separate each with a space if you so

and separate each with a space if you so choose there's something called an

choose there's something called an enhanced for Loop an enhanced for Loop

enhanced for Loop an enhanced for Loop will cycle once for each element within

will cycle once for each element within an

an array we'll start with a normal for Loop

array we'll start with a normal for Loop to create an enhanced for Loop within

to create an enhanced for Loop within the set of parentheses we will list the

the set of parentheses we will list the data type of each element of the array

data type of each element of the array in this case

in this case strings now we need a unique identifier

strings now we need a unique identifier for each element within the Sur array

for each element within the Sur array since we're working with an array of

since we're working with an array of fruits let's say fruit

fruits let's say fruit singular then we need a colon then our

singular then we need a colon then our array that we're iterating through in

array that we're iterating through in this case

this case fruits basically we're saying for every

fruits basically we're saying for every fruit in my array of fruits do

fruit in my array of fruits do this let's print each

this let's print each fruit fruit will be the current element

fruit fruit will be the current element we're cycling

we're cycling through here's what happens we print

through here's what happens we print each fruit we have all the elements of

each fruit we have all the elements of our array of fruits Apple orange banana

our array of fruits Apple orange banana coconut this is an enhanced for Loop

coconut this is an enhanced for Loop also known as a 4 each Loop it

also known as a 4 each Loop it simplifies iterating through a

simplifies iterating through a collection such as an

collection such as an array if you need to sort your array

array if you need to sort your array there's a built-in sort method we're

there's a built-in sort method we're going to access the class of arrays you

going to access the class of arrays you may need to import it import class

may need to import it import class arrays so make sure you have this import

arrays so make sure you have this import import

import java.util.arrays

java.util.arrays this class provides a lot of

this class provides a lot of functionality when working with arrays

functionality when working with arrays there's a built-in sort

there's a built-in sort method we're going to pass in our array

method we're going to pass in our array of fruits to this method we'll end up

of fruits to this method we'll end up sorting the elements in this array

alphabetically originally the order of our elements was Apple orange banana

our elements was Apple orange banana coconut but after sorting there they're

coconut but after sorting there they're now apple banana coconut orange they're

now apple banana coconut orange they're all arranged alphabetically or if these

all arranged alphabetically or if these were numbers they would be arranged in

were numbers they would be arranged in ascending

ascending order there's also a fill method with

order there's also a fill method with arrays we can fill all the elements of

arrays we can fill all the elements of an array with a given value again we're

an array with a given value again we're going to access the arrays class called

going to access the arrays class called The Fill

The Fill method pass in our array comma the value

method pass in our array comma the value we're going to fill the array with let's

we're going to fill the array with let's fill our array with pineapples

then we'll use a for each Loop to print each

each element and here's our new array we have

element and here's our new array we have filled our array of fruits with the

filled our array of fruits with the value of

value of pineapple all right everybody that's an

pineapple all right everybody that's an introduction to arrays think of an array

introduction to arrays think of an array as a variable but it can store more than

as a variable but it can store more than one value and well everybody those are

one value and well everybody those are arrays in

Java what is going on everybody in this video I'm going to show you how we can

video I'm going to show you how we can enter in user input into an array so

enter in user input into an array so let's get started before assigning

let's get started before assigning values into an array our compiler needs

values into an array our compiler needs to know the size of the array beforehand

to know the size of the array beforehand we have to first allocate space for the

we have to first allocate space for the array let's begin by creating an array

array let's begin by creating an array of strings we'll create an array of

of strings we'll create an array of strings we'll enter in some food I will

strings we'll enter in some food I will name this array Foods equals add a set

name this array Foods equals add a set of krly braces and then within this

of krly braces and then within this array you can enter in some values pick

array you can enter in some values pick some food that you like I'll enter in a

some food that you like I'll enter in a pizza

pizza taco and and

hamburger the size of this array is three

three elements once you set a size for an

elements once you set a size for an array normally you can't change it this

array normally you can't change it this array will have three elements however

array will have three elements however all the elements are already filled with

all the elements are already filled with values to create an empty array you

values to create an empty array you don't want a set of empty curly braces

don't want a set of empty curly braces then we're creating an array of no

then we're creating an array of no elements just to demonstrate that I'm

elements just to demonstrate that I'm going to print the length of our array

going to print the length of our array Foods foods. length

Foods foods. length this is going to give us

this is going to give us zero and we can't assign any values even

zero and we can't assign any values even if I attempt to let's say Foods at index

if I attempt to let's say Foods at index zero equals a string of pizza here's

zero equals a string of pizza here's what

happens well we have an exception and array index out of bounds exception

array index out of bounds exception before assigning values we'll want to be

before assigning values we'll want to be sure that we're setting a size of the

sure that we're setting a size of the array even if it is empty instead of

array even if it is empty instead of assigning a set of values we'll create

assigning a set of values we'll create an empty array we'll set our array equal

an empty array we'll set our array equal to use the new keyword type the data

to use the new keyword type the data type of our array straight brackets and

type of our array straight brackets and within the straight brackets we'll set a

within the straight brackets we'll set a size a number so let's say three we're

size a number so let's say three we're creating an empty array that has space

creating an empty array that has space for three elements three values let's

for three elements three values let's try this

try this again the length of our array is three

again the length of our array is three and we can assign the values so let's

and we can assign the values so let's say Foods at index

say Foods at index one equals a

one equals a taco Foods at index 2 will be a

hamburger I'll print all the foods in this array we can use an enhanced for

this array we can use an enhanced for Loop list the data type we're working

Loop list the data type we're working with an array of strings for every food

with an array of strings for every food in our array of

in our array of foods we will print each

foods we will print each food that would give us pizza Taco

food that would give us pizza Taco hamburger we have declared and

hamburger we have declared and instantiated an empty array and filled

instantiated an empty array and filled in the values

in the values later let's modify this program so a

later let's modify this program so a user can type in some values let's

user can type in some values let's delete these lines if we're accepting

delete these lines if we're accepting user input we will need a scanner we'll

user input we will need a scanner we'll declare that and instantiate it scanner

declare that and instantiate it scanner scanner equals new

scanner equals new scanner within the set of parentheses

scanner within the set of parentheses typ

typ system.in import the class for

system.in import the class for scanner import java.util.scanner and

scanner import java.util.scanner and close the scanner when you're done

close the scanner when you're done because I sometimes forget to do that

because I sometimes forget to do that still scanner.

still scanner. close so we have an empty array of three

close so we have an empty array of three elements we'll create a for Loop to

elements we'll create a for Loop to iterate over the length of our array of

iterate over the length of our array of foods so four we'll create a counter of

foods so four we'll create a counter of in I equals z will continue as long as I

in I equals z will continue as long as I is less

is less than our array of foods length property

than our array of foods length property which returns three because there's

which returns three because there's three elements then increment I by One

three elements then increment I by One during each iteration of this Loop let's

during each iteration of this Loop let's do the

do the following we'll output the following

following we'll output the following prompt enter a

prompt enter a food I'll use print instead of print

food I'll use print instead of print line because I prefer

line because I prefer that we'll assign our array of foods at

that we'll assign our array of foods at index of I I changes during each cycle

index of I I changes during each cycle at first it's zero then 1 then two then

at first it's zero then 1 then two then three we'll set that equal to use our

three we'll set that equal to use our scanner to accept some user input call

scanner to accept some user input call the next line

the next line method okay let's perform a test run

method okay let's perform a test run currently we have an array with three

currently we have an array with three empty elements we'll cycle this loop

empty elements we'll cycle this loop three times because the length property

three times because the length property of the array is three then print all the

of the array is three then print all the elements when we're done

elements when we're done here's what happens exactly enter a food

here's what happens exactly enter a food pizza Taco

pizza Taco hamburger here are the elements within

hamburger here are the elements within our array of food pizza Taco

our array of food pizza Taco hamburger let's say that we change the

hamburger let's say that we change the size of the array let's say for this

size of the array let's say for this time Pizza Taco

time Pizza Taco hamburger hot

hamburger hot dog Pizza Taco hamburger hot dog

dog Pizza Taco hamburger hot dog we're going to make a few changes

we're going to make a few changes instead of setting a static size for the

instead of setting a static size for the array we'll have a user enter in the

array we'll have a user enter in the number of food they would like to enter

number of food they would like to enter we'll replace this number with a

we'll replace this number with a variable to determine the size what

variable to determine the size what we'll do now is we will declare our

we'll do now is we will declare our string array of foods but instantiate it

string array of foods but instantiate it later once we know the

later once we know the size we'll

size we'll output what number of food do you want

I'll use print instead of print line I'll also create an integer

line I'll also create an integer variable of size I'll declare it but not

variable of size I'll declare it but not yet fill it in until after our

yet fill it in until after our prompt let's set the size the size of

prompt let's set the size the size of the array that is equal to use our

the array that is equal to use our scanner and call the next int method we

scanner and call the next int method we are accepting an

are accepting an integer once we know the size of the

integer once we know the size of the array we can finish instantiating it

array we can finish instantiating it let's take our array of foods that we've

let's take our array of foods that we've declared but have not yet assigned and

declared but have not yet assigned and we'll assign it our array is made up of

we'll assign it our array is made up of strings we'll use the new keyword new

strings we'll use the new keyword new list the data type

list the data type string it's an array so we need a set of

string it's an array so we need a set of straight

straight brackets and instead of a number we're

brackets and instead of a number we're going to use our variable the user is

going to use our variable the user is going to determine what this number is

going to determine what this number is going to

going to be there's one final step this is

be there's one final step this is specific for scanners since we're

specific for scanners since we're accepting an integer and then we're

accepting an integer and then we're accepting a string for our user input we

accepting a string for our user input we have to clear the input buffer next

have to clear the input buffer next integer isn't going to pick up the new

integer isn't going to pick up the new line character at the end so just to

line character at the end so just to demonstrate

demonstrate that let's say we want one food

that let's say we want one food item there's still that new line

item there's still that new line character within the input buffer we

character within the input buffer we didn't get the opportunity to enter in a

didn't get the opportunity to enter in a food we are just going to clear our

food we are just going to clear our scanner by using scanner. next line and

scanner by using scanner. next line and that will clear it

that will clear it up all right let's try this again

what number of food do you want I want five five food items enter in some food

five five food items enter in some food pizza

pizza Taco

Taco hamburger hot dog and

hamburger hot dog and Sushi and here's our food pizza Taco

Sushi and here's our food pizza Taco hamburger hot dog

hamburger hot dog sushi in summary to enter values into an

sushi in summary to enter values into an array you'll likely want to create an

array you'll likely want to create an empty array but you need to know the

empty array but you need to know the size of the array first

size of the array first if the size of the array is

if the size of the array is predetermined you can always set that to

predetermined you can always set that to be a number otherwise if one way or

be a number otherwise if one way or another if a user is going to determine

another if a user is going to determine the size of the array you'll have to get

the size of the array you'll have to get that from the user and you can set the

that from the user and you can set the size of the array to whatever the user

size of the array to whatever the user types in just be sure to do that before

types in just be sure to do that before filling in the values if you would like

filling in the values if you would like a copy of this code you can look in the

a copy of this code you can look in the comment section down below be sure that

comment section down below be sure that you're looking in the playlist and well

you're looking in the playlist and well everybody that is how to enter and user

everybody that is how to enter and user data into an array using

Java what is is going on everybody in this video I'm going to show you how we

this video I'm going to show you how we can search through the elements of an

can search through the elements of an array let's begin we'll need an array to

array let's begin we'll need an array to work with to keep the simple let's

work with to keep the simple let's create an array of integers we'll create

create an array of integers we'll create an array of integers named numbers

an array of integers named numbers equals make up some numbers to put

equals make up some numbers to put within this array I'll just type

within this array I'll just type whatever comes to

mind good enough we'll also need a Target what number are we searching for

Target what number are we searching for let's say I'm searching for the number

let's say I'm searching for the number number two I will create an integer

number two I will create an integer variable of Target set it equal to

variable of Target set it equal to two in data structures and algorithms

two in data structures and algorithms we'll be performing what is known as a

we'll be performing what is known as a linear search we're going to use a for

linear search we're going to use a for Loop to iterate through these elements

Loop to iterate through these elements and then see if there's a match we'll

and then see if there's a match we'll create a for Loop create an index of I I

create a for Loop create an index of I I will equal zero we'll continue as long

will equal zero we'll continue as long as I is less than R array of numbers

as I is less than R array of numbers access the length property that will

access the length property that will return the length as a number then

return the length as a number then increment I by

increment I by One I will check using an if

One I will check using an if statement if our

statement if our Target is

Target is equal to our array at the current index

equal to our array at the current index of I at first I will be zero and then we

of I at first I will be zero and then we increment it during each cycle of this

increment it during each cycle of this Loop if our Target equals the current

Loop if our Target equals the current element let's print the following

let's say element found at index plus I that's our

index plus I that's our index in case we find the target for

index in case we find the target for example two we don't need to search

example two we don't need to search through the rest of the array we could

through the rest of the array we could add what is known as a break statement

add what is known as a break statement to break out of the

to break out of the loop if we find the target break out of

loop if we find the target break out of the loop let's perform a test run we're

the loop let's perform a test run we're searching for the number two

searching for the number two and we'll be given the index element

and we'll be given the index element found at index

found at index 2 let's look for

2 let's look for one one is found at index

one one is found at index zero four which is near the end is found

zero four which is near the end is found at index 6 0 1 2 3 4 5 6 what if we

at index 6 0 1 2 3 4 5 6 what if we don't find our Target I don't have the

don't find our Target I don't have the number seven in

here well there's no output since this if statement is never true

since this if statement is never true once we reach the end of the array we

once we reach the end of the array we don't do anything so let's add a Boolean

don't do anything so let's add a Boolean variable of is

variable of is found and set it to be

found and set it to be false we'll check if is found is false

false we'll check if is found is false if that is the case we'll output a

if that is the case we'll output a message that element wasn't found in the

message that element wasn't found in the array so if we do find our Target we'll

array so if we do find our Target we'll take our Boolean variable of is found

take our Boolean variable of is found and set it to be true we have found our

and set it to be true we have found our Target that we're looking

for if we exit the for Loop and never find our Target we can check

find our Target we can check that we'll say is

that we'll say is found but we'll use the not logical

found but we'll use the not logical operator the not logical operator gives

operator the not logical operator gives you the inverse of a Boolean value or

you the inverse of a Boolean value or variable if is found is false if

variable if is found is false if something isn't true if we don't find

something isn't true if we don't find the target then we execute this if

the target then we execute this if statement where we will print the

statement where we will print the following let's say something such as

following let's say something such as element not found in the

element not found in the array all right we are looking for the

array all right we are looking for the number seven which does not exist within

number seven which does not exist within this

this array that would give us this message

array that would give us this message element not found in the array because

element not found in the array because is found was false we could never find

is found was false we could never find it within this for

it within this for Loop so we're checking if is found is

Loop so we're checking if is found is not

not true what if we have an array of strings

true what if we have an array of strings and we're searching for an element well

and we're searching for an element well instead of using the comparison operator

instead of using the comparison operator we have to use the equals method of

we have to use the equals method of strings because strings are a reference

strings because strings are a reference data type so this time let's say we have

data type so this time let's say we have an array of

an array of strings named fruits think of some

strings named fruits think of some fruit I will pick an apple

fruit I will pick an apple an

an orange and a

orange and a banana the target this time will be a

orange will iterate through our array of fruits the condition for the for Loop

fruits the condition for the for Loop will be I is less than the length of our

will be I is less than the length of our array of fruits now we can't necessarily

array of fruits now we can't necessarily say is our Target equal to

say is our Target equal to fruits at index of

fruits at index of I we're comparing two strings and since

I we're comparing two strings and since strings are reference data types we

strings are reference data types we would end up comparing the memory

would end up comparing the memory addresses of two different strings we

addresses of two different strings we would be saying are these two memory

would be saying are these two memory addresses the same are they at the same

addresses the same are they at the same location which isn't the case if we're

location which isn't the case if we're comparing the value of strings we'll use

comparing the value of strings we'll use the equals

the equals method let's take fruits at index of I

method let's take fruits at index of I call the built-in equals method of

call the built-in equals method of strings and pass in our Target as an

strings and pass in our Target as an argument now this should work we are

argument now this should work we are searching for an

orange element found at index one what about a

pineapple element not found in the array there was no pineapple let's modify this

there was no pineapple let's modify this program slightly we'll accept some user

program slightly we'll accept some user input but we'll need a scanner

import the class java.util.scanner and close your

class java.util.scanner and close your scanner when you're done with it

scanner when you're done with it scanner.

scanner. close instead of assigning our Target

close instead of assigning our Target we'll accept user input we'll use our

we'll accept user input we'll use our scanner use the next line

scanner use the next line method and we will also need a

method and we will also need a prompt let's print the following

prompt let's print the following enter a fruit to search

for just to make this a little more clean I'm going to move this variable of

clean I'm going to move this variable of is found to the top

is found to the top here I'll declare our string of Target

here I'll declare our string of Target but not assign it and then after the

but not assign it and then after the prompt I'll assign our name of Target

prompt I'll assign our name of Target this is just how I like to arrange

this is just how I like to arrange things but it all works the same now we

things but it all works the same now we can search for an element after acting

can search for an element after acting user input and I will convert this to be

user input and I will convert this to be a print statement instead of print line

a print statement instead of print line all right let's search for some fruit is

all right let's search for some fruit is there a coconut element not found in the

array perhaps a banana element found at index 2 0 1 2 all right everybody so

index 2 0 1 2 all right everybody so that's how to search through an array

that's how to search through an array using

Java hello everybody in this video I'm going to explain variable arguments also

going to explain variable arguments also known as VAR args in Java variable

known as VAR args in Java variable arguments allow a method to accept a

arguments allow a method to accept a varying number of arguments they make

varying number of arguments they make methods more flexible and there's no

methods more flexible and there's no need for overloaded methods overloaded

need for overloaded methods overloaded methods are methods that share the same

methods are methods that share the same name but have different

name but have different parameters in this example I have

parameters in this example I have several add methods they each have

several add methods they each have different amounts of parameters if I was

different amounts of parameters if I was to add a few numbers together for

to add a few numbers together for example I'll add 1 + 2 + 3 well then I

example I'll add 1 + 2 + 3 well then I would use this method what if I told you

would use this method what if I told you instead of creating several different

instead of creating several different methods that basically do the same thing

methods that basically do the same thing we could instead create one method that

we could instead create one method that accepts any number of

accepts any number of arguments we'll only need to declare one

arguments we'll only need to declare one method we will create one add method

method we will create one add method that accepts a varying amount of

that accepts a varying amount of arguments so let's create a method the

arguments so let's create a method the return type let's say is an integer

return type let's say is an integer we'll create a method of add our method

we'll create a method of add our method will have one parameter what is the data

will have one parameter what is the data type of the values we're sending this

type of the values we're sending this method in this case

method in this case integers we're going to follow the data

integers we're going to follow the data type with three dots and

type with three dots and ellipses how this works is that the Java

ellipses how this works is that the Java compiler is going to pack the arguments

compiler is going to pack the arguments we send it into an array we'll need a

we send it into an array we'll need a name for this array let's say

name for this array let's say numbers just to demonstrate this

numbers just to demonstrate this temporarily I'm going to print my array

temporarily I'm going to print my array of

numbers when we call the add method we can send any number of arguments for

can send any number of arguments for example 1 2 3 4 and they're going to be

example 1 2 3 4 and they're going to be packed into an

packed into an array within this method we're now

array within this method we're now working with an array let's perform a

working with an array let's perform a test

test run let's return void

actually so we're given a memory address of this array now let's actually add

of this array now let's actually add these numbers

these numbers together we need to cycle through the

together we need to cycle through the elements of this array we can use a for

elements of this array we can use a for Loop or an enhanced for Loop for that so

Loop or an enhanced for Loop for that so let's return an integer in this

let's return an integer in this case let's declare a local variable of

case let's declare a local variable of sum I will set that to be

zero let's create an enhanced for Loop the data type will be int for every

Loop the data type will be int for every number in my array of numbers

number in my array of numbers let's take our sum and add the current

let's take our sum and add the current number sum plus equals

number sum plus equals number then at the end we will return

number then at the end we will return our

our sum and there we go and then we need to

sum and there we go and then we need to print the output I'm going to cut this

print the output I'm going to cut this and paste it within a print

and paste it within a print statement let's perform a test run the

statement let's perform a test run the sum when we add these four numbers

sum when we add these four numbers together the sum is 10 and we can pass

together the sum is 10 and we can pass in any number of

arguments the result is now 21 basically the Java compiler is

21 basically the Java compiler is packing all of these arguments into an

packing all of these arguments into an array when we send them to a method then

array when we send them to a method then within the context of this method we

within the context of this method we would just need to work with this array

would just need to work with this array one way or another but it's a lot easier

one way or another but it's a lot easier than having several different overloaded

than having several different overloaded methods okay this time let's create a

methods okay this time let's create a new method we'll create a method of

new method we'll create a method of average average will find the average

average average will find the average value of whatever we send it so we will

value of whatever we send it so we will create a static method that's going to

create a static method that's going to return a double this time the method

return a double this time the method name will be

name will be average what is the data type of what

average what is the data type of what we're sending let's say double then we

we're sending let's say double then we need the ellipses the three dots then a

need the ellipses the three dots then a unique name for this array let's say

unique name for this array let's say numbers so to find the average we can

numbers so to find the average we can perform the following

perform the following code let's say we have

code let's say we have double sum

double sum I will set that equal to

I will set that equal to zero we will create an enhanced for Loop

zero we will create an enhanced for Loop the data type is double for every number

the data type is double for every number in my array of numbers do the following

in my array of numbers do the following we will take our

we will take our sum and add the current number sum plus

sum and add the current number sum plus equals

equals number then at the end we will return

number then at the end we will return sum divided by now since we're working

sum divided by now since we're working with an array there is a built-in length

with an array there is a built-in length property numbers. length to find the

property numbers. length to find the average you take all the numbers add

average you take all the numbers add them together then divide it by the

them together then divide it by the amount of numbers that you

amount of numbers that you have let's perform a test

have let's perform a test run I'm going to

run I'm going to print call the average

print call the average method let's find the average of a few

method let's find the average of a few numbers I don't know what that's going

numbers I don't know what that's going to be so the average of these four

to be so the average of these four numbers is 2.5

numbers is 2.5 I can pass in any number of

I can pass in any number of arguments so the average of these

arguments so the average of these numbers is four

numbers is four 4.0 you can even pass in no arguments if

4.0 you can even pass in no arguments if you so

you so choose but with this method that we have

choose but with this method that we have created here's what

created here's what happens we're actually dividing by zero

happens we're actually dividing by zero because the length of our array is zero

because the length of our array is zero there's no elements that we're passing

there's no elements that we're passing in in this specific example let's create

in in this specific example let's create an if

an if statement if our array of

statement if our array of numbers if the length of it we can

numbers if the length of it we can access the length property is equal to

access the length property is equal to zero let's return zero instead of

zero let's return zero instead of receiving noted number we're calling the

receiving noted number we're calling the average method but passing in no

average method but passing in no arguments this

arguments this time that would give us zero because the

time that would give us zero because the length of our array is zero because

length of our array is zero because we're passing in no arguments I already

we're passing in no arguments I already everybody so those are variable

everybody so those are variable arguments they allow a method to accept

arguments they allow a method to accept a varying number of arguments it makes

a varying number of arguments it makes methods more flexible and there's no

methods more flexible and there's no need for overloaded methods the Java

need for overloaded methods the Java compiler will pack the arguments into an

compiler will pack the arguments into an array when setting up the parameters of

array when setting up the parameters of a method declare the data type and add a

a method declare the data type and add a suffix of an ellipsis Three Dots and

suffix of an ellipsis Three Dots and well everybody those are variable

well everybody those are variable arguments in

Java hey there everybody so today I'm going to explain 2D arrays in Java also

going to explain 2D arrays in Java also known as multi-dimensional arrays a

known as multi-dimensional arrays a two-dimensional array is an array where

two-dimensional array is an array where each element is an array it's useful for

each element is an array it's useful for storing a matrix of data let me give you

storing a matrix of data let me give you an example let's say we have some basic

an example let's say we have some basic one-dimensional arrays I will create a

one-dimensional arrays I will create a string array of

string array of fruits think of some

fruits think of some fruit I'll add an

fruit I'll add an apple an orange and a

apple an orange and a banana then I'll create another separate

banana then I'll create another separate array let's create a string array of

array let's create a string array of vegetables think of some

vegetables think of some vegetables I will add a

vegetables I will add a potato an

potato an onion and a

onion and a carrot let's create one more I will

carrot let's create one more I will create a string array of

create a string array of meats I will add

meats I will add chicken pork

fish these three arrays are all separate one-dimensional arrays well what if I

one-dimensional arrays well what if I told you we can make an array made of

told you we can make an array made of arrays where each element is an array

arrays where each element is an array here's how we're going to combine all

here's how we're going to combine all these arrays together into a grid or

these arrays together into a grid or Matrix I will create a two-dimensional

Matrix I will create a two-dimensional array of strings we will need two sets

array of strings we will need two sets of straight brackets I will name this

of straight brackets I will name this two-dimensional array

groceries and then we need our curly braces this two-dimensional array each

braces this two-dimensional array each element within this two-dimensional

element within this two-dimensional array is going to be an array we have

array is going to be an array we have fruits

fruits vegetables and

meats let's attempt to display these elements you can use a for Loop or an

elements you can use a for Loop or an enhanced for Loop

enhanced for Loop within this for Loop what is the data

within this for Loop what is the data type of each element well each element

type of each element well each element is a string

is a string array so we need to list the data type

array so we need to list the data type as a string array let's give a nickname

as a string array let's give a nickname of each element as

of each element as Foods in our two-dimensional array of

Foods in our two-dimensional array of groceries let me show you what happens

groceries let me show you what happens if I print each element within our

if I print each element within our two-dimensional array of

two-dimensional array of groceries I will print each array of

groceries I will print each array of foods here's what we got

foods here's what we got well we get a bunch of memory addresses

well we get a bunch of memory addresses because arrays are a reference data type

because arrays are a reference data type we're referring to some place in

we're referring to some place in memory we'll need to use a nested

Loop an enhanced for Loop would be good for this with each of these arrays what

for this with each of these arrays what is the data type of each element within

is the data type of each element within each well we're working with strings so

each well we're working with strings so the data type is going to be string

the data type is going to be string let's give a nickname of each element as

let's give a nickname of each element as food

food in our array of

in our array of foods during each cycle of this Loop

foods during each cycle of this Loop let's print not print line each food and

let's print not print line each food and then I'll add a

currently we have our first array and our second then

our second then third after finishing each array I'm

third after finishing each array I'm going to add a new line

going to add a new line character we can use a print line

character we can use a print line statement for that

here's what we got now what we have is a grid or Matrix of data you can say that

grid or Matrix of data you can say that there's

there's columns and

array now when initializing an array you don't necessarily needed names let's

don't necessarily needed names let's remove

remove fruits copy the elements of this array

fruits copy the elements of this array including the curly braces and paste

including the curly braces and paste them within this two-dimensional array

them within this two-dimensional array just for readability I'm going to place

just for readability I'm going to place each row on a new

line let's replace vegetables with the elements including the curly

elements including the curly braces same thing applies with

meats and we can delete all this this would work the

this this would work the same groceries is a matrix of data a gri

same groceries is a matrix of data a gri let's print

let's print this and that works the

this and that works the same if you ever need to access or

same if you ever need to access or change an element you'll need to use two

change an element you'll need to use two indices for example let's replace apple

indices for example let's replace apple with the pineapple we will take our

with the pineapple we will take our two-dimensional array of groceries and

two-dimensional array of groceries and list two

list two indices the first index applies to the

indices the first index applies to the row the second index applies to the

row the second index applies to the column so we're saying at row 0 column

column so we're saying at row 0 column 0 we can change it or access it let's

0 we can change it or access it let's say that row 0 column 0 is now a

say that row 0 column 0 is now a pineapple rather than an apple then we

pineapple rather than an apple then we have pineapple orange

have pineapple orange banana let's replace our potato with

banana let's replace our potato with something

something else that would be Row one column 0 Row

else that would be Row one column 0 Row one column 0 is now

carrot let's replace the carrot with celery then that would be Row one column

celery then that would be Row one column 2 0 1 2 Row one column

2 0 1 2 Row one column 2 potato onion

2 potato onion celery let's replace pork with eggs that

celery let's replace pork with eggs that would be row two 0 1 2 column 1 0 1

would be row two 0 1 2 column 1 0 1 row two column one is now

eggs we have chicken eggs beef fish to access or modify an element

fish to access or modify an element within a 2d array you need to list two

within a 2d array you need to list two indices the first for the row the second

indices the first for the row the second for the

for the column okay now we're going to create a

column okay now we're going to create a mini

mini project we'll create a two-dimensional

project we'll create a two-dimensional array that resembles a telephone number

array that resembles a telephone number pad this two-dimensional array will be

pad this two-dimensional array will be made up of characters

made up of characters the data type is Char and then we have

the data type is Char and then we have two sets of straight brackets let's name

two sets of straight brackets let's name this two-dimensional array telephone

this two-dimensional array telephone equals we have an array of arrays we'll

equals we have an array of arrays we'll have four

rows and just for readability I'm going to place each of these on a new

to place each of these on a new line just so it resembles a grid or

line just so it resembles a grid or Matrix for the first row we'll have one

two three and these are all characters not strings we're using single quotes

not strings we're using single quotes not double quotes for the second row

not double quotes for the second row we'll have

we'll have four

four 5

5 6 the third row will be

6 the third row will be 7

7 8

8 9 now for the last row we'll have an

9 now for the last row we'll have an asterisk

asterisk character Zero

and pound or hashtag as I like to call it so here's our Matrix our grid of

it so here's our Matrix our grid of characters we have an array of arrays it

characters we have an array of arrays it has rows and

columns now let's display our data we'll need nested Loops for

this our outer for Loop is going to be in charge of the rows what is the data

in charge of the rows what is the data type of each element within this

type of each element within this two-dimensional array well each row is

two-dimensional array well each row is an array of characters that's going to

an array of characters that's going to be the data type of the outer for Loop

be the data type of the outer for Loop we have an array of characters let's

we have an array of characters let's give a nickname of each inner array as a

give a nickname of each inner array as a row in our two-dimensional array of

row in our two-dimensional array of telephone for every Row in our telephone

telephone for every Row in our telephone do this then we'll need a nested

do this then we'll need a nested Loop what is the data type of each

Loop what is the data type of each element within each array their

element within each array their characters the data type will be

characters the data type will be Char let's say for every number

Char let's say for every number in each array of row we'll print the

in each array of row we'll print the following we'll use print rather than

following we'll use print rather than print

print line we'll print each number and I'll

line we'll print each number and I'll add a space

add a space character let's do a test

character let's do a test run after each row I'm going to print a

run after each row I'm going to print a new line character

new line character so when we escape the inner four Loop

so when we escape the inner four Loop I'll add an empty print line

I'll add an empty print line statement and here's our telephone we

statement and here's our telephone we have

have rows and

rows and columns it's a two-dimensional array of

columns it's a two-dimensional array of characters so those are two-dimensional

characters so those are two-dimensional arrays they're an array where each

arrays they're an array where each element is an array it's useful for

element is an array it's useful for storing a matrix of data we probably

storing a matrix of data we probably won't be using 2D arrays too often but

won't be using 2D arrays too often but you should still be familiar with them

you should still be familiar with them and well everybody those are two

and well everybody those are two dimensional arrays in

Java hello everybody in this video we're going to create an interactive quiz game

going to create an interactive quiz game using Java for this project you'll

using Java for this project you'll create an array of your own custom

create an array of your own custom questions and a two-dimensional array of

questions and a two-dimensional array of all the different options for answers

all the different options for answers that we have you'll type in a number 1

that we have you'll type in a number 1 through four depending on your guess

through four depending on your guess after all of the questions are answered

after all of the questions are answered we will display a final score depending

we will display a final score depending on the amount of correct guesses that

on the amount of correct guesses that you have so let's begin as a beginner it

you have so let's begin as a beginner it might be helpful to you to break down

might be helpful to you to break down your project into different steps as

your project into different steps as comments we'll list all of the different

comments we'll list all of the different steps we need to take to get this

steps we need to take to get this program up and running the first thing

program up and running the first thing that we need is an array of questions

that we need is an array of questions questions will be an

questions will be an array we will also need

array we will also need options options will be a

options options will be a two-dimensional

two-dimensional array we will declare our

array we will declare our variables we'll need a welcome message

we will list each question using a loop I'll just write in parenthesis that

loop I'll just write in parenthesis that we will use a loop now within this loop

we will use a loop now within this loop we're going to do a few things we will

we're going to do a few things we will list our

list our options then get guess from

options then get guess from user then check our guess to see if it's

user then check our guess to see if it's correct at the end of this program we

correct at the end of this program we will display find fin

score so here's a rough outline of our project we'll fill this project in one

project we'll fill this project in one step at a time let's begin with creating

step at a time let's begin with creating an array of questions we'll ask the

an array of questions we'll ask the user the data type will be a string

user the data type will be a string array of

questions here's where you're going to ask all of your questions in this

ask all of your questions in this project we'll have five

project we'll have five questions they're all going to be very

questions they're all going to be very long strings

for our first question you don't need to type in the same questions that I do

type in the same questions that I do feel free to come up with your own

feel free to come up with your own here's a few that I've looked up online

here's a few that I've looked up online my first question will be what is the

my first question will be what is the main function of a

main function of a router that'll be the first question

router that'll be the first question I'll put each of these questions on a

I'll put each of these questions on a new line just for

new line just for readability the second question will be

readability the second question will be which part of the

which part of the computer is

considered the brain then I'll go to a new

launched who is known as the father of computers then for my last

question what was the first programming

first programming language all right here are the

language all right here are the questions questions is an array of

questions questions is an array of strings a one-dimensional array now

strings a one-dimensional array now we'll create a two-dimensional array of

we'll create a two-dimensional array of options we will create a two-dimensional

options we will create a two-dimensional array of strings named options

we have five questions that means we need five arrays one array for each

question I'll Place each of these on a new line for

readability our first array within our 2D array of options will hold all of the

2D array of options will hold all of the options for our first question each

options for our first question each value within this first array is going

value within this first array is going to be strings and I'm going to zoom in a

to be strings and I'm going to zoom in a little so we can both read it what is

little so we can both read it what is the main function of a router here's

the main function of a router here's where you're going to list all of the

where you're going to list all of the different possible answers but only one

different possible answers but only one of them is going to be correct I'll say

of them is going to be correct I'll say one. space storing

one. space storing files for option two that will be

files for option two that will be encrypting

data option three will be

three will be for

for directing internet traffic this will be

directing internet traffic this will be the correct answer number three number

the correct answer number three number four will

four will be managing

be managing passwords this will be my first array

passwords this will be my first array all the options for question one now for

all the options for question one now for question

options honestly I'm just going to copy these and then paste them within each

these and then paste them within each array just to speed things up what part

array just to speed things up what part of the computer is considered the

of the computer is considered the brain here's the different options

brain here's the different options option one will be CPU that's going to

option one will be CPU that's going to be the correct answer the central

be the correct answer the central processing unit two hard

processing unit two hard drive three

drive three Ram four

Ram four GPU question three what year was

GPU question three what year was Facebook

Facebook launched option one will be 2000 option

launched option one will be 2000 option two 2004 and that's the correct

two 2004 and that's the correct answer

answer 2006 or 2008

2006 or 2008 who is known as the father of

who is known as the father of computers let's say Steve

Jobs Bill Gates Allan

Gates Allan Turing or Charles Babbage and that's the

Turing or Charles Babbage and that's the correct

answer what was the first programming language either

language either cobal C

cobal C for

for Tran or

Tran or assembly the correct answer is actually

assembly the correct answer is actually Fortran it's the first commercially

Fortran it's the first commercially available programming language one more

available programming language one more thing we're going to create a

thing we're going to create a one-dimensional array what are the

one-dimensional array what are the correct answers we'll need some sort of

correct answers we'll need some sort of key we could include this with our

key we could include this with our declare variable

declare variable step we will create an integer array of

step we will create an integer array of answers we will list the correct answers

answers we will list the correct answers as integers the correct answer to

as integers the correct answer to question one is directing internet

question one is directing internet traffic so we will list three for the

traffic so we will list three for the next question what part of the computer

next question what part of the computer is considered the brain that is the CPU

is considered the brain that is the CPU option

option one Facebook was launched in the year

one Facebook was launched in the year 2004 that's

2004 that's two who is the father of computers that

two who is the father of computers that is Charles

is Charles Babbage that's

Babbage that's four and the first commercially

four and the first commercially available program ining language is for

available program ining language is for Tran that is three here are the correct

Tran that is three here are the correct answers are key there's a few more

answers are key there's a few more variables we'll need we will create an

variables we'll need we will create an integer variable of score we can set

integer variable of score we can set that to be zero if we would like and an

that to be zero if we would like and an integer of guess guess is going to store

integer of guess guess is going to store whatever the user types in 1 through

whatever the user types in 1 through four so it's going to be an integer we

four so it's going to be an integer we will also need a scanner to accept user

will also need a scanner to accept user input scanner scanner equals new scanner

input scanner scanner equals new scanner it doesn't really matter where we

it doesn't really matter where we declare it just as long as we declare it

declare it just as long as we declare it before we use it system.in and then we

before we use it system.in and then we will import this

will import this class import java.util.scanner and then

class import java.util.scanner and then close our scanner at the end of our

close our scanner at the end of our program when we're done with it scanner.

close all right here are the variables we'll need including our options and our

we'll need including our options and our questions our next step is to create a

questions our next step is to create a welcome message

welcome message let's output the

let's output the following let's say welcome to the Java

following let's say welcome to the Java quiz

game and then I'll add some separators a bunch of asterisks because

separators a bunch of asterisks because I think it'll look cool

mostly we have our welcome message and I'll just perform a test run it's a good

I'll just perform a test run it's a good idea to test your code as you're coding

idea to test your code as you're coding it just sure that everything is working

it just sure that everything is working fine and that is our welcome

fine and that is our welcome message now we'll Loop through all of

message now we'll Loop through all of the questions that we

have we'll probably want to use a for Loop we will create an index of I in I

Loop we will create an index of I in I equals z we'll continue this loop as

equals z we'll continue this loop as long as I is less

long as I is less than the length of our array of

than the length of our array of questions questions access the length

questions questions access the length property

property which will return a number in this case

which will return a number in this case five because there's five questions we

five because there's five questions we will increment I by

will increment I by one as a test let's print our

one as a test let's print our questions at index of I I will start at

questions at index of I I will start at zero so we're returning the first

zero so we're returning the first question at index

question at index zero then during each iteration of this

zero then during each iteration of this Loop we will display each question let's

Loop we will display each question let's do a test

do a test run so here are the five questions

run so here are the five questions we're displaying each element of our

we're displaying each element of our array of

array of questions after each question we have to

questions after each question we have to list all of the different

list all of the different options that's the next

options that's the next step we'll display a question then

step we'll display a question then create a nested Loop to display all of

create a nested Loop to display all of the

the options I'm going to use an enhanced for

options I'm going to use an enhanced for Loop for this what is the data type of

Loop for this what is the data type of each value within each array within

each value within each array within options

options well we're working with

well we're working with strings the inner for Loop is going to

strings the inner for Loop is going to be an enhanced for Loop the data type of

be an enhanced for Loop the data type of each value is a

each value is a string string option colon meaning

string string option colon meaning in rray of options at index of

in rray of options at index of i options is a two-dimensional array if

i options is a two-dimensional array if we retrieve a value at a given index

we retrieve a value at a given index will be given an array display every

will be given an array display every option in each inner array

option in each inner array so to demonstrate that let's print each

option so here's what we have after printing each question we will Loop

printing each question we will Loop through and print all of the

options now before moving on to the next question we have to get some user input

question we have to get some user input we don't want to display all the

we don't want to display all the questions right away just one at a time

questions right away just one at a time so we will do this within the outer for

so we will do this within the outer for loop after printing all of the options

loop after printing all of the options this is where we will get the guess from

this is where we will get the guess from the

user we will create a prompt to enter your guests and I will use print instead

your guests and I will use print instead of print line because I like the user

of print line because I like the user input on the same

input on the same line we will assign our variable of

line we will assign our variable of guess guess equal

guess guess equal scanner. next int the user going to type

scanner. next int the user going to type in a number 1 through

in a number 1 through 4 then we have to check our guess is it

4 then we have to check our guess is it correct or

correct or not we can do the

not we can do the following we'll use an if statement if

following we'll use an if statement if our guess is equal to our array of

our guess is equal to our array of answers it's a one-dimensional

answers it's a one-dimensional array at index of I we're using the

array at index of I we're using the index of I because we're still within

index of I because we're still within our for Loop during the first iteration

our for Loop during the first iteration of this Loop I will be zero so is our

of this Loop I will be zero so is our guess equal to answers at index zero if

guess equal to answers at index zero if that is correct let's print the

that is correct let's print the following let's say correct and for fun

following let's say correct and for fun I'll add some text decoration some of

I'll add some text decoration some of those

separators again it's not necessary I just think it'll look

cool else if our guest doesn't equal our answer well we can check that with an

answer well we can check that with an lse statement if we don't have the

lse statement if we don't have the correct answer that means we have the

correct answer that means we have the wrong answer and I will output

wrong answer and I will output wrong and I will just space this out a

wrong and I will just space this out a little

little bit all right let's do a test

bit all right let's do a test run for the first question the correct

run for the first question the correct answer is three I'll type in three then

answer is three I'll type in three then we print

we print correct which part of the computer is

correct which part of the computer is considered the brain I will

considered the brain I will intentionally get this wrong let's say

intentionally get this wrong let's say the

the GPU

GPU wrong and I'll guess the others

wrong and I'll guess the others wrong

wrong wrong wrong then we have to calculate a

wrong wrong then we have to calculate a final

final score okay then we have to display the

score okay then we have to display the final score so after we get the correct

final score so after we get the correct answer we will increment our score by

answer we will increment our score by one score

one score Plus+ then we will display the final

score your final score is I'll use string catnation to keep this simple

string catnation to keep this simple we'll add our score variable plus the

we'll add our score variable plus the words out

words out of plus we're going to get the length of

of plus we're going to get the length of our questions questions is an

our questions questions is an array questions. length

array questions. length property I'm just going to add a space

property I'm just going to add a space right before out because I'm forgetting

right before out because I'm forgetting that let's run this one last

that let's run this one last time what is the main function of a

time what is the main function of a router that that is three directing

router that that is three directing internet traffic which part of the

internet traffic which part of the computer is considered the brain that is

computer is considered the brain that is the

the CPU what year was Facebook launched I'm

CPU what year was Facebook launched I'm going to get this one wrong

going to get this one wrong intentionally I'm going to say 2000 and

intentionally I'm going to say 2000 and that is wrong who is known as the father

that is wrong who is known as the father of computers that is Charles babage

of computers that is Charles babage 4 what was the first programming

4 what was the first programming language well the first commercially

language well the first commercially available programming language that

available programming language that would be three for

would be three for Tran correct your final score is four

Tran correct your final score is four out of five

out of five all right everybody so that is an

all right everybody so that is an interactive quiz game that you can

interactive quiz game that you can create using

Java what is going on everybody in this video we're going to create a game of

video we're going to create a game of rock paper scissors for beginners so

rock paper scissors for beginners so let's get started as a beginner when

let's get started as a beginner when creating a project it could be helpful

creating a project it could be helpful to you to break down a project into

to you to break down a project into smaller steps just as comments I'm going

smaller steps just as comments I'm going to list the different steps that we'll

to list the different steps that we'll need to take so let's say first we will

need to take so let's say first we will declare our

declare our variables then then get a choice from

variables then then get a choice from the

the user get random choice for the

user get random choice for the computer check win conditions who

won ask to play again then at the end we will display a

again then at the end we will display a goodbye

message it may be helpful to you as a beginner to list the different steps

beginner to list the different steps that your program is going to take just

that your program is going to take just for more organization all right let's

for more organization all right let's work on step one we will declare our

work on step one we will declare our variables we'll need a scanner because

variables we'll need a scanner because we're accepting user input scanner

we're accepting user input scanner scanner equals new

scanner equals new scanner within the set of parentheses we

scanner within the set of parentheses we will type system.

will type system. in import the class for scanners import

in import the class for scanners import java.util.scanner and then we will close

java.util.scanner and then we will close our scanner when we're done with it

our scanner when we're done with it scanner. close because we don't want to

scanner. close because we don't want to leave any resources open we will be

leave any resources open we will be generating random numbers we will need

generating random numbers we will need to create a random object random random

to create a random object random random equals new

equals new random and then import this class as

random and then import this class as well import

well import java.util

java.util random we're going to create an array of

random we're going to create an array of choices they will be strings rock paper

choices they will be strings rock paper or scissors we will create a string

or scissors we will create a string array named

array named choices equals an array this will be an

choices equals an array this will be an array of

array of strings at the first index we'll have

strings at the first index we'll have Rock then

Rock then paper then

scissors we'll store our choice within a variable this will be a string we'll

variable this will be a string we'll name this variable player

name this variable player choice I will declare this variable but

choice I will declare this variable but not yet assign it and the computer's

not yet assign it and the computer's Choice string computer choice

Choice string computer choice we're going to create a while loop that

we're going to create a while loop that will ask the user to play again when

will ask the user to play again when they reach the end we'll create a string

they reach the end we'll create a string variable of play again and I will set

variable of play again and I will set this to be

this to be yes basically while play again is yes

yes basically while play again is yes continue the

continue the game let's work on our next step get the

game let's work on our next step get the choice from the

choice from the user we need to prompt the

user we need to prompt the user we'll use a print line statement

user we'll use a print line statement and say

and say enter your move I'll add a set of

enter your move I'll add a set of parentheses that says rock paper

parentheses that says rock paper scissors just so the user knows what to

scissors just so the user knows what to type in I'll use print instead of print

type in I'll use print instead of print line because I prefer user input on the

line because I prefer user input on the same

same line once we have our prompt we're going

line once we have our prompt we're going to assign our player choice variable

to assign our player choice variable player choice equals we will use our

player choice equals we will use our scanner to get some user input we need

scanner to get some user input we need to accept a string so we can use the

to accept a string so we can use the next

next line

line method to accept a line of text in case

method to accept a line of text in case a user types in any uppercase characters

a user types in any uppercase characters for example Rock we could follow this

for example Rock we could follow this with the two lowercase method just to

with the two lowercase method just to make it all lowercase whatever the user

make it all lowercase whatever the user types

types in accept the next line of user input

in accept the next line of user input then make it lowercase just for

then make it lowercase just for consistency now we should have our

consistency now we should have our player

player choice we need a way to determine to see

choice we need a way to determine to see if this user input is valid did the user

if this user input is valid did the user pick rock paper or scissors or something

pick rock paper or scissors or something else entirely well we could use an if

else entirely well we could use an if statement for

that we're going to be checking to see if our player choice doesn't equal Rock

if our player choice doesn't equal Rock and doesn't equal paper and doesn't

and doesn't equal paper and doesn't equal scissors so we can write the

equal scissors so we can write the following statement we're going to use

following statement we're going to use the not logical operator first not will

the not logical operator first not will give you the opposite the

give you the opposite the inverse if player choice use the equals

inverse if player choice use the equals method pass in a string of rock if the

method pass in a string of rock if the Player's Choice doesn't equal Rock then

Player's Choice doesn't equal Rock then we'll use the and logical

we'll use the and logical operator and the Player's

operator and the Player's Choice doesn't again I'm using the not

Choice doesn't again I'm using the not logical

logical operator

operator equals

equals paper again we're going to use the and

paper again we're going to use the and logical

logical operator and just to help with

operator and just to help with readability cuz we're going to have one

readability cuz we're going to have one really long line I'm going to place

really long line I'm going to place these conditions on a new line each this

these conditions on a new line each this will help with

readability and take our player choice not

equals scissors we're linking three conditions

scissors we're linking three conditions together

together if our player choice doesn't equal Rock

if our player choice doesn't equal Rock and our player choice doesn't equal

and our player choice doesn't equal paper and our player choice doesn't

paper and our player choice doesn't equal

equal scissors if all of these conditions are

scissors if all of these conditions are true that means a user didn't type in

true that means a user didn't type in something that's valid so let's do the

something that's valid so let's do the following again I'm within my set of

following again I'm within my set of curly

curly braces we'll output the

braces we'll output the following we'll say something like

following we'll say something like invalid choice

run enter your move rock paper scissors let's choose Rock nothing happens that's

let's choose Rock nothing happens that's good paper nothing

good paper nothing happens

happens scissors nothing happens all right I'm

scissors nothing happens all right I'm going to type in something that's not

going to type in something that's not rock paper or scissors uh I choose the

rock paper or scissors uh I choose the gun invalid

gun invalid Choice that's good that's what we

Choice that's good that's what we want we're picking something that's not

want we're picking something that's not rock and is not paper and is not

rock and is not paper and is not scissors so we execute this if statement

scissors so we execute this if statement if that's the

if that's the case now for the next step we have to

case now for the next step we have to get a random choice for the

get a random choice for the computer we don't need user input this

computer we don't need user input this time we will assign our variable of

time we will assign our variable of computer

computer Choice equals access our array of

Choice equals access our array of choices

choices at a given

at a given index zero would be Rock because it's

index zero would be Rock because it's the first value in our

the first value in our array one would be paper two would be

array one would be paper two would be scissors well why don't we use our

scissors well why don't we use our random object random and call the next

random object random and call the next int

int method then pass in

method then pass in three this method of a random object

three this method of a random object would return a random number between 0

would return a random number between 0 and two zero for rock one for p paper

and two zero for rock one for p paper two for

two for scissors then we'll output it using a

scissors then we'll output it using a print line

print line statement let's say computer Choice col

statement let's say computer Choice col in space then add our variable of

in space then add our variable of computer

computer Choice let's do a test

Choice let's do a test run I'll type in rock the computer picks

paper I will pick paper the computer picks

picks scissors I will will pick

scissors I will will pick scissors the computer picks scissors as

scissors the computer picks scissors as well all right we know that that

well all right we know that that works using this method of a random

works using this method of a random object we're generating a random number

object we're generating a random number as the

as the index now here's the tricky part we have

index now here's the tricky part we have to check all the win

to check all the win conditions I feel like the best way to

conditions I feel like the best way to handle this would be to create an if

handle this would be to create an if statement followed by an else if

statement followed by an else if statement followed by an else

statement followed by an else statement within our if statement this

statement within our if statement this will be for a tie let's output the

will be for a tie let's output the following it's a

following it's a tie our Eli statement will be used if

tie our Eli statement will be used if you win we'll

you win we'll output you

output you win else will be used for you

win else will be used for you lose you

lose you lose if we have a tie that means the

lose if we have a tie that means the Player's Choice is equal to the

Player's Choice is equal to the computer's

computer's Choice that's how you get a tie within

Choice that's how you get a tie within the of statement we can check the

the of statement we can check the following condition if our player choice

following condition if our player choice variable use the equals method of

variable use the equals method of strings then pass in the variable of

strings then pass in the variable of computer

computer choice we're comparing two strings

choice we're comparing two strings the're reference data types so we're

the're reference data types so we're going to use the equals method you can't

going to use the equals method you can't use double equals because then you're

use double equals because then you're comparing memory addresses of two

comparing memory addresses of two different strings we're going to be

different strings we're going to be using equals the equals method if these

using equals the equals method if these two strings are equal will print it's a

two strings are equal will print it's a tie now for the wi conditions within

tie now for the wi conditions within this LF statement this is where things

this LF statement this is where things are going to get kind of tricky we're

are going to get kind of tricky we're going to list all of the different win

going to list all of the different win conditions within our LF statement first

conditions within our LF statement first we'll check if the player picks Rock and

we'll check if the player picks Rock and the computer picks scissors if our

the computer picks scissors if our player

player choice use the equals

choice use the equals method if the player picks Rock a string

method if the player picks Rock a string of

Choice equals let me zoom out a little bit scissors that means we

bit scissors that means we win within our condition of our LF

win within our condition of our LF statement we'll be adding the different

statement we'll be adding the different win conditions but temporarily I'm going

win conditions but temporarily I'm going to add a few else if statements just to

to add a few else if statements just to help me explain this so if we pick Rock

help me explain this so if we pick Rock and the computer pick scissors that

and the computer pick scissors that means we win but we will also win if the

means we win but we will also win if the player

player pick

pick paper and the

paper and the computer let's add that right

computer let's add that right here picks rock that means we also

here picks rock that means we also win and then temporarily I'll add

win and then temporarily I'll add another LF

another LF statement else if the player picks

paper that also means we win we could condense all of these LF

we could condense all of these LF statements into one but we'll do that in

statements into one but we'll do that in a moment I just want to be sure that it

a moment I just want to be sure that it all works first let's do a test run I

all works first let's do a test run I will pick Rock the computer picks

will pick Rock the computer picks scissors that means we

scissors that means we win I will pick paper the computer picks

win I will pick paper the computer picks paper it's a

paper it's a tie I'll keep playing until I lose I

tie I'll keep playing until I lose I will pick scissors the computer picks

will pick scissors the computer picks paper we win let's try scissors again

paper we win let's try scissors again the computer picks Rock we lose we know

the computer picks Rock we lose we know that these different wi conditions are

that these different wi conditions are working this is fairly readable but if

working this is fairly readable but if you prefer we can condense all of these

you prefer we can condense all of these steps down together into one else if

steps down together into one else if statement optionally what you could do

statement optionally what you could do with our first win condition let's

with our first win condition let's enclose them within a set of

parentheses then I will use the or logical Operator Let Me zoom in so you

logical Operator Let Me zoom in so you can see

can see it I'm adding or to the

it I'm adding or to the end

or let's take the entire condition within our LS if statement then paste it

within our LS if statement then paste it after the or logical

after the or logical operator and these do need to be

operator and these do need to be enclosed within a set of

parentheses and we can delete this LF statement We'll add the or logical

statement We'll add the or logical operator to the end

cut this condition for the next LF statement and delete this LF

statement and delete this LF statement and paste

statement and paste it so here's our LF statement there is a

it so here's our LF statement there is a lot going on here this should work too

lot going on here this should work too but if you prefer to keep it the other

but if you prefer to keep it the other way just for readability feel free to do

way just for readability feel free to do so if you like to condense some of the

so if you like to condense some of the code here's how you could do that so let

code here's how you could do that so let me just be sure that everything's

me just be sure that everything's working fine

working fine I will pick Rock computer picks Rock

I will pick Rock computer picks Rock it's a

it's a tie I will pick paper computer picks

tie I will pick paper computer picks scissors you

scissors you lose I will pick scissors computer picks

lose I will pick scissors computer picks paper you win all right this LF

paper you win all right this LF statement does work again if you would

statement does work again if you would prefer to add more LF statements feel

prefer to add more LF statements feel free to keep it the other way now we

free to keep it the other way now we need to ask the user if they want to

need to ask the user if they want to play

play again after displaying either it's a tie

again after displaying either it's a tie you win or you lose We'll add a prompt I

you win or you lose We'll add a prompt I will use print instead of print

will use print instead of print line I'll ask play

line I'll ask play again yes slash

no we have one variable we haven't used yet our play again variable and

yet our play again variable and currently it's

currently it's yes play again equals use our scanner

yes play again equals use our scanner use the next line

use the next line method and I will take the user's input

method and I will take the user's input and make it lowercase right away to

and make it lowercase right away to lowercase

lowercase method we're going to enclose all of our

method we're going to enclose all of our code right before the variables within a

code right before the variables within a loop a do while loop so we'll say do all

loop a do while loop so we'll say do all this code while some condition remains

this code while some condition remains true let's cut all of our

code cut it and then paste it within this do while

loop so with the do while loop we do all of this code once

of this code once and then check the condition at the

and then check the condition at the end what's our condition going to be

end what's our condition going to be we'll continue playing while our play

we'll continue playing while our play again variable equals a string of yes

again variable equals a string of yes play again equals

play again equals yes one more change we're going to

yes one more change we're going to make if the user picks something that

make if the user picks something that isn't valid we're going to skip the

isn't valid we're going to skip the current iteration of this Loop we can

current iteration of this Loop we can use continue for that

use continue for that we want to go back to the beginning if a

we want to go back to the beginning if a user types in something that is

user types in something that is invalid then the last step is to create

invalid then the last step is to create a goodbye message we're doing this

a goodbye message we're doing this outside of the while loop cuz when we're

outside of the while loop cuz when we're outside of the while loop that means

outside of the while loop that means we're no longer playing let's print the

we're no longer playing let's print the following thanks for

following thanks for playing all right let's run this one

playing all right let's run this one last

last time I will pick Rock computer pick

time I will pick Rock computer pick scissors you win play again again I'm

scissors you win play again again I'm going to type yes enter your move I will

going to type yes enter your move I will pick paper computer picks rock you win I

pick paper computer picks rock you win I will play again I will pick

will play again I will pick scissors the computer picks Rock You

scissors the computer picks Rock You Lose I'm going to type no to play again

Lose I'm going to type no to play again and we escape that Doh Loop thanks for

and we escape that Doh Loop thanks for playing all right everybody so that is a

playing all right everybody so that is a game of rock paper scissors you can make

game of rock paper scissors you can make using

Java hello everybody in this video we're going to create a slot machine program

going to create a slot machine program using Java a user is going to bet an

using Java a user is going to bet an amount for the symbols of our slot

amount for the symbols of our slot machine we'll be using emojis if a user

machine we'll be using emojis if a user gets any matching symbols they'll

gets any matching symbols they'll receive a payout then at the end we'll

receive a payout then at the end we'll give a final balance if that sounds good

give a final balance if that sounds good to you let's get started all right

to you let's get started all right everybody when working on a project it

everybody when working on a project it might be helpful to you to tackle your

might be helpful to you to tackle your project one step at a time as comments

project one step at a time as comments we'll list the different steps that our

we'll list the different steps that our program is going to take this will give

program is going to take this will give us a rough outline of our project the

us a rough outline of our project the first thing we'll do is declare our

first thing we'll do is declare our variables then display a welcome message

variables then display a welcome message display welcome

display welcome message we will play if our balance

message we will play if our balance meaning the money that we have is

meaning the money that we have is greater than

greater than zero if we don't have any money we can't

zero if we don't have any money we can't play it is a slot machine after all a

play it is a slot machine after all a user is going to enter bet amount then

user is going to enter bet amount then I'll write a few Subs steps underneath

I'll write a few Subs steps underneath here we need to

here we need to verify if the bet is greater than the

verify if the bet is greater than the balance you can't bet money that you

balance you can't bet money that you don't

don't have then

have then verify if bet is greater than zero you

verify if bet is greater than zero you can't bet negative money so we'll need

can't bet negative money so we'll need to check

to check that then subtract bet from our balance

that then subtract bet from our balance once we subtract the BET from the

once we subtract the BET from the balance then we will spin our

balance then we will spin our row our row is going to contain emojis

row our row is going to contain emojis but we'll need to display it we'll

but we'll need to display it we'll create a method to print our row of

create a method to print our row of emojis once we display our row we need

emojis once we display our row we need to get a payout if we win something if

to get a payout if we win something if we have any

we have any matches then ask to play

matches then ask to play again if the user doesn't want to play

again if the user doesn't want to play we will display an exit message display

we will display an exit message display exit message so here's a rough outline

exit message so here's a rough outline of our project we will Begin by

of our project we will Begin by declaring our

declaring our variables we will be accepting user

variables we will be accepting user input we'll need a scanner for that

input we'll need a scanner for that scanner scanner equals new

scanner scanner equals new scanner type system.in within the set of

scanner type system.in within the set of parentheses import this class import

parentheses import this class import java.util.scanner then when we're done

java.util.scanner then when we're done with our scanner we'll want want to

with our scanner we'll want want to close it scanner.

close we'll need a balance how much money do we have I will set that to be

money do we have I will set that to be 100 100 as in

100 100 as in $100 this could also be done with other

$100 this could also be done with other units of currency we'll need an amount

units of currency we'll need an amount for our bet int bet how much are we

for our bet int bet how much are we betting how much are we

betting how much are we risking int

risking int payout how much money do we win we'll be

payout how much money do we win we'll be adding our pay pay out to our balance if

adding our pay pay out to our balance if we

we win and a string array named

win and a string array named row our row is going to contain our

row our row is going to contain our symbols our emojis that will display to

symbols our emojis that will display to the output window that's why we're

the output window that's why we're creating a string array to store all of

creating a string array to store all of them here are the variables we'll need

them here are the variables we'll need we'll move on to the next step our next

we'll move on to the next step our next step is to display a welcome

step is to display a welcome message let's say something like this

message let's say something like this I'll use a print line statement we'll

I'll use a print line statement we'll say welcome to

say welcome to Java

Java slots underneath this line we'll add

slots underneath this line we'll add another print line statement I will

another print line statement I will print the word symbols and here we'll

print the word symbols and here we'll list all the different symbols we would

list all the different symbols we would like to use within our program I'll be

like to use within our program I'll be using emojis to pull up the Emoji menu

using emojis to pull up the Emoji menu if you're on Windows hold on the window

if you're on Windows hold on the window key then hit the semicolon

key then hit the semicolon button so pick some emojis that you like

button so pick some emojis that you like here's a few that I typically see

here's a few that I typically see cherries watermelon

cherries watermelon lemons bells and

lemons bells and stars if you would like to stick to a

stars if you would like to stick to a certain theme feel free to change

certain theme feel free to change these but these are a few symbols you

these but these are a few symbols you may see on a slot

may see on a slot machine and I'm just going to work on

machine and I'm just going to work on the spacing a little bit that looks

the spacing a little bit that looks pretty

pretty good just to make this a little more

good just to make this a little more fancy I'm going to add a bunch of

fancy I'm going to add a bunch of asterisks as separators before and after

asterisks as separators before and after not necessary I just think it looks cool

not necessary I just think it looks cool and that's a good enough

and that's a good enough reason let's perform a test run just to

reason let's perform a test run just to be sure that this looks

be sure that this looks fine I think that looks pretty good all

fine I think that looks pretty good all right we have our welcome

right we have our welcome message our next step is to play our

message our next step is to play our game if our balance is greater than zero

game if our balance is greater than zero this can be done with the while

this can be done with the while loop while our balance is greater than

loop while our balance is greater than zero we will continue

zero we will continue playing then we have to enter the BET

playing then we have to enter the BET amount that's the next step

amount that's the next step first we'll display our current

first we'll display our current balance current balance colon

balance current balance colon space pick unit of currency I'll pick

space pick unit of currency I'll pick American

American dollars plus we will display our balance

dollars plus we will display our balance variable we will ask a user for some

variable we will ask a user for some input place your bet

input place your bet amount I'll use print rather than print

amount I'll use print rather than print line because I like the user input on

line because I like the user input on the same line we will assign our bet

the same line we will assign our bet variable use our scanner to accept some

variable use our scanner to accept some input let's say next int we won't deal

input let's say next int we won't deal with cents we'll just bet whole

with cents we'll just bet whole dollars then we have a couple substeps

dollars then we have a couple substeps we have to verify if our bet is greater

we have to verify if our bet is greater than our

balance we'll write an if statement if bet is greater than our

statement if bet is greater than our balance we'll output the following

balance we'll output the following let's say insufficient

let's say insufficient funds we'll want to skip the current

funds we'll want to skip the current cycle of this Loop we'll use continue to

cycle of this Loop we'll use continue to go back to the

go back to the beginning then we'll verify if the bet

beginning then we'll verify if the bet is greater than

is greater than zero we don't want a user to bet

zero we don't want a user to bet negative

negative money else

if our bet let's say less than or equal to zero we don't want to use our betting

to zero we don't want to use our betting no

money bet must be greater than zero else we have to subtract the BET

zero else we have to subtract the BET from the

from the balance we could say balance equals

balance we could say balance equals balance minus bet but we can shorten

balance minus bet but we can shorten this using the augmented assignment

this using the augmented assignment operator we can say balance minus equals

operator we can say balance minus equals bet Within our LF statement we're going

bet Within our LF statement we're going to use the continue keyword to skip the

to use the continue keyword to skip the current iteration of this Loop so

current iteration of this Loop so temporarily within my else statement I'm

temporarily within my else statement I'm just going to print our balance right

after just to be sure that it's all working let's do a test

working let's do a test run okay welcome to Java slots current

run okay welcome to Java slots current balance $100 place your bet amount I

balance $100 place your bet amount I will bet money that I don't have one1

will bet money that I don't have one1 kajillion dollars insufficient funds

kajillion dollars insufficient funds current balance $100 place your bet

current balance $100 place your bet amount we can't bet negative money I'll

amount we can't bet negative money I'll bet1 bet must be greater than zero then

bet1 bet must be greater than zero then we're brought back to the beginning I

we're brought back to the beginning I will bet

will bet $10 and our new balance is

$10 and our new balance is $90 all right we know that that

$90 all right we know that that works we can delete this print line

works we can delete this print line statement we no longer need it we were

statement we no longer need it we were just testing something our next step is

just testing something our next step is that we're going to spin our row of

that we're going to spin our row of symbols our

emojis after we subtract our bet from our balance it's here that we'll spin

our balance it's here that we'll spin our Row first I'll print the following

our Row first I'll print the following message let's say the word

message let's say the word spinning then we will call a method to

spinning then we will call a method to spin our row but we will need to declare

spin our row but we will need to declare this method we will do that outside of

this method we will do that outside of the main

the main method this will be a static method the

method this will be a static method the return type is going to be an array of

return type is going to be an array of strings

strings string array and the name of the method

string array and the name of the method will be spin

row we'll be creating a few local variables within this method but first

variables within this method but first we do need to return

we do need to return something because we promised that we're

something because we promised that we're going to return a string array in order

going to return a string array in order for this program to run a compile fine I

for this program to run a compile fine I will add The Following return statement

will add The Following return statement return a new empty array of strings

return a new empty array of strings we'll be replacing this later but we do

we'll be replacing this later but we do have to return something in order for

have to return something in order for this method to at least work we'll be

this method to at least work we'll be creating a few local variables the first

creating a few local variables the first is a string

is a string array named

array named symbols equals then within a set of cly

symbols equals then within a set of cly braces we need our emojis let's go back

braces we need our emojis let's go back to the

to the beginning copy our

beginning copy our emojis then place them within this array

emojis then place them within this array they do need to be surrounded with a set

they do need to be surrounded with a set of double quotes because this is an

of double quotes because this is an array of strings

array of strings so let's take a moment to take care of

that all right that is good we will declare a string array named row our row

declare a string array named row our row is going to be empty it's going to be a

is going to be empty it's going to be a new string array that can hold three

new string array that can hold three elements row is an empty array that can

elements row is an empty array that can hold three strings which will be picked

hold three strings which will be picked at random

we will be generating random numbers we need a random object random random

need a random object random random equals new

equals new random then import this

random then import this class at the top import java.util

random temporarily there's something I'm going to demonstrate let's display our

going to demonstrate let's display our aray of symbols at index of zero that

aray of symbols at index of zero that should output this first Emoji a cherry

should output this first Emoji a cherry I'll just bet a dollar doesn't matter

I'll just bet a dollar doesn't matter and we have our

watermelon watermelon then four should be our

star star we need to choose a random number

star we need to choose a random number between zero and four when we select our

between zero and four when we select our array of symbols within the straight

array of symbols within the straight brackets where we list an index we will

brackets where we list an index we will take our random object call the next int

take our random object call the next int method we will generate a random number

method we will generate a random number between zero and

between zero and five the first number is inclusive the

five the first number is inclusive the second number is exclusive if your range

second number is exclusive if your range starts with zero you don't technically

starts with zero you don't technically need this first number you could just

need this first number you could just say

say five let's run this a few times just to

five let's run this a few times just to see what

see what happens so that time I got a bell

cherry and a watermelon if we have more or less

watermelon if we have more or less emojis we would need to change this

emojis we would need to change this number why don't we use the length of

number why don't we use the length of our symbols instead symbols then give me

our symbols instead symbols then give me the length property of this

the length property of this array if we were to add more or less

array if we were to add more or less symbols our length is going to change

symbols our length is going to change automatically when we run and compile

automatically when we run and compile this

this program so we'll do a test run again

program so we'll do a test run again again and that seems to

work you're getting a random symbol each time let's delete the print line

time let's delete the print line statement portion of

statement portion of this we need to generate three random

this we need to generate three random symbols we can use a for Loop for that

symbols we can use a for Loop for that for in I equals 0 we will continue as

for in I equals 0 we will continue as long as I is less than three then

long as I is less than three then increment I by One

increment I by One we will take our row at index of I in

we will take our row at index of I in the beginning I is going to equal zero

the beginning I is going to equal zero then one then two then the four Loop

then one then two then the four Loop ends we will assign row at index of I

ends we will assign row at index of I equal to cut this line of

equal to cut this line of code we're picking a random symbol from

code we're picking a random symbol from our array of strings our array of

our array of strings our array of emojis at the end we will return our row

emojis at the end we will return our row we're returning our array of strings

we're returning our array of strings just to test it I'm going to Output

just to test it I'm going to Output using print row at index

one plus row at index 2 I just want to be sure that we get three random

symbols there we go we get three random symbols we'll format the output later so

symbols we'll format the output later so don't

don't wor we can delete this statement we were

wor we can delete this statement we were just testing

just testing something now this method is complete we

something now this method is complete we can close

can close it we're returning a string array back

it we're returning a string array back to the place in which we called this

to the place in which we called this method we can assign this

method we can assign this array back to the beginning we will

array back to the beginning we will assign our string array of

row our row equals call the spin row method and this will return a string

method and this will return a string array which we're assigning to row once

array which we're assigning to row once we have our row we're going to print our

we have our row we're going to print our row we'll need to create another method

row we'll need to create another method for that we will create a static method

for that we will create a static method it's not going to return anything the

it's not going to return anything the return type is void the name will be

return type is void the name will be print

print row there will be one parameter we

row there will be one parameter we accept a string array which we will name

accept a string array which we will name row after assigning our row we will call

row after assigning our row we will call call the print row

call the print row method but we have to pass in our

method but we have to pass in our row because we have one parameter we

row because we have one parameter we have to pass in a string array which we

have to pass in a string array which we are so here's where we'll print and

are so here's where we'll print and display our row of emojis let's output

display our row of emojis let's output the following I will display a space

the following I will display a space character plus now the string class has

character plus now the string class has a few useful methods type string with a

a few useful methods type string with a capital s dot call the join method

capital s dot call the join method for each character within a string we

for each character within a string we can join them together with another

can join them together with another character I will join them by a space a

character I will join them by a space a vertical bar then a space comma

vertical bar then a space comma Row for every string in my string array

Row for every string in my string array of row we're going to join them with the

of row we're going to join them with the vertical bar along with a space before

vertical bar along with a space before and after here's the output

and after here's the output currently I'll just bet a dollar here's

currently I'll just bet a dollar here's what we have we have three

what we have we have three emojis each separated with the IAL

emojis each separated with the IAL bar I'll add some of those separators

bar I'll add some of those separators too those

too those asterisks 14 Aster risks should be

enough all right let's take another look I'll bet

I'll bet $10 that looks pretty good I'm happy

$10 that looks pretty good I'm happy with that our next step is to get a

with that our next step is to get a payout if there's any

payout if there's any matches we can collapse this method we

matches we can collapse this method we no longer need

no longer need it now we need to get our

it now we need to get our payout after printing our row we will

payout after printing our row we will call a method of get payout which we

call a method of get payout which we still need to

still need to declare we'll pass in two things our

declare we'll pass in two things our string array of row and our bet how much

string array of row and our bet how much money did we

money did we bet we need to declare this

bet we need to declare this method after the print row method we

method after the print row method we will declare a static method this method

will declare a static method this method is going to return an integer our payout

is going to return an integer our payout the method name will be get

the method name will be get payout we have to set up the parameters

payout we have to set up the parameters we're accepting a string

we're accepting a string array we will name the string array

array we will name the string array row and a bet our bet is an integer int

row and a bet our bet is an integer int bet we do need to return something just

bet we do need to return something just temporarily at the end I'm going to

temporarily at the end I'm going to return

return zero we need to check to see if we have

zero we need to check to see if we have any

any matches what we could do first is check

matches what we could do first is check to see if all three elements match are

to see if all three elements match are all these strings the same symbol here's

all these strings the same symbol here's how we can do

how we can do that let's write an if

that let's write an if statement if our

statement if our row at index of zero that's the first

row at index of zero that's the first symbol now you can't use the comparison

symbol now you can't use the comparison operator for Strings cuz they're

operator for Strings cuz they're reference data

reference data types you would think you could say if

types you would think you could say if row at index 0 is equal to row at index

row at index 0 is equal to row at index one but you actually need to use

one but you actually need to use equals if row at index

equals if row at index zero equals row at index

one if the first two symbols match row at index0 and row at index one well then

at index0 and row at index one well then the first two symbols match but not only

the first two symbols match but not only that we have to compare row at index one

that we have to compare row at index one and row at index 2 do those match as

and row at index 2 do those match as well we're checking to see if all three

well we're checking to see if all three symbols match we will use the and

symbols match we will use the and logical operator and we can copy this

logical operator and we can copy this check paste it and if row at index one

check paste it and if row at index one equals row at index 2 if all three

equals row at index 2 if all three symbols match then we execute this if

symbols match then we execute this if statement why don't we use an enhanced

statement why don't we use an enhanced switch a switch can return something

switch a switch can return something we'll use the return

we'll use the return keyword create a switch within the

keyword create a switch within the switch where are we examining let's

switch where are we examining let's examine one of these symbols we can just

examine one of these symbols we can just pick any I'll just pick the first

pick any I'll just pick the first one we are examining our row at index

one we are examining our row at index zero all three symbols are going to be

zero all three symbols are going to be the same so it doesn't matter which one

the same so it doesn't matter which one you pick we'll examine this value this

you pick we'll examine this value this Emoji against any matching cases the

Emoji against any matching cases the first case will be our first symbol of a

first case will be our first symbol of a cherry if these two values match we'll

cherry if these two values match we'll do the following we'll write an arrow

do the following we'll write an arrow and we're going to be returning

and we're going to be returning something let's return our bet times

something let's return our bet times three let's

three let's say we get a payout of three times what

say we get a payout of three times what we bet for our next

we bet for our next case that was a

case that was a watermelon the payout will be

lemon let's set the payout to be five a

Bell three matching Bells will be worth 10 three stars let's say is

20 bet times 20 We'll add a default case too in case

20 We'll add a default case too in case there's no

there's no matches default Arrow return

zero looks like I'm missing a semicolon at the end if all three symbols match

at the end if all three symbols match return our bet times a certain amount

return our bet times a certain amount depending on which symbols

depending on which symbols match the get payout method is going to

match the get payout method is going to return an

return an integer we will assign our variable of

integer we will assign our variable of payout equal to get

payout if our payout is greater than zero we'll do the following that means

zero we'll do the following that means we won something if that's the case

we won something if that's the case let's let's output U1 pick a unit of

let's let's output U1 pick a unit of currency plus our payout whatever we

currency plus our payout whatever we win then we will add that to our balance

win then we will add that to our balance balance equals balance plus our payout

balance equals balance plus our payout but we can shorten this using the

but we can shorten this using the augmented assignment operator for

augmented assignment operator for addition balance plus equals our

payout else if we don't get a payout if our payout is zero that means we didn't

our payout is zero that means we didn't win anything we'll

win anything we'll output sorry you lost this round okay

output sorry you lost this round okay let's do a few test runs I'm going to

let's do a few test runs I'm going to keep on running this until we get three

keep on running this until we get three matching symbols just to be sure that it

matching symbols just to be sure that it all works I will bet a

all works I will bet a dollar our message is sorry you lost

dollar our message is sorry you lost this round and the current balance is

this round and the current balance is $99 I'll bet another dollar you lost you

$99 I'll bet another dollar you lost you lost you

lost you lost it's hard to get three matching

lost it's hard to get three matching symbols here we go I have three matching

symbols here we go I have three matching cherries you won $3 and my current

cherries you won $3 and my current balance is

balance is $86 now if you would like to check to

$86 now if you would like to check to see if the first two symbols match or

see if the first two symbols match or the second two you can add the following

the second two you can add the following code let's copy our if

code let's copy our if statement paste it change if to be else

statement paste it change if to be else if we'll only be checking the first two

if we'll only be checking the first two symbols we can delete the second

symbols we can delete the second condition

condition if the first two symbols match we'll

if the first two symbols match we'll give a reduced payout let's say for two

give a reduced payout let's say for two matching cherries that will be two for

matching cherries that will be two for watermelon that will be three

watermelon that will be three 4 5 and then

4 5 and then 10 if the second symbol matches the

10 if the second symbol matches the third

third one we'll write another L

one we'll write another L statement index one and index two will

statement index one and index two will give the same

give the same payout hello this is from the future

payout hello this is from the future there's just one bug that I need to fix

there's just one bug that I need to fix the else if statement where we check if

the else if statement where we check if our second symbol matches the third

our second symbol matches the third within our switch we have to examine one

within our switch we have to examine one of these two symbols I forgot to change

of these two symbols I forgot to change that originally both these symbols

that originally both these symbols should be the same so it doesn't matter

should be the same so it doesn't matter which one we pick I'll just pick the

which one we pick I'll just pick the index at one back to the previous LF

index at one back to the previous LF statement index zero is fine because the

statement index zero is fine because the first two symbols should match I just

first two symbols should match I just needed to fix that that is all let's

needed to fix that that is all let's check to be sure that works I'll bet a

check to be sure that works I'll bet a dollar so my first two symbols match we

dollar so my first two symbols match we have a reduced payout of $3 but if it

have a reduced payout of $3 but if it was three watermelons we would win $4

instead we can close this get payout method we're done with

method we're done with it here we'll ask the user to play again

it here we'll ask the user to play again if they would like to

continue we'll create a prompt do you want to play again I'll

prompt do you want to play again I'll use print rather than print

use print rather than print line there's one more variable we'll

line there's one more variable we'll need that I'm

need that I'm forgetting let's create a string

forgetting let's create a string variable of play

again we will assign play again equal to use our scanner call the next line

use our scanner call the next line method

method we'll want a user to type in either

we'll want a user to type in either capital y or capital N after accepting

capital y or capital N after accepting user input we'll make it uppercase using

user input we'll make it uppercase using the two uppercase

method using an if statement we'll check we'll check if play again doesn't

equal for comparing strings we use equals if play again doesn't equal a

equals if play again doesn't equal a capital Y then we will break to break

capital Y then we will break to break out of the loop that we're

out of the loop that we're in then go to the exit the exit

in then go to the exit the exit message one more thing we need to add

message one more thing we need to add though I'm going to play a

though I'm going to play a bet we get that prompt to play again but

bet we get that prompt to play again but the program exits after typing in a

the program exits after typing in a number there's still a new line

number there's still a new line character within the input

character within the input buffer because we're using next int next

buffer because we're using next int next integer we need to clear that input

integer we need to clear that input buffer

buffer after this line of codee where we call

after this line of codee where we call the next int method we can take our

the next int method we can take our scanner called the next line method to

scanner called the next line method to get rid of that new line character and

get rid of that new line character and that should

that should work I'll bet a dollar then we can play

work I'll bet a dollar then we can play again if we type in

again if we type in y we display our current balance we can

y we display our current balance we can place another

place another bet hey $50 that time I'll type n to not

bet hey $50 that time I'll type n to not play again then we exit

play again then we exit the last thing we're going to do is

the last thing we're going to do is display an exit

display an exit message we'll take care of that right

message we'll take care of that right here once we're out of the

here once we're out of the loop let's output the

loop let's output the following game

following game over your final

over your final balance is pick unit of

balance is pick unit of currency then I will add our variable of

currency then I will add our variable of balance okay let's run this one last

balance okay let's run this one last time welcome to Java slots I'll bet a

time welcome to Java slots I'll bet a dollar sorry you lost would you like to

dollar sorry you lost would you like to play again I will type y for yes current

play again I will type y for yes current balance $99 I will bet a dollar

balance $99 I will bet a dollar again I

again I lost I'll just keep playing till I win

lost I'll just keep playing till I win hey I won $10 we have two matching Stars

hey I won $10 we have two matching Stars I'll play one more time I will bet

I'll play one more time I will bet $10 and I won 20 we have two matching

$10 and I won 20 we have two matching symbols I will type in no to not play

symbols I will type in no to not play again and we get our game over message

again and we get our game over message your final balance is

your final balance is $117 so we came out ahead all right

$117 so we came out ahead all right everybody that is a slot machine game

everybody that is a slot machine game you can create using

Java yo we have finally made it to object-oriented programming in Java so

object-oriented programming in Java so what is an object exactly look around

what is an object exactly look around wherever you're sitting right now you

wherever you're sitting right now you are surrounded by different objects for

are surrounded by different objects for example next to me I have my phone a cup

example next to me I have my phone a cup of coffee and a microphone in

of coffee and a microphone in programming an object can represent a

programming an object can represent a real world entity they can do one of a

real world entity they can do one of a few things objects can hold data and

few things objects can hold data and they can perform actions the data they

they can perform actions the data they hold are known as attributes the actions

hold are known as attributes the actions that they can perform are known as

that they can perform are known as methods objects can have things and they

methods objects can have things and they can do things some attributes that a

can do things some attributes that a person may have would be a name their

person may have would be a name their age their height and their weight a few

age their height and their weight a few methods meaning actions that a human

methods meaning actions that a human could do a person well they could eat

could do a person well they could eat and they could sleep objects are

and they could sleep objects are reference data types we store the data

reference data types we store the data for an object in a location known as the

for an object in a location known as the Heap in this demonstration we're going

Heap in this demonstration we're going to be creating some car objects but

to be creating some car objects but we'll need a Class A Class can serve as

we'll need a Class A Class can serve as a blueprint to create objects so what

a blueprint to create objects so what we're going to do is create a new Java

we're going to do is create a new Java class we will create a class of car

class we will create a class of car we have two classes our main class and

we have two classes our main class and our car

our car Class A Class can behave as a blueprint

Class A Class can behave as a blueprint for creating objects we'll start by

for creating objects we'll start by listing the different attributes that a

listing the different attributes that a car may have so what does a car have

car may have so what does a car have exactly well a car could have a make

exactly well a car could have a make that would be a

that would be a string we can assign it if we would like

string we can assign it if we would like think of a car you'd like or a car you

think of a car you'd like or a car you drive I'll pick my favorite car the make

drive I'll pick my favorite car the make will be Ford another attribute could be

will be Ford another attribute could be a

a model and I will pick a

model and I will pick a Mustang cars could have a year that

Mustang cars could have a year that would be an integer into Year I'll pick

would be an integer into Year I'll pick the year

the year 2025 a price that could be a double

2025 a price that could be a double double price

double price equals let's say

equals let's say $58,000

$58,000 99 a car's engine could be running that

99 a car's engine could be running that could be a Boolean Boolean is running I

could be a Boolean Boolean is running I will set that to be true

will set that to be true or false if the car is turned off things

or false if the car is turned off things that an object has in this case car

that an object has in this case car these are known as attributes they are

these are known as attributes they are things that an object

things that an object has now heading back to our main class

has now heading back to our main class we will create a car

we will create a car object we're already a little familiar

object we're already a little familiar with working with objects for example a

with working with objects for example a scanner is an object to create a scanner

scanner is an object to create a scanner we would type scanner scanner equals new

scanner then you type system.in or with random objects we

system.in or with random objects we would type random random equals new

random Now to create a car object we're going to be utilizing this

going to be utilizing this class we'll type car then think of a

class we'll type car then think of a name for this car we'll just say car all

name for this car we'll just say car all lowercase equals new car we're following

lowercase equals new car we're following a similar

a similar pattern car car equals new

pattern car car equals new car we don't need the scanner or the

car we don't need the scanner or the random object I was just demonstrating

random object I was just demonstrating something we now have a car object that

something we now have a car object that we can use our car object has these

we can use our car object has these attributes these

things if I was to print my car object here's what we can

here's what we can see well since objects are a reference

see well since objects are a reference data type if you were to print your car

data type if you were to print your car directly you get a memory

address if you need to access one of these attributes

these attributes you have to follow the object name with

you have to follow the object name with a DOT a DOT is known as the dot operator

a DOT a DOT is known as the dot operator it allows you to access things within an

it allows you to access things within an object if I need the model of my car I

object if I need the model of my car I would take my object name use the dot

would take my object name use the dot operator followed by the attribute name

operator followed by the attribute name if I was to print the model of my

if I was to print the model of my car that would output

car that would output Mustang let's print some of the other

Mustang let's print some of the other attributes car. make who manufactures

attributes car. make who manufactures the

the car

car Ford what is the year of my car car.

price $58,000 and

$58,000 and 99 is my car running or not car do is

99 is my car running or not car do is running

false the car is not currently running you can modify and change these

you can modify and change these attributes too with our car object let's

attributes too with our car object let's access the is running attribute I will

access the is running attribute I will set that to be true like we're turning

set that to be true like we're turning the car

the car on is running is now true because we

on is running is now true because we changed the attribute of is

changed the attribute of is running not only do objects have the

running not only do objects have the capability to hold data meaning

capability to hold data meaning attributes they can perform actions they

attributes they can perform actions they can have their own methods going back to

can have their own methods going back to our car class we'll Define a few

our car class we'll Define a few methods what sorts of actions can a car

methods what sorts of actions can a car take well we could start a car within

take well we could start a car within this class we will Define a method we

this class we will Define a method we don't need that static keyword this time

don't need that static keyword this time we need a return type we'll say void

we need a return type we'll say void we're not returning anything we will

we're not returning anything we will Define a method of

Define a method of start let's do the following let's

start let's do the following let's output

output you start the

you start the engine we'll create another

engine we'll create another method

method void

stop let's say you stop the engine so now with our

engine so now with our car we can delete these print line

car we can delete these print line statements we'll take our car object use

statements we'll take our car object use the dot operator call the start method

the dot operator call the start method method this should output you start the

method this should output you start the engine or we can stop car.

stop you start the engine you stop the engine not only that Within These

engine not only that Within These methods let's change one of these

methods let's change one of these variables one of these

variables one of these attributes within our start method let's

attributes within our start method let's take is running set that to be

take is running set that to be true within the stop method we'll take

true within the stop method we'll take is running set that to be

false going back to our main class before starting the car let's

class before starting the car let's output car do is

output car do is running after starting the car let's

running after starting the car let's output car dot is running and then

output car dot is running and then stopping the car will output car dot is

stopping the car will output car dot is running the car is currently not running

running the car is currently not running that's false you start the engine the

that's false you start the engine the car is now running that's set to true

car is now running that's set to true you stop the engine the car is no longer

you stop the engine the car is no longer running that is

running that is false let's add two more methods we can

false let's add two more methods we can start we can stop we can drive we'll

start we can stop we can drive we'll create a method to drive void

Drive let's output you drive the I'm going to use string concatenation we'll

going to use string concatenation we'll concatenate the model of the

concatenate the model of the car so my car is a Mustang

car so my car is a Mustang we will create a method to

break you break the plus our model variable

you break the plus our model variable our model

our model attribute we can delete these lines of

attribute we can delete these lines of code let's drive the car car.

code let's drive the car car. drive you drive the Mustang and here's

drive you drive the Mustang and here's the model of the car and we can break

the model of the car and we can break car. break

you drive the Mustang you break the Mustang there's one issue with this

Mustang there's one issue with this though with our class of car every car

though with our class of car every car that we make has the same attributes and

that we make has the same attributes and methods we can only create 225 Ford

Mustangs if I was to create another car object let's say car car 2

object let's say car car 2 equals new

equals new car we'll rename the first car as car

car we'll rename the first car as car 1 and I'll output some of their

1 and I'll output some of their attributes Car

attributes Car 1make Plus a

1make Plus a space plus car

space plus car 1 model we'll do this with our second

1 model we'll do this with our second car object too Car 2 car 2. make car 2.

car object too Car 2 car 2. make car 2. model these cars have the same

model these cars have the same attributes it would be nice if we had a

attributes it would be nice if we had a way to customize them so that each car

way to customize them so that each car is unique because currently they're all

is unique because currently they're all the same they're different cars but they

the same they're different cars but they have the same attributes and methods

have the same attributes and methods which is kind of lame that's why in the

which is kind of lame that's why in the next video we're going to discuss

next video we're going to discuss Constructors by passing in arguments we

Constructors by passing in arguments we can create unique objects in summary an

can create unique objects in summary an object is an entity that holds data it

object is an entity that holds data it has attributes and they can perform

has attributes and they can perform actions they can perform

actions they can perform methods they have things and they can do

methods they have things and they can do things and and well everybody those are

things and and well everybody those are objects in

Java hey yeah today we're talking about Constructors in Java a Constructor is

Constructors in Java a Constructor is just a special method within a class

just a special method within a class it's used to initialize objects by using

it's used to initialize objects by using a Constructor we can create objects with

a Constructor we can create objects with unique values when you create an object

unique values when you create an object you can pass arguments to a Constructor

you can pass arguments to a Constructor to set up the initial values here's a

to set up the initial values here's a demonstration what we're going to do is

demonstration what we're going to do is create a new class let's go to file new

create a new class let's go to file new Java

Java class let's create a class of students

class let's create a class of students this will be the student

this will be the student class what are some attributes that a

class what are some attributes that a student should have they should have a

student should have they should have a name let me zoom in a little so you can

name let me zoom in a little so you can read it NH AG int

read it NH AG int ag ag GPA meaning grade point

ag ag GPA meaning grade point average let's create a Boolean of is

average let's create a Boolean of is enrolled

enrolled that is good enough for now there's one

that is good enough for now there's one issue with this let's say that all

issue with this let's say that all students that I create using this class

students that I create using this class they're all going to be named

they're all going to be named SpongeBob going back to my Java file

SpongeBob going back to my Java file I'll create a few

I'll create a few students we type the name of the class

students we type the name of the class and name for this object let's say

and name for this object let's say student one equals new student the name

student one equals new student the name of the class

of the class again then we'll create a second

again then we'll create a second student student two

student student two I'm going to Output student one's name

I'm going to Output student one's name student 1. name as well as student 2's

name the issue that we have is that all students that we create all student

students that we create all student objects they're all named

objects they're all named SpongeBob what if we would like to give

SpongeBob what if we would like to give each object a unique name well we can do

each object a unique name well we can do that with the help of a Constructor a

that with the help of a Constructor a Constructor is just a special method

Constructor is just a special method within a class

within a class to set up a Constructor we type the name

to set up a Constructor we type the name of the class in this case student you

of the class in this case student you need a set of parentheses then a set of

need a set of parentheses then a set of curly

curly braces we automatically call this

braces we automatically call this Constructor when we instantiate an

Constructor when we instantiate an object of that class when we say new

object of that class when we say new then the name of the class

then the name of the class parenthesis behind the scenes we're

parenthesis behind the scenes we're calling this

calling this Constructor and we can pass in

Constructor and we can pass in arguments within the set of parentheses

arguments within the set of parentheses we can pass in arguments so let's pass

we can pass in arguments so let's pass in what are we missing a name age GPA is

in what are we missing a name age GPA is enrolled as well but we'll take care of

enrolled as well but we'll take care of that momentarily let's pass in a name

that momentarily let's pass in a name age and

age and GPA student one's name will be

GPA student one's name will be SpongeBob SpongeBob's age will be let's

SpongeBob SpongeBob's age will be let's say 30 he seems about 30 SpongeBob's GPA

say 30 he seems about 30 SpongeBob's GPA can be 3.2 that's pretty

can be 3.2 that's pretty good we have a warning our Constructor

good we have a warning our Constructor isn't set up to take these arguments

isn't set up to take these arguments going back to our Constructor since

going back to our Constructor since we're receiving arguments we need a

we're receiving arguments we need a matching set of parameters just like any

matching set of parameters just like any other method we have a string for name

other method we have a string for name integer of age double GPA we'll take

integer of age double GPA we'll take care of these three first we have string

care of these three first we have string name int age double

name int age double GPA to assign some of these attributes

GPA to assign some of these attributes we're going to use the this keyword this

we're going to use the this keyword this dot the name of the attribute this do

dot the name of the attribute this do name equals our parameter of

name equals our parameter of name this. AG equals the age that we

name this. AG equals the age that we receive this. GPA equals the GPA that we

receive this. GPA equals the GPA that we receive going back to our Java file we

receive going back to our Java file we can now construct an object if I attempt

can now construct an object if I attempt to run this currently we are receiving a

to run this currently we are receiving a warning our Constructor expects three

warning our Constructor expects three arguments but we don't pass in any zero

arguments but we don't pass in any zero are found if I were to run

are found if I were to run this we get this error message actual

this we get this error message actual and formal argument lists differ in

and formal argument lists differ in length in order for us to create a scent

length in order for us to create a scent object we have to pass in these three

object we have to pass in these three things a string for the name an integer

things a string for the name an integer for the age and a double for the

for the age and a double for the GPA if we are missing these three we

GPA if we are missing these three we can't construct an object but previously

can't construct an object but previously we could with without the Constructor

we could with without the Constructor for our second student let's pass in a

for our second student let's pass in a name of Patrick Patrick will be

name of Patrick Patrick will be 34 Patrick's GPA isn't too good it's a

1.5 all right let's test this we're printing student one's name and student

printing student one's name and student 2's

2's name we get SpongeBob and

name we get SpongeBob and Patrick let's display some of the other

attributes we have name age

name age GPA we'll do this with student 2 as well

GPA we'll do this with student 2 as well student 2.age student 2.

GPA SpongeBob SpongeBob is 30 years old SpongeBob's GPA is

SpongeBob's GPA is 3.2 these are all the unique attributes

3.2 these are all the unique attributes of our student object student

of our student object student one student 2's attributes are Patrick

one student 2's attributes are Patrick age is 34 GPA is 1.5

with the this keyword this refers to the object we're currently constructing or

object we're currently constructing or otherwise working with imagine that when

otherwise working with imagine that when we construct student

we construct student one imagine we replace the this keyword

one imagine we replace the this keyword with the name of the object we're

with the name of the object we're assigning student one's name equal to

assigning student one's name equal to the name that we receive same thing

the name that we receive same thing applies with our age and our

applies with our age and our GPA the same thing would apply with

GPA the same thing would apply with student 2 when we construct student 2

student 2 when we construct student 2 imagine during the process we replace

imagine during the process we replace this with student

this with student 2 this refers to the object we're

2 this refers to the object we're currently working with or

currently working with or constructing with these parameter names

constructing with these parameter names they don't necessarily need to be the

they don't necessarily need to be the same as your attribute names just to

same as your attribute names just to demonstrate let's rename name as a age

demonstrate let's rename name as a age as B GPA as C this.name equals a this.

as B GPA as C this.name equals a this. age equals B this. GPA equals c

age equals B this. GPA equals c this should work

this should work too each object still has their unique

attributes but I like to keep the parameter names the same as the

parameter names the same as the attributes it makes the code easier to

attributes it makes the code easier to read and understand we haven't assigned

read and understand we haven't assigned to this attribute of is

to this attribute of is enrolled each object that we create

enrolled each object that we create using this Constructor let's assign this

using this Constructor let's assign this objects is enrolled attribute equal to

objects is enrolled attribute equal to you don't always necessarily need to

you don't always necessarily need to assign arguments to these attributes for

assign arguments to these attributes for example let's just say that when you

example let's just say that when you become a student you are enrolled that

become a student you are enrolled that is true we don't necessarily need to

is true we don't necessarily need to pass in an argument for that going back

pass in an argument for that going back to our main class let's print take

to our main class let's print take student ones is enrolled attribute and

student ones is enrolled attribute and then print it we'll do the same thing

then print it we'll do the same thing with student two

Patrick when we create a student object we're automatically setting is a

we're automatically setting is a enrolled to be true they are enrolled in

enrolled to be true they are enrolled in classes and that applies to Patrick as

classes and that applies to Patrick as well student to Let's create another

well student to Let's create another student object just so that we get the

student object just so that we get the hang of this repetition is going to help

hang of this repetition is going to help you remember let's create student 3

you remember let's create student 3 student 3 is an object

student 3 is an object new

new student to create a student we have to

student to create a student we have to pass in three things a string for the

pass in three things a string for the name an integer for the age and a double

name an integer for the age and a double for the

for the GPA student 3 will be be

GPA student 3 will be be Sandy Sandy is 27 let's say Sandy is

Sandy Sandy is 27 let's say Sandy is smart she'll have a 4.0

smart she'll have a 4.0 GPA and then we'll print student 3's

GPA and then we'll print student 3's attributes student 3. name student 3's

attributes student 3. name student 3's age student 3's GPA student 3 is

age student 3's GPA student 3 is enrolled our object of student 3 has

enrolled our object of student 3 has these attributes Sandy 27 4.0 and

these attributes Sandy 27 4.0 and true if if your class has any methods

true if if your class has any methods for example all students have the method

for example all students have the method to

study void study I'll just output the following let's take our name

following let's take our name attribute but I'm going to use

attribute but I'm going to use this.name plus the text of is

this.name plus the text of is studying let's delete these print line

studying let's delete these print line statements we'll take student one call

statements we'll take student one call the study method

the study method then we'll do this with student two and

then we'll do this with student two and student

3 SpongeBob is studying Patrick is studying Sandy is

studying after assigning values to your attributes using a Constructor you can

attributes using a Constructor you can use them within methods too or change

use them within methods too or change them this refers to the object we're

them this refers to the object we're currently working with if student 3

currently working with if student 3 meaning Sandy was to call her study

meaning Sandy was to call her study method imagine we're replacing this with

method imagine we're replacing this with student 3 student 3's name

student 3 student 3's name attribute all right everybody those are

attribute all right everybody those are Constructors they're a special method

Constructors they're a special method found within a class to initialize

found within a class to initialize objects you can pass arguments to a

objects you can pass arguments to a Constructor when you initialize them

Constructor when you initialize them they're used to set up the initial

they're used to set up the initial values when you construct an object a

values when you construct an object a Constructor is automatically called when

Constructor is automatically called when you create a new object but you need a

you create a new object but you need a matching set of arguments if there's any

matching set of arguments if there's any parameter setup just like any other

parameter setup just like any other method by using a Constructor we can

method by using a Constructor we can create objects with unique values and

create objects with unique values and well everybody those are Constructors in

Java what is going on people today I'm going to explain overloaded Constructors

going to explain overloaded Constructors overloaded Constructors allow a class to

overloaded Constructors allow a class to have multiple Constructors with

have multiple Constructors with different parameter lists much like

different parameter lists much like overloaded methods they enable an object

overloaded methods they enable an object to be initialized in various ways here's

to be initialized in various ways here's a demonstration we are going to create a

a demonstration we are going to create a new class let's go to file new Java

new class let's go to file new Java class we will create a class for users

class we will create a class for users we will create a user

we will create a user class let's say that users have three

class let's say that users have three things they will have a string of

things they will have a string of username a string of

username a string of email and an integer in

email and an integer in age let's say that when we create a user

age let's say that when we create a user object these three fields are optional

object these three fields are optional if these three attributes are optional

if these three attributes are optional we may or may not receive them when we

we may or may not receive them when we construct a user object so let's do this

construct a user object so let's do this let's create a Constructor if somebody

let's create a Constructor if somebody were to create a user object with just a

were to create a user object with just a username to create a Constructor we type

username to create a Constructor we type the name of the class in this case

the name of the class in this case user we need to set up a parameter for

user we need to set up a parameter for our username we will receive a string of

our username we will receive a string of username we will assign this St user

username we will assign this St user usern name equal to the username that we

usern name equal to the username that we receive as an argument let's go back to

receive as an argument let's go back to our main Java

our main Java file we will create a new

file we will create a new user let's say user user one equals new

user let's say user user one equals new user we're receiving a warning

user we're receiving a warning though in order to create a user object

though in order to create a user object we have to pass in a string of

we have to pass in a string of username let's say that our user is

username let's say that our user is going to be SpongeBob because that's the

going to be SpongeBob because that's the first thing that came to mind for

first thing that came to mind for me we'll use this Constructor where we

me we'll use this Constructor where we have a username we can also set up the

have a username we can also set up the default values for our attributes too

default values for our attributes too let's say this. email equals a string of

let's say this. email equals a string of not

provided this. AG equals 0 going back to user

0 going back to user one I will output the

one I will output the following user one dot

username user one's email user 1's age here's what we got

here's what we got currently username is SpongeBob email is

currently username is SpongeBob email is not provided age is

not provided age is zero these attributes were optional when

zero these attributes were optional when we construct this object we're just

we construct this object we're just assigning them to some default values

assigning them to some default values what if we create a user that has an

what if we create a user that has an email well we could create another

email well we could create another Constructor with the same

Constructor with the same name but we need a different set of

name but we need a different set of parameters this is very similar to

parameters this is very similar to Method overloading you can have methods

Method overloading you can have methods with the same name but they need

with the same name but they need different

different parameters not only do we have a string

parameters not only do we have a string of username we'll have a string of

of username we'll have a string of email our email attribute equals the

email our email attribute equals the email that we receive we can use either

email that we receive we can use either of these Constructors depending on the

of these Constructors depending on the arguments that are passed in

arguments that are passed in let's create a second user user user 2

let's create a second user user user 2 equals new

equals new user the username will be

user the username will be Patrick Patrick's email is let's say

Patrick Patrick's email is let's say p Patrick is probably still using AOL

p Patrick is probably still using AOL for some reason let's say

for some reason let's say aol.com then we'll print user 2's

aol.com then we'll print user 2's attributes user 2. username user two.

attributes user 2. username user two. email user 2.age

email user 2.age here's what we got we have all the

here's what we got we have all the attributes for user one and user two

attributes for user one and user two Patrick P star

Patrick P star aol.com our age is still

aol.com our age is still zero we can create different objects

zero we can create different objects with a varying number of

with a varying number of arguments let's create a third

arguments let's create a third user this time we'll have a parameter

user this time we'll have a parameter for our age

for our age attribute I'm just going to copy this

attribute I'm just going to copy this cuz I'm lazy we'll have an INT age we

cuz I'm lazy we'll have an INT age we will assign our age variable

will assign our age variable with the age argument we

with the age argument we receive we'll create user

receive we'll create user 3 user user 3 equals new

user username will be Sandy email will be S

Sandy email will be S cheeks

cheeks gmail.com then an age let's say

gmail.com then an age let's say 27 then I'll print user 3's attributes

27 then I'll print user 3's attributes user 3. username email then

user 3. username email then age here is all of sy's attributes

age here is all of sy's attributes username email

age let's set up a Constructor that accepts no

arguments this will be kind of an anonymous

anonymous profile this. username will equal guest

profile this. username will equal guest or a guest

or a guest profile this . email

profile this . email equals not

provided this. AG equals z now we could create a user object then

z now we could create a user object then pass in no arguments user user 4 equals

pass in no arguments user user 4 equals new user this time we don't have any

new user this time we don't have any arguments then I'll display user Force

email age here's what we got username guessed

age here's what we got username guessed email not provided age is

email not provided age is zero in a way by creating an object and

zero in a way by creating an object and passing in no arguments you can set up

passing in no arguments you can set up some default

some default values all right everybody those are

values all right everybody those are overloaded Constructors they allow a

overloaded Constructors they allow a class to have multiple Constructors they

class to have multiple Constructors they just need different parameter lists they

just need different parameter lists they enable objects to be initialized in

enable objects to be initialized in various Ways by passing in a varying

various Ways by passing in a varying amount of

amount of arguments this would be great in a

arguments this would be great in a situation where some fields are optional

situation where some fields are optional when creating an object and well

when creating an object and well everybody those are overloaded

everybody those are overloaded Constructors in

Java hey everybody in this video I'm going to show you how we can create an

going to show you how we can create an array of objects using Java it's pretty

array of objects using Java it's pretty useful at times and you should probably

useful at times and you should probably know how to do it we'll Begin by

know how to do it we'll Begin by creating a new class let's go to file

creating a new class let's go to file new class we will create a car

new class we will create a car class let's say that cars have the

class let's say that cars have the following

following attributes we'll just pick two to keep

attributes we'll just pick two to keep it simple a string of model and a string

it simple a string of model and a string of color we'll need a car

of color we'll need a car Constructor we will pass in a string of

Constructor we will pass in a string of model and a string of color we will

model and a string of color we will assign this. model equals the model we

assign this. model equals the model we receive this. color equals the color

receive this. color equals the color that we receive we'll add one method

that we receive we'll add one method void drive all cars can drive well I'll

void drive all cars can drive well I'll put the following using a print line

put the following using a print line statement you drive

statement you drive the plus this. color plus a space plus

the plus this. color plus a space plus this. model okay we are done with the

this. model okay we are done with the car

car class we'll construct a few car objects

class we'll construct a few car objects let's start with car one car car 1

let's start with car one car car 1 equals a new car we have to pass in a

equals a new car we have to pass in a model and a

model and a color think of some cars that you like I

color think of some cars that you like I will pick a red Mustang for one car

will pick a red Mustang for one car let's create Car 2 Car 2 equals a new

let's create Car 2 Car 2 equals a new car I will pick a

car I will pick a Corvette that is blue one more car car 3

Corvette that is blue one more car car 3 car car 3 equals a new

car car 3 equals a new car a yellow

charger all right we have our three car objects we can create an array but for

objects we can create an array but for an array you have to list the data type

an array you have to list the data type of what you're storing we're going to be

of what you're storing we're going to be storing car objects the data type of the

storing car objects the data type of the array is going to be car objects car

array is going to be car objects car then for an array we need a set of

then for an array we need a set of straight

straight brackets what is the name of this array

brackets what is the name of this array going to be well I think cars would be

going to be well I think cars would be appropriate cars equals if you're

appropriate cars equals if you're creating an empty array you're going to

creating an empty array you're going to use the new keyword list the data type

use the new keyword list the data type of

of car within the straight brackets specify

car within the straight brackets specify the size of this array let's say three

the size of this array let's say three elements Max or we could go ahead and

elements Max or we could go ahead and just assign these right away too using a

just assign these right away too using a set of cly braces let's Place car 1 Car

set of cly braces let's Place car 1 Car 2 and car 3 within this array we'll

2 and car 3 within this array we'll place these three car objects within

place these three car objects within this array of cars now you could use a

this array of cars now you could use a for Loop to iterate through this array

for Loop to iterate through this array here's how we'll start with the standard

here's how we'll start with the standard for Loop we'll need an index in I equals

for Loop we'll need an index in I equals z we'll continue as long as I is less

z we'll continue as long as I is less than our cars length property then

than our cars length property then increment I by one we'll access our

increment I by one we'll access our array of cars at index of I which is

array of cars at index of I which is going to increase each time but it

going to increase each time but it starts at zero we will call the drive

starts at zero we will call the drive method and let's see what

happens you drive the red Mustang you drive the blue Corvette you drive the

drive the blue Corvette you drive the yellow

yellow charger now an enhanced for Loop would

charger now an enhanced for Loop would probably be more appropriate for

this if you want to use an enhanced for Loop type four parentheses curly

Loop type four parentheses curly braces what is the data type of each

braces what is the data type of each element within this array car objects

element within this array car objects we'll need a nickname for each element

we'll need a nickname for each element within this array let's say car colon

within this array let's say car colon think of colon as in then our array of

think of colon as in then our array of cars for every car object in our array

cars for every car object in our array of cars do the following we'll take each

of cars do the following we'll take each car object call the drive

car object call the drive method and that's going to do the same

method and that's going to do the same thing you drive the red Mustang you

thing you drive the red Mustang you drive the blue Corvette you drive the

drive the blue Corvette you drive the yellow

yellow charger another thing you can do to when

charger another thing you can do to when creating an array of objects you can

creating an array of objects you can pass in Anonymous objects rather than

pass in Anonymous objects rather than first instantiating the objects then

first instantiating the objects then assigning them to the array here's how

assigning them to the array here's how you can do

you can do that for each element we're going to

that for each element we're going to call the car Constructor with the new

call the car Constructor with the new keyword call the car Constructor then

keyword call the car Constructor then pass in the details for each car the

pass in the details for each car the necessary arguments we'll pass in our

necessary arguments we'll pass in our Mustang that's red that's the first

Mustang that's red that's the first element I'll just copy it to save some

element I'll just copy it to save some time then we're creating a new car but

time then we're creating a new car but this will be a

this will be a Corvette that's

Corvette that's blue and I'll put each of these on a new

blue and I'll put each of these on a new line just for readability

and then we have our charger that's

yellow and this will do the same thing too we have our three

too we have our three cars constructing a new object without

cars constructing a new object without giving the object a unique identifier

giving the object a unique identifier like car 1 Car 2 or car 3 these are

like car 1 Car 2 or car 3 these are known as Anonymous

known as Anonymous objects So within an array you can

objects So within an array you can create Anonymous objects if you would

create Anonymous objects if you would rather not give each of the car is a

rather not give each of the car is a unique identifier another thing you can

unique identifier another thing you can do too with an array of objects is let's

do too with an array of objects is let's change the color of each car using our

change the color of each car using our enhanced for Loop car do

enhanced for Loop car do color let's change the color to be black

color let's change the color to be black for each

for each car we'll use another enhanced for Loop

car we'll use another enhanced for Loop to display each car car die

drive you drive the black Mustang you drive the black Corvette you drive the

drive the black Corvette you drive the black

black charger all all right everybody those

charger all all right everybody those are a few things you can do with an

are a few things you can do with an array of objects in

Java hello everybody today I'm going to explain the static keyword using Java

explain the static keyword using Java static is a keyword it modifies a

static is a keyword it modifies a variable or method so that it belongs to

variable or method so that it belongs to the class rather than any specific

the class rather than any specific object we see the static keyword within

object we see the static keyword within the main method when you modify a

the main method when you modify a variable or method with the static

variable or method with the static keyword static is used to create utility

keyword static is used to create utility methods or other shared resources let me

methods or other shared resources let me give you a demonstration we're going to

give you a demonstration we're going to create a new class let's go to file new

create a new class let's go to file new class we'll create a front class we will

class we'll create a front class we will create some friend objects because

create some friend objects because you're

you're lonely let's say that all friends will

lonely let's say that all friends will have a name attribute string

have a name attribute string name we need a Constructor it's the same

name we need a Constructor it's the same as the class name parenthesis curly

as the class name parenthesis curly braces when we construct a friend object

braces when we construct a friend object we have to pass in a string of name we

we have to pass in a string of name we will assign this object's name attribute

will assign this object's name attribute equal to the name parameter that we

equal to the name parameter that we receive let's construct two friends

receive let's construct two friends we'll say friend friend one equals new

we'll say friend friend one equals new friend but we have to pass in a name

friend but we have to pass in a name pick a name my default is SpongeBob

pick a name my default is SpongeBob because most people know who SpongeBob

because most people know who SpongeBob is if I was to Output friend one's name

is if I was to Output friend one's name then it should be SpongeBob we just want

then it should be SpongeBob we just want to be sure that it

to be sure that it works yes it does SpongeBob

works yes it does SpongeBob now going back to our friend class let's

now going back to our friend class let's say we would like to keep track of how

say we would like to keep track of how many friend objects we create well that

many friend objects we create well that could be an attribute let's say we have

could be an attribute let's say we have an integer of num of friends meaning

an integer of num of friends meaning number of friends whenever we create a

number of friends whenever we create a friend object we will increment number

friend object we will increment number of friends by one num of friends

of friends by one num of friends Plus+ so going back let's output friend

Plus+ so going back let's output friend On's number of friends attribute num of

On's number of friends attribute num of friends so this should be one yep num

friends so this should be one yep num friends is one we have one friend but

friends is one we have one friend but what if we create a second friend object

what if we create a second friend object I'll just copy this line of code paste

I'll just copy this line of code paste it change friend one to friend two we'll

it change friend one to friend two we'll pass in a new name let's say

pass in a new name let's say Patrick we'll print friend One's number

Patrick we'll print friend One's number of friends and friend two's number of

of friends and friend two's number of friends how many friend objects have we

friends how many friend objects have we created we have created two but what's

created we have created two but what's the out

the out put well it's one for

put well it's one for both here's why each friend object has

both here's why each friend object has their own copy of the number of friends

their own copy of the number of friends variable we're incrementing each copy of

variable we're incrementing each copy of number of friends by one when we create

number of friends by one when we create the object of friend one we're

the object of friend one we're incrementing its attribute of number of

incrementing its attribute of number of friends by one same thing applies with

friends by one same thing applies with friend two when we create friend two

friend two when we create friend two friend 2's number of friends is zero and

friend 2's number of friends is zero and we're incrementing it by one what if we

we're incrementing it by one what if we would like to keep track of the total

would like to keep track of the total amount of friends that we created and

amount of friends that we created and store it within one variable well there

store it within one variable well there is a way we can do that and that is with

is a way we can do that and that is with the static

the static modifier so going back to our friend

modifier so going back to our friend class we're going to precede the data

class we're going to precede the data type of this attribute with the static

type of this attribute with the static modifier static int number of friends

modifier static int number of friends rather than all objects all friend

rather than all objects all friend objects having their own copy of number

objects having their own copy of number of friends they're all going to share

of friends they're all going to share one so going back let's print a number

one so going back let's print a number of friends now

of friends now it's two we have two total friends if I

it's two we have two total friends if I was to create a third friend friend

was to create a third friend friend three friend three will be

Squidward and then I'll output friend 3's number of

3's number of friends we have three total friends we

friends we have three total friends we are receiving a suggestion when

are receiving a suggestion when accessing a static variable or calling a

accessing a static variable or calling a static method it's actually best to do

static method it's actually best to do so through the class itself

so through the class itself rather than any object created from that

rather than any object created from that class instead of saying you know friend

class instead of saying you know friend one then accessing the static member we

one then accessing the static member we will instead use the name of the class

will instead use the name of the class in this case friend it's better for

in this case friend it's better for clarity to access a static member by the

clarity to access a static member by the name of the class itself rather than any

name of the class itself rather than any object because you and other developers

object because you and other developers will know that this is a static

will know that this is a static attribute or method to display the

attribute or method to display the static variable we would want to access

static variable we would want to access it by the class name then access that

it by the class name then access that static attribute how many friends do we

static attribute how many friends do we have now three let's create a fourth

have now three let's create a fourth friend friend four will be Sandy then

friend friend four will be Sandy then display the number of friends we

display the number of friends we have now we have four friends going back

have now we have four friends going back to the friend class it's as if all these

to the friend class it's as if all these objects are sharing the same variable

objects are sharing the same variable but rather than any one object having

but rather than any one object having ownership of this variable rather the

ownership of this variable rather the friend class owns it and all objects

friend class owns it and all objects have access to it methods can also be

have access to it methods can also be modified by the static

modified by the static keyword we will create a static method

keyword we will create a static method that doesn't return anything the return

that doesn't return anything the return type is void this method will be the

type is void this method will be the show Friends method we'll just output

show Friends method we'll just output the following we'll output you

the following we'll output you have

have plus normally when you access an

plus normally when you access an attribute you type this dot the name of

attribute you type this dot the name of the attribute such as you know name if

the attribute such as you know name if you're working with the static attribute

you're working with the static attribute you don't need this

you don't need this for example this. number of friends you

for example this. number of friends you don't need this we even have a warning

don't need this we even have a warning here that friends. this cannot be

here that friends. this cannot be referenced from a static context if

referenced from a static context if you're working with a static attribute

you're working with a static attribute you don't need this this refers to the

you don't need this this refers to the object you're currently working with but

object you're currently working with but since this attribute belongs to the

since this attribute belongs to the class we don't need this you have your

class we don't need this you have your static attribute of number of friends

static attribute of number of friends then the words total friends

to call a static method type the name of the class in this case friend dot the

the class in this case friend dot the name of the method show

friends you have four total friends let's create another friend friend

five friend five will be Gary friend. show friends you have five

Gary friend. show friends you have five total

total friends another place in which you see

friends another place in which you see static members is through the math class

static members is through the math class for example let's say you would like to

for example let's say you would like to round a number you would type the name

round a number you would type the name of the math class math. round and you

of the math class math. round and you can round a

can round a number round is a utility method we

number round is a utility method we access it through the class name of math

access it through the class name of math you don't need to go ahead and create a

you don't need to go ahead and create a math object such as math math 1 equals

math object such as math math 1 equals new math and then access it through this

new math and then access it through this object that would be

object that would be silly round is a static method it

silly round is a static method it behaves as a utility method we can

behaves as a utility method we can access it through the class name and we

access it through the class name and we don't need to create any math objects

don't need to create any math objects because that's stupid and to prove this

because that's stupid and to prove this let's go to the math class I'm going to

let's go to the math class I'm going to hover over math jump to

Source here's the math class and let's find the round method I'm going to do a

find the round method I'm going to do a search for

search for it here's the round

it here's the round method so round is a method and we have

method so round is a method and we have that static keyword round is a utility

that static keyword round is a utility method for the math class we can access

method for the math class we can access it through the name of the class all

it through the name of the class all right everybody so that is the static

right everybody so that is the static keyword it modifies a variable or method

keyword it modifies a variable or method so that it belongs to the class rather

so that it belongs to the class rather than any specific object it's commonly

than any specific object it's commonly used for utility methods or shared

used for utility methods or shared resources among objects created from

resources among objects created from that class such as the number of friends

that class such as the number of friends all those friend objects share the same

all those friend objects share the same attribute rather than each of them

attribute rather than each of them having their own copy and and well

having their own copy and and well everybody that is the static keyword in

everybody that is the static keyword in Java what is going on people today we

Java what is going on people today we got a very important topic to discuss

got a very important topic to discuss today and that is inheritance

today and that is inheritance inheritance is where one class inherits

inheritance is where one class inherits the attributes and methods from another

the attributes and methods from another class much like how a child can inherit

class much like how a child can inherit traits from A parent well in programming

traits from A parent well in programming we could do something similar one class

we could do something similar one class a child's class can inherit traits from

a child's class can inherit traits from A parent here's an example we're going

A parent here's an example we're going to create a few classes but we'll start

to create a few classes but we'll start with a new class of animal let's go to

with a new class of animal let's go to new class I will create an animal

new class I will create an animal class what do animals have let's say

class what do animals have let's say that all animals are alive they will

that all animals are alive they will start by being alive is

start by being alive is alive let's create a Constructor of

alive let's create a Constructor of animal I will set is alive to be true

animal I will set is alive to be true when we construct a new animal object

when we construct a new animal object but not only are all animals alive all

but not only are all animals alive all animals can eat they will have an eat

animals can eat they will have an eat method void eat we'll print something

method void eat we'll print something like the

like the following the animal is eating easting

following the animal is eating easting eating that is good enough for this

eating that is good enough for this class so what we're going to do is

class so what we're going to do is create two more classes file new class

create two more classes file new class we will create a dog

we will create a dog class and a cat

class dog and cats are types of animals our animal class will be the parent the

our animal class will be the parent the dog and cat class will be its children

dog and cat class will be its children in order for a class to inherit all the

in order for a class to inherit all the attributes and methods from another

attributes and methods from another class after the class name you will use

class after the class name you will use the extend

the extend keyword then specify the parent class

keyword then specify the parent class dog extends animal our dog class will

dog extends animal our dog class will inherit all these traits these

inherit all these traits these attributes and methods from the animal

attributes and methods from the animal class the cat and dog class don't have

class the cat and dog class don't have any anything within them let's see if

any anything within them let's see if they actually do have these attributes

they actually do have these attributes and methods even though there's nothing

and methods even though there's nothing within them let's create a dog object

within them let's create a dog object dog dog equals new dog and a cat cat cat

dog dog equals new dog and a cat cat cat equals new

cat let's print our dogs is alive variable is my dog alive I sure hope

variable is my dog alive I sure hope so cat do is

so cat do is alive look at that they're both

alive look at that they're both true they should also be able to eat

true they should also be able to eat dog. eat method cat. eat

method the animal is eating the animal is

is eating even though these classes of dog

eating even though these classes of dog and cat don't have anything within them

and cat don't have anything within them since they extend to the animal class

since they extend to the animal class we're specifying that the animal class

we're specifying that the animal class is the parent the cat and dog classes

is the parent the cat and dog classes are the children of the animal class

are the children of the animal class they inherit all these attributes and

they inherit all these attributes and methods from its parent of animal even

methods from its parent of animal even though they don't have anything within

though they don't have anything within them this isn't as useful if you only

them this isn't as useful if you only have a few classes such as two because

have a few classes such as two because you know you could just copy and paste

you know you could just copy and paste all this code within

all this code within each and then just change the

each and then just change the Constructor but imagine if you had

Constructor but imagine if you had hundreds of classes hundreds of children

hundreds of classes hundreds of children you'd have to do that for hundreds of

you'd have to do that for hundreds of classes but not only that if you have to

classes but not only that if you have to make any changes to say you know this

make any changes to say you know this animal is eating

animal is eating you'd have to make that change for

you'd have to make that change for hundreds of classes and we are repeating

hundreds of classes and we are repeating ourselves a lot it'd be a lot easier if

ourselves a lot it'd be a lot easier if we can just make that change in one

we can just make that change in one place if we have to change the to this

place if we have to change the to this all of the children classes will inherit

all of the children classes will inherit this updated method we're following the

this updated method we're following the dry principle don't repeat yourself

dry principle don't repeat yourself we're writing the code once and just

we're writing the code once and just reusing it all the children classes will

reusing it all the children classes will inherit this updated method but not only

inherit this updated method but not only that each child class can have their own

that each child class can have their own unique attributes and methods too let's

unique attributes and methods too let's say that all dogs will have one life int

say that all dogs will have one life int lives equals 1 they will also have their

lives equals 1 they will also have their own unique speak method void

own unique speak method void speak when our dog uses the speak method

speak when our dog uses the speak method let's output the following let's say the

let's output the following let's say the dog goes

dog goes woof then within the cat

woof then within the cat class cats will have have nine

class cats will have have nine lives and they can speak but they will

lives and they can speak but they will say something different when they speak

say something different when they speak let's output the cat goes

let's output the cat goes meow going

meow going back let's output our dog objects lives

back let's output our dog objects lives how many lives does our dog have same

how many lives does our dog have same thing applies with our cat cat.

thing applies with our cat cat. lives our dog has one life our cat has

lives our dog has one life our cat has nine

nine lives they also have their own unique

lives they also have their own unique speak methods dog

speak methods dog dope cat

dope the dog goes woof the cat goes meow there's also the concept of

meow there's also the concept of multi-level inheritance we'll create a

multi-level inheritance we'll create a new class to serve as a sort of

new class to serve as a sort of grandparent a child class will inherit

grandparent a child class will inherit from a parent a parent will inherit from

from a parent a parent will inherit from a grandparent so let's change this

a grandparent so let's change this program around a little bit we're going

program around a little bit we're going to create a new class file new Java

to create a new class file new Java class we will create a class of

organism animals will extend the organism

organism class let's cut our is aive variable and

class let's cut our is aive variable and the

the Constructor if you inherit from the

Constructor if you inherit from the animal class you will get an eat

animal class you will get an eat method if you inherit from the organism

method if you inherit from the organism class you are alive and that's it but we

class you are alive and that's it but we need to change the

need to change the Constructor animal inherits from

Constructor animal inherits from organism dog and cat inherit from the

organism dog and cat inherit from the animal class so from the perspective of

animal class so from the perspective of our dog and cat class the organism class

our dog and cat class the organism class is you could say a grandparent going

is you could say a grandparent going back to our main Java file let's take a

back to our main Java file let's take a look at our is alive variables dog. is

look at our is alive variables dog. is alive same thing with our cat

alive same thing with our cat cat dot is

alive yes our dog is alive and our cat is alive let's take this a step

is alive let's take this a step further let's create a class of plant

further let's create a class of plant plant is going to inherit from the

plant is going to inherit from the organism class because plants are a type

organism class because plants are a type of organism but they're not related to

of organism but they're not related to animals let's create a new class of

plant let's say that if you're a plant you get a method to well plants don't

you get a method to well plants don't eat but they can

eat but they can photosynthesize

photosynthesize photosynthesize I think I spelled that

photosynthesize I think I spelled that right probably not but who

right probably not but who cares if you're a plant and you

cares if you're a plant and you photosynthesize then the

photosynthesize then the plant absorbs

plant absorbs sunlight hey this is bro from the future

sunlight hey this is bro from the future I forgot to extend the organism class so

I forgot to extend the organism class so let's take care of that heading back to

let's take care of that heading back to our main Java file let's create a plant

our main Java file let's create a plant object plant plant equals new

plant our plant object should have an is alive attribute is alive which it

alive attribute is alive which it inherits from the organism class that's

inherits from the organism class that's true and plants can

true and plants can photosynthesize plant

photosynthesize plant do photosynthesize

the plant absorbs sunlight it's kind of like we have a

sunlight it's kind of like we have a whole family tree dog and cat inherit

whole family tree dog and cat inherit from animal animal inherits from

from animal animal inherits from organism and plant inherits from

organism and plant inherits from organism but animals and plants aren't

organism but animals and plants aren't related they're siblings but they're not

related they're siblings but they're not the same going back to our main Java

the same going back to our main Java file let's see if our dog has a

file let's see if our dog has a photosynthesize method dog.

photosynthesize method dog. photosynthesize

looks like they can't we do not have a photosynthesize method for dogs they do

photosynthesize method for dogs they do not inherit this method because they're

not inherit this method because they're not related to

not related to plants all right everybody so that's

plants all right everybody so that's inheritance it's where one class

inheritance it's where one class inherits the attributes and methods from

inherits the attributes and methods from another class A Child class will inherit

another class A Child class will inherit all the attributes and methods from a

all the attributes and methods from a parent class parents can also be

parent class parents can also be considered children too and inherit it

considered children too and inherit it from a let's say grandparent class you

from a let's say grandparent class you just have to use the extends keyword and

just have to use the extends keyword and well everybody that's inheritance in

well everybody that's inheritance in Java yo so let's get started today I got

Java yo so let's get started today I got to discuss the super keyword super just

to discuss the super keyword super just refers to the parent class when using

refers to the parent class when using inheritance a child class is also known

inheritance a child class is also known as the sub class the parent class is

as the sub class the parent class is also known as the super class super just

also known as the super class super just means parent for all intents and

means parent for all intents and purposes the super keyword is used

purposes the super keyword is used within Constructors and Method

within Constructors and Method overwriting method overwriting is a

overwriting method overwriting is a whole another topic that we'll discuss

whole another topic that we'll discuss we're more focused on Constructors in

we're more focused on Constructors in this topic we use the super keyword to

this topic we use the super keyword to call the parent Constructor to

call the parent Constructor to initialize attributes let me give you an

initialize attributes let me give you an example we'll be creating a few

example we'll be creating a few different classes let's go to file new

different classes let's go to file new class we will Begin by creating a class

class we will Begin by creating a class of

of person person will be the parent the

person person will be the parent the super

super class let's say that any person object

class let's say that any person object has the following attributes they will

has the following attributes they will have a string of first meaning first

have a string of first meaning first name then string last meaning last name

name then string last meaning last name we'll need a Constructor it's going to

we'll need a Constructor it's going to be the same as the class name Person

be the same as the class name Person parentheses curly braces when we

parentheses curly braces when we construct a person object we will need

construct a person object we will need to pass in the following arguments a

to pass in the following arguments a string for first name first and a string

string for first name first and a string for last name last this objects first

for last name last this objects first name attribute this. first

name attribute this. first equals the argument that we receive for

equals the argument that we receive for first same thing applies with last this.

first same thing applies with last this. last equals the argument we receive for

last equals the argument we receive for last and then we'll create one method in

last and then we'll create one method in this demonstration this method won't

this demonstration this method won't return anything we will name the method

return anything we will name the method show

show name all we'll do is output the

name all we'll do is output the following this do first plus a space

following this do first plus a space plus this. last okay let's test this

plus this. last okay let's test this class

class out person person equals new

out person person equals new person but we do have to pass in a first

person but we do have to pass in a first and last name I've already used

and last name I've already used SpongeBob for too many examples so let's

SpongeBob for too many examples so let's mix it up this time I'll pick Harry

mix it up this time I'll pick Harry Potter or feel free to pick a different

Potter or feel free to pick a different franchise that you like so one person

franchise that you like so one person from Harry Potter is

from Harry Potter is Tom Riddle

Tom Riddle we have a person object with this first

we have a person object with this first name and this last name first

name and this last name first last our person is going to have a show

last our person is going to have a show name method show name then call

name method show name then call it there we go there's our person

it there we go there's our person objects first and last name Tom

objects first and last name Tom Riddle our person class will be the

Riddle our person class will be the parent class we'll create a few other

parent class we'll create a few other classes to inherit from this person

classes to inherit from this person class we're going to create a class of

class we're going to create a class of student that's going to inherit from the

student that's going to inherit from the person class the student class will

person class the student class will inherit these attributes and

inherit these attributes and methods let's create a new class of

student student will extends the parent or super class

will extends the parent or super class of

of person since student is inheriting from

person since student is inheriting from person student is going to have a first

person student is going to have a first and last name already and a show name

and last name already and a show name method what other attributes does a

method what other attributes does a student have that a person might not

student have that a person might not well students have a GPA a grade point

well students have a GPA a grade point average we'll declare that as an

average we'll declare that as an attribute double

attribute double GPA we're going to create a student

GPA we're going to create a student Constructor let's say that when we

Constructor let's say that when we create a student we need to pass in a

create a student we need to pass in a string for first name String

string for first name String first string

first string last and double GPA what's their grade

last and double GPA what's their grade point average now rather than assigning

point average now rather than assigning our first and last name within this

our first and last name within this Constructor such as this. first equals

Constructor such as this. first equals first this. last equals

first this. last equals last and this. GPA equals GPA we are

last and this. GPA equals GPA we are receiving a

receiving a warning there is no parameterless

warning there is no parameterless Constructor available in person we're

Constructor available in person we're not able to assign these attributes of

not able to assign these attributes of first and last within the Constructor

first and last within the Constructor for student this is because student

for student this is because student inherits from the person class since the

inherits from the person class since the Constructor of our parent requires a

Constructor of our parent requires a first and last name we have to pass

first and last name we have to pass these arguments to its parent of person

these arguments to its parent of person how we can do that going back to the

how we can do that going back to the child class we're going to be using the

child class we're going to be using the super keyword any arguments that the

super keyword any arguments that the parent requires we have to send the

parent requires we have to send the parent these arguments from the child

parent these arguments from the child Constructor and how we can do that is

Constructor and how we can do that is use the super keyword

use the super keyword and then pass in those arguments of

and then pass in those arguments of first and last and now Java is

first and last and now Java is Happy super just refers to the parent

Happy super just refers to the parent imagine that we replace the super

imagine that we replace the super keyword with

keyword with person think of it like that and now

person think of it like that and now this should

this should work going back to our main file we

work going back to our main file we should be able to create a student

should be able to create a student object student student equals new

object student student equals new student

student we have to pass in a first name first

we have to pass in a first name first name will be

name will be Harry last name will be

Harry last name will be Potter then we have to pass in a GPA

Potter then we have to pass in a GPA because our student Constructor requires

because our student Constructor requires it Harry Potter has a

it Harry Potter has a 3.25 GPA let's say our student object

3.25 GPA let's say our student object should have these attributes this

should have these attributes this method and this attribute from the

method and this attribute from the student class of GPA

student class of GPA Let's test it student. show

Let's test it student. show name this student's name is Harry

name this student's name is Harry Potter and they should have a

Potter and they should have a GPA let's print students GPA

GPA let's print students GPA attribute

attribute 3.25 but not only that let's create a

3.25 but not only that let's create a method to display their GPA within the

method to display their GPA within the student class we will create a method

student class we will create a method that doesn't return anything it will be

that doesn't return anything it will be show GPA

show GPA we will output the

we will output the following let's say this.

following let's say this. first plus a string apostrophe s so

first plus a string apostrophe s so Harry's

Harry's GPA

GPA is plus this.

GPA let's take our student object call the show GPA method that we have

the show GPA method that we have declared

Harry's GPA is 3.25 let's create one more class we will

3.25 let's create one more class we will create an employee

create an employee class class

employee employee will inherit from the person

person class employee extends

person since employees aren't studying they're not students they instead get a

they're not students they instead get a salary we will create an integer

salary we will create an integer attribute of

attribute of salary and then we need that Constructor

salary and then we need that Constructor for our employee

object all employees will require the following

following arguments a string for first name String

arguments a string for first name String first a string for last name String last

first a string for last name String last and an integer for our employee salary I

and an integer for our employee salary I will attempt to assign these attributes

will attempt to assign these attributes for our employee again it's not going to

for our employee again it's not going to work but let's try it this. first equals

work but let's try it this. first equals first this. last equals

first this. last equals last this do

last this do salary equals

salary equals salary again we're receiving that

salary again we're receiving that warning there is no parameter list

warning there is no parameter list Constructor available in

Constructor available in person since employee extends person and

person since employee extends person and our person Constructor requires a first

our person Constructor requires a first name and a last name we have to send our

name and a last name we have to send our person Constructor these arguments first

person Constructor these arguments first and last so again going back to our

and last so again going back to our employee

employee class we will call the Constructor of

class we will call the Constructor of our parent using the super keyword and

our parent using the super keyword and then passing in those arguments first

then passing in those arguments first and

and last let's create a method within our

last let's create a method within our employee class void Show

salary let's output the following we'll say this. first this person's first

say this. first this person's first name apostrophe yes we'll create the

name apostrophe yes we'll create the employee of Hagrid their

employee of Hagrid their salary is pick unit of currency I'll

salary is pick unit of currency I'll pick American dollars plus this do

pick American dollars plus this do salary now we'll need to construct an

salary now we'll need to construct an employee

object employee

employee employee equals new

employee equals new employee we have to pass in a first name

employee we have to pass in a first name a last name and a salary in order to

a last name and a salary in order to construct an employee object we're going

construct an employee object we're going to pick Hagrid Hagrid's first name is

to pick Hagrid Hagrid's first name is actually

actually rubius last name

rubius last name Hagrid Hagrid's salary will be

Hagrid Hagrid's salary will be $50,000 let's

$50,000 let's say all right let's take our

say all right let's take our employee call its Show salary

method and there we go rubius ALS also known as Hagrid rubi's salary is

known as Hagrid rubi's salary is $50,000 in conclusion super refers to

$50,000 in conclusion super refers to the parent class student and employee

the parent class student and employee inherit from person since the

inherit from person since the Constructor of the parent of person

Constructor of the parent of person requires a first name and a last name

requires a first name and a last name any children objects that we create we

any children objects that we create we have to call the Constructor of the

have to call the Constructor of the parent and pass in those arguments to

parent and pass in those arguments to satisfy Java if the parent didn't

satisfy Java if the parent didn't require these

require these arguments then you wouldn't need to

and well everybody that is the super keyword in Java what's going on people

keyword in Java what's going on people today I'm going to discuss method

today I'm going to discuss method overwriting using Java method

overwriting using Java method overwriting is when a subass provides

overwriting is when a subass provides its own implementation of a method

its own implementation of a method rather than use one that's inherited

rather than use one that's inherited from a parent it allows for code

from a parent it allows for code reusability and you can give specific

reusability and you can give specific implementations of a method let me give

implementations of a method let me give you a demonstration we'll be creating a

you a demonstration we'll be creating a few classes file new class we will Begin

few classes file new class we will Begin by creating a class of

by creating a class of animal then a new

animal then a new class of

class of dog a

dog a class of

class of cat then finally a class of

cat then finally a class of fish dog cat and fish are going to

fish dog cat and fish are going to extend the animal class after the class

extend the animal class after the class name type extends

name type extends animal so let's do the this with cat and

animal so let's do the this with cat and fish the dog cat and fish classes are

fish the dog cat and fish classes are all children of the animal class animal

all children of the animal class animal class is the parent class there's not a

class is the parent class there's not a lot we have to write with this example

lot we have to write with this example if a child class inherits from the

if a child class inherits from the animal parent class they will inherit a

animal parent class they will inherit a method to move let's define a method of

method to move let's define a method of move all we'll say is this animal is

move all we'll say is this animal is running we can keep the dog cat and fish

running we can keep the dog cat and fish class is empty for now so going back to

class is empty for now so going back to our main Java file let's construct a dog

our main Java file let's construct a dog object dog dog equals new dog a cat

object dog dog equals new dog a cat object cat cat equals new cat and a fish

object cat cat equals new cat and a fish fish fish equals new

fish fish equals new fish all three of these animal objects

fish all three of these animal objects dog cat and fish should have a move

dog cat and fish should have a move method let's take our dog call its move

method let's take our dog call its move method say same thing with the cat and

method say same thing with the cat and the

the fish cat. move method fish. move method

fish cat. move method fish. move method currently when we run this program we

currently when we run this program we get the following

get the following output our dog is running our cat is

output our dog is running our cat is running and our fish is running but fish

running and our fish is running but fish don't have legs though they can only

don't have legs though they can only swim the move method that the fish class

swim the move method that the fish class inherits isn't appropriate for that

inherits isn't appropriate for that class this animal is swimming would be

class this animal is swimming would be more appropriate so why don't we do this

more appropriate so why don't we do this within the fish class why don't we do

within the fish class why don't we do some method overwriting specifically for

some method overwriting specifically for the fish class we will create a unique

the fish class we will create a unique move method only for this class we will

move method only for this class we will Define a new move

Define a new move method where we will

method where we will say this animal is

say this animal is swimming however it is good practice to

swimming however it is good practice to add this annotation of at override so

add this annotation of at override so that you and other Developers know that

that you and other Developers know that this method is being overridden our fish

this method is being overridden our fish class does inherit a move method from

class does inherit a move method from its parent of animal if you have the

its parent of animal if you have the same named method defined in a child

same named method defined in a child class you'll use that one first it has

class you'll use that one first it has precedence going back to our main Java

precedence going back to our main Java file let's call the move method for our

file let's call the move method for our fish our dog is running our cat is

fish our dog is running our cat is running but our fish is swimming within

running but our fish is swimming within the fish class we have overridden the

the fish class we have overridden the move method we have given a specific

move method we have given a specific implementation for this method just for

implementation for this method just for this one class the cat and dog classes

this one class the cat and dog classes will use what's inherited from their

will use what's inherited from their parent not only is a good practice to

parent not only is a good practice to add this annotation of at override but

add this annotation of at override but let's say that you misspell this

let's say that you misspell this overwritten method rather than move

overwritten method rather than move let's say moves even though it should be

let's say moves even though it should be move we're receiving a warning that this

move we're receiving a warning that this method does not override the method from

method does not override the method from its super class it's parent if you

its super class it's parent if you didn't have this annotation you may not

didn't have this annotation you may not notice that you misspelled this method

notice that you misspelled this method and you're not actually overwriting

and you're not actually overwriting it adding the at override annotation

it adding the at override annotation provides a system of checks and balances

provides a system of checks and balances when overwriting method this error will

when overwriting method this error will go away once we actually are overwriting

go away once we actually are overwriting a

a method all right everybody so that is

method all right everybody so that is Method overwriting it's when a subass

Method overwriting it's when a subass provides its own implementation of a

provides its own implementation of a method rather than use one that's

method rather than use one that's already defined it allows for code

already defined it allows for code reusability and you can give specific

reusability and you can give specific implementations of a method we'll be

implementations of a method we'll be seeing method overwriting again with the

seeing method overwriting again with the two string method coming up in a future

two string method coming up in a future topic and well everybody that is method

topic and well everybody that is method overwriting in Java hello everybody

overwriting in Java hello everybody today I got to explain the two- string

today I got to explain the two- string method using Java the two- string method

method using Java the two- string method is inherited from the object class

is inherited from the object class whenever you create an object behind the

whenever you create an object behind the scenes the object class is a super class

scenes the object class is a super class the two-ring method is used to return a

the two-ring method is used to return a string representation of an object if

string representation of an object if you were to Output it directly using

you were to Output it directly using system.out print line the default

system.out print line the default behavior of the two- string method is

behavior of the two- string method is that it returns a hash code as a unique

that it returns a hash code as a unique identifier for that object but it can be

identifier for that object but it can be overridden to provide meaningful details

overridden to provide meaningful details which is why we've learned about method

which is why we've learned about method overriding in the last video in this

overriding in the last video in this demonstration let's create a new class

demonstration let's create a new class file new class we will create a car

file new class we will create a car class let's say that all cars should

class let's say that all cars should have the following attributes a string

have the following attributes a string of make who manufactures the car a

of make who manufactures the car a string of model what's the model of the

string of model what's the model of the car int year for the year and string

car int year for the year and string color for the color we'll need a

color for the color we'll need a Constructor and then we'll assign these

Constructor and then we'll assign these attributes we have a string of make a

attributes we have a string of make a string of model an INT of year and a

string of model an INT of year and a string of color then we'll assign these

string of color then we'll assign these attributes this St make equals make this

attributes this St make equals make this St model equals model

St model equals model this.e equals

this.e equals year this. color equals

year this. color equals color that looks good enough for now

color that looks good enough for now going back to our main Java file we'll

going back to our main Java file we'll construct a car object car car equals

construct a car object car car equals new car but we have to pass in the

new car but we have to pass in the details for our car Constructor our car

details for our car Constructor our car Constructor requires a make a model a

Constructor requires a make a model a year and a color so pick a car that you

year and a color so pick a car that you like I like Ford Mustang I'll pick a

like I like Ford Mustang I'll pick a Ford Mustang the make will be Ford Model

Ford Mustang the make will be Ford Model will be

will be Mustang I need a year 2025 and a color

Mustang I need a year 2025 and a color I'll pick the color

I'll pick the color red car is an object if I were to Output

red car is an object if I were to Output my car object directly using

my car object directly using system.out.print line here's what you'll

system.out.print line here's what you'll see if you output your card directly

see if you output your card directly technically you'll be given a hash code

technically you'll be given a hash code a unique identifier for that car object

a unique identifier for that car object hashing is kind of an advanced topic

hashing is kind of an advanced topic that I don't want to introduce right now

that I don't want to introduce right now but typically with hashing it's a unique

but typically with hashing it's a unique identifier that uses the object's memory

identifier that uses the object's memory address to calculate a hash you don't

address to calculate a hash you don't need to know any more than that right

need to know any more than that right now but wouldn't it be useful if we were

now but wouldn't it be useful if we were to print our car object directly we were

to print our car object directly we were given the details of the car normally

given the details of the car normally what we would have to do is output

what we would have to do is output something like this this is if we wanted

something like this this is if we wanted to Output the details of the car we

to Output the details of the car we could say something such as car. color

could say something such as car. color that would would be first plus a space

that would would be first plus a space character plus car do which should be

character plus car do which should be next let's say the year color year then

next let's say the year color year then make and

make and model car. make plus a

model car. make plus a space plus car.

space plus car. model this print line statement is

model this print line statement is giving us meaningful details of this car

giving us meaningful details of this car object this is the

object this is the output red 2025 Ford Mustang it would be

output red 2025 Ford Mustang it would be nice if we were to print our car object

nice if we were to print our car object directly using print or print line we

directly using print or print line we could be given these details instead

could be given these details instead well we can do that with method

well we can do that with method overwriting going to our car

overwriting going to our car class we will be overriding a method we

class we will be overriding a method we need the at override

need the at override annotation we do need this keyword of

annotation we do need this keyword of public this is a publicly accessible

public this is a publicly accessible method the return type is string the

method the return type is string the name of the method is to string

everything within this print line statement we're going to cut and delete

statement we're going to cut and delete this print line

this print line statement going to our car class within

statement going to our car class within the two string method we have to return

the two string method we have to return a string because we set the return type

a string because we set the return type to be a string we promised that we would

to be a string we promised that we would return a string let's paste all the

return a string let's paste all the details of that car we'll need to

details of that car we'll need to replace car with

replace car with this this refers to the object we're

this this refers to the object we're currently working with that and add a

currently working with that and add a semicolon to the end if we were to print

semicolon to the end if we were to print our car object directly using this print

our car object directly using this print line statement or a print statement or

line statement or a print statement or even printf instead of that hash

even printf instead of that hash code we're instead given meaningful

code we're instead given meaningful details of that car that we've

details of that car that we've customized the cars color year make and

customized the cars color year make and model we have overridden the two- string

model we have overridden the two- string method that's normally available to all

method that's normally available to all objects let's construct another car

objects let's construct another car object let's rename car is car one we'll

object let's rename car is car one we'll have car car 2 equals new

have car car 2 equals new car pick some different details for a

car pick some different details for a car I will pick a

car I will pick a Chevrolet

Chevrolet Corvette the year will be

Corvette the year will be 2026 and the color will be blue I'll

2026 and the color will be blue I'll print car

print car one then print Car

2 here's car one and car two Car 2 is a blue 2026 Chevrolet

blue 2026 Chevrolet Corvette all right everybody so that is

Corvette all right everybody so that is the two-ring method objects inherit from

the two-ring method objects inherit from the object class the object class does

the object class the object class does have a two string method but it can be

have a two string method but it can be overridden so that when you print an

overridden so that when you print an object directly you can display

object directly you can display meaningful details such as the details

meaningful details such as the details of that object instead of displaying a

of that object instead of displaying a hash code if you were to print the

hash code if you were to print the object it's pretty useful at times and

object it's pretty useful at times and well everybody that is the two string

well everybody that is the two string method in Java

method in Java all right everybody it's about time we

all right everybody it's about time we get into abstraction overall abstraction

get into abstraction overall abstraction is the process of hiding implementation

is the process of hiding implementation details and showing only the essential

details and showing only the essential features think of it like this if I'm

features think of it like this if I'm teaching somebody how to drive I'm not

teaching somebody how to drive I'm not going to open up the hood of the car and

going to open up the hood of the car and explain how the engine works I'm instead

explain how the engine works I'm instead going to tell the user that the gas

going to tell the user that the gas pedal is to drive and the brake is to

pedal is to drive and the brake is to stop the car abstraction is the process

stop the car abstraction is the process of hiding implementation details a user

of hiding implementation details a user just needs to know what the gas pedal is

just needs to know what the gas pedal is and what the brake is we can make

and what the brake is we can make classes and methods abstract by using

classes and methods abstract by using this abstract keyword this provides a

this abstract keyword this provides a few benefits abstract classes can't be

few benefits abstract classes can't be instantiated directly abstract classes

instantiated directly abstract classes can also contain abstract methods which

can also contain abstract methods which must be implemented they can also

must be implemented they can also contain concrete methods which are the

contain concrete methods which are the opposite these are real and physical

opposite these are real and physical methods you could say concrete methods

methods you could say concrete methods are inherited so I know that's a lot let

are inherited so I know that's a lot let me give you an example we're going to be

me give you an example we're going to be creating an abstract class that can't be

creating an abstract class that can't be instantiated directly meaning we can't

instantiated directly meaning we can't create any objects from this class in

create any objects from this class in this demonstration we're going to create

this demonstration we're going to create some shape objects shape is going to be

some shape objects shape is going to be the parent then we'll have circle

the parent then we'll have circle triangle and rectangle classes as its

triangle and rectangle classes as its children so we're going to go to new

children so we're going to go to new Java class we will create a shape

Java class we will create a shape class then a class for

rectangle our shape class is going to be abstract we can't create any shape

abstract we can't create any shape objects before the word of class we will

objects before the word of class we will add this keyword of abstract we can't

add this keyword of abstract we can't create any shape objects it's an

create any shape objects it's an abstract class now circle triangle and

abstract class now circle triangle and rectangle are going to extend the shape

rectangle are going to extend the shape class Circle extends shape circles are

class Circle extends shape circles are type of shape same thing applies with

type of shape same thing applies with triangle and

triangle and rectangle let's attempt to create a

rectangle let's attempt to create a shape object shape shape equals new

shape object shape shape equals new shape and we get an error message shape

shape and we get an error message shape is abstract it cannot be

is abstract it cannot be instantiated since shape is an abstract

instantiated since shape is an abstract class we can't create any objects from

class we can't create any objects from this class it adds a little bit of

this class it adds a little bit of security to our program we don't want

security to our program we don't want anybody creating any generic shape

anybody creating any generic shape objects

objects we want them to create a certain kind of

we want them to create a certain kind of shape a circle a triangle or a rectangle

shape a circle a triangle or a rectangle but we can create some circles triangles

but we can create some circles triangles and rectangles so let's do so circle

and rectangles so let's do so circle circle equals new

circle equals new circle triangle

circle triangle triangle equals new

triangle equals new triangle

triangle rectangle

rectangle rectangle equals new rectangle

we can create circle triangle and rectangle objects just not shape because

rectangle objects just not shape because it's an abstract

it's an abstract class that's good though because we

class that's good though because we don't want people creating any shape

don't want people creating any shape objects it's too generic we want a user

objects it's too generic we want a user to pick a certain kind of shape abstract

to pick a certain kind of shape abstract classes can contain abstract methods and

classes can contain abstract methods and concrete methods an abstract method is a

concrete methods an abstract method is a method which must be implemented by its

method which must be implemented by its children within our shape class

children within our shape class we will define an abstract method use

we will define an abstract method use the abstract keyword let's list a return

the abstract keyword let's list a return type of double every child class of the

type of double every child class of the shape class needs an area method I'll

shape class needs an area method I'll add a comment that this is an abstract

add a comment that this is an abstract method

method abstract So within our Circle class we

abstract So within our Circle class we get an error

get an error message Circle must either be declared

message Circle must either be declared abstract or implement the abstract

abstract or implement the abstract method of area circle is going to

method of area circle is going to inherit this abstract method of area

inherit this abstract method of area from its parent of shape we need to

from its parent of shape we need to implement this method so let's do

implement this method so let's do so this is going to be an overridden

so this is going to be an overridden method we need The annotation of

method we need The annotation of override we need to define a method of

override we need to define a method of area but we'll fill it in momentarily

area but we'll fill it in momentarily just for now I'm going to return zero

just for now I'm going to return zero and now that error message goes away

and now that error message goes away since we inherit from the shape class

since we inherit from the shape class and there's an abstract method of area

and there's an abstract method of area we need to implement this method this

we need to implement this method this helps to ensure consistency among the

helps to ensure consistency among the children classes you can see that we're

children classes you can see that we're missing that same method with triangle

missing that same method with triangle and rectangle so why don't we copy this

and rectangle so why don't we copy this code where we override the area method

code where we override the area method and paste

and paste it we'll be filling these in

later going back to our shape class abstract classes can contain abstract

abstract classes can contain abstract methods and concrete methods which are

methods and concrete methods which are kind of the opposite concrete methods

kind of the opposite concrete methods are defined and inherited within an

are defined and inherited within an abstract class let's define a method of

abstract class let's define a method of display this method doesn't return

display this method doesn't return anything the return type is void we'll

anything the return type is void we'll just output the

just output the following this is a shape I'll add a

following this is a shape I'll add a comment that this is a concrete method

comment that this is a concrete method in an abstract class a concrete method

in an abstract class a concrete method is

is inherited within our circle triangle and

inherited within our circle triangle and rectangle classes we don't need to

rectangle classes we don't need to implement it we don't need to override

implement it we don't need to override this method it's

this method it's inherited going back to our main Java

inherited going back to our main Java file if I was to take my circle object

file if I was to take my circle object call the display method we get the

call the display method we get the following

following output this is a shape and that applies

output this is a shape and that applies with triangle and rectangle to triangle.

with triangle and rectangle to triangle. display rectangle.

display this is a shape this is a shape this is a a

this is a a shape this concrete method of display

shape this concrete method of display was inherited from the shape class their

was inherited from the shape class their parent now we'll Define the area methods

parent now we'll Define the area methods area is an abstract method that means

area is an abstract method that means that the children classes have to Define

that the children classes have to Define it to calculate the area of a circle

it to calculate the area of a circle we'll need a radius we'll Define that as

we'll need a radius we'll Define that as an attribute all circles will have a

an attribute all circles will have a radius attribute Double Radius and we'll

radius attribute Double Radius and we'll need a Constructor a circle Constructor

need a Constructor a circle Constructor when we construct a circle object we

when we construct a circle object we have to pass in a double for the

have to pass in a double for the radius this. rius equals the radius we

radius this. rius equals the radius we receive now the formula to calculate the

receive now the formula to calculate the area of a circle will be we're going to

area of a circle will be we're going to return access the math class access the

return access the math class access the constant of Pi from the math class times

constant of Pi from the math class times radius time

radius that's how to calculate the area of a circle

of a circle now for our triangle we need the

now for our triangle we need the following a double for base a double for

following a double for base a double for height we need a

Constructor parameter 1 will be double base parameter 2 will be double

base parameter 2 will be double height this.

height this. base equals

base equals base this do height equals height

base this do height equals height for the area we will

for the area we will return

return 0.5 time base time

0.5 time base time height then we have a

rectangle double length double

length double width we need our Constructor of

rectangle parameter 1 will be double length parameter 2 will be double

length parameter 2 will be double width this do length equals

width this do length equals length this. width equals

length this. width equals width

width return length time width within the area

return length time width within the area method and we're good let's go back to

method and we're good let's go back to our main class we're missing those

our main class we're missing those arguments we have to pass them in for

arguments we have to pass them in for our Circle object let's say the radius

our Circle object let's say the radius is three for the triangle the base and

is three for the triangle the base and height will be 4 and 5 the rectangle the

height will be 4 and 5 the rectangle the length and width will be 6 and

length and width will be 6 and 7 we are going to Output using

7 we are going to Output using system.out.print line take our circle

system.out.print line take our circle called the area

called the area method then do this with triangle and

rectangle here's the area of each of our shapes our Circle our triangle and a

shapes our Circle our triangle and a rectangle so that's the abstract keyword

rectangle so that's the abstract keyword abstraction is the process of hiding

abstraction is the process of hiding implementation details from a user and

implementation details from a user and showing only the essential features

showing only the essential features that's why we've created a shape class

that's why we've created a shape class that's abstract we can't directly create

that's abstract we can't directly create any shape objects we want a user to

any shape objects we want a user to create a certain kind of shape whether

create a certain kind of shape whether it's a circle a triangle or a rectangle

it's a circle a triangle or a rectangle a shape is too generic an abstract class

a shape is too generic an abstract class can contain abstract methods which need

can contain abstract methods which need to be implemented by the children

to be implemented by the children classes or concrete methods which are

classes or concrete methods which are inherited and the children classes will

inherited and the children classes will have access to it all right everybody so

have access to it all right everybody so that is abstraction and the of the

that is abstraction and the of the abstract keyword in Java all right

abstract keyword in Java all right what's going on everybody in this video

what's going on everybody in this video I got to explain interfaces using Java

I got to explain interfaces using Java an interface is very similar to an

an interface is very similar to an abstract class in fact there's a lot of

abstract class in fact there's a lot of overlap where you could use either one

overlap where you could use either one but there's a few key differences an

but there's a few key differences an interface is a blueprint for a class it

interface is a blueprint for a class it specifies a set of abstract methods that

specifies a set of abstract methods that any implementing classes must Define one

any implementing classes must Define one key difference is that by using

key difference is that by using interfaces we can achieve multiple

interfaces we can achieve multiple inheritance like Behavior normally with

inheritance like Behavior normally with inheritance a class can only have a

inheritance a class can only have a single parent but by using interfaces a

single parent but by using interfaces a class can have multiple parents like two

class can have multiple parents like two three or more so in this demonstration

three or more so in this demonstration we're going to create two interfaces

we're going to create two interfaces let's go to file new Java class rather

let's go to file new Java class rather than creating a class we're going to

than creating a class we're going to create an interface we will create an

create an interface we will create an interface of prey and the other for

interface of prey and the other for predator file new Java class

predator file new Java class interface

interface Predator we're going to be declaring

Predator we're going to be declaring some methods but not defining them if a

some methods but not defining them if a class inherits from the prey interface

class inherits from the prey interface they will have to finish defining a

they will have to finish defining a method of flea the return type will be

method of flea the return type will be void if you're considered prey you need

void if you're considered prey you need a flea method to run away if you're a

a flea method to run away if you're a predator you need to define a method to

predator you need to define a method to hunt cuz you're a predator now we'll be

hunt cuz you're a predator now we'll be creating three classes file new Java

creating three classes file new Java class the first class will be rabbit

then fish we'll create a fish class and

Hawk going to our rabbit class rabbits are typically considered prey not

are typically considered prey not Predators unless you count that one

Predators unless you count that one rabbit from Monty Python and the Holy

rabbit from Monty Python and the Holy Grail that's the exception our rabbit

Grail that's the exception our rabbit class is going to

class is going to implements the prey interface we get a

implements the prey interface we get a warning message class rabbit must either

warning message class rabbit must either declare abstract or Implement abstract

declare abstract or Implement abstract method flee since the rabbit class is

method flee since the rabbit class is implementing the prey interface we have

implementing the prey interface we have to finish defining this method that's

to finish defining this method that's declared within the prey interface it's

declared within the prey interface it's kind of like a contract the prey

kind of like a contract the prey interface is telling the rabbit class

interface is telling the rabbit class hey if you're going to implement me you

hey if you're going to implement me you need to Define this method a flea we'll

need to Define this method a flea we'll need to do that in order to create rabid

need to do that in order to create rabid objects we're going to be overwriting

objects we're going to be overwriting this method using the override

this method using the override annotation this method will be flee void

annotation this method will be flee void flee and we'll want to add this axis

flee and we'll want to add this axis modifier of public it's a publicly

modifier of public it's a publicly accessible method in this method we're

accessible method in this method we're going to Output the following let's say

going to Output the following let's say the rabbit is running

the rabbit is running away and that error should go away let's

away and that error should go away let's go back to our main class we'll create a

go back to our main class we'll create a rabbit object and test it rabbit rabbit

rabbit object and test it rabbit rabbit equals new rabbit let's take our rabbit

equals new rabbit let's take our rabbit object have it call the flea

object have it call the flea method and this should

method and this should work yes the rabbit is running away now

work yes the rabbit is running away now let's go to our Hawk class Hawk will

let's go to our Hawk class Hawk will implement the Predator

implement the Predator interface but we have to override this

interface but we have to override this method of hunt because with The Predator

method of hunt because with The Predator interface it's kind of like we're

interface it's kind of like we're signing a contract if Hawk is going to

signing a contract if Hawk is going to implement the Predator interface then we

implement the Predator interface then we have to finish defining this method we

have to finish defining this method we will add the at override

will add the at override annotation and Define this method and

annotation and Define this method and then again we do need an axis modifier

then again we do need an axis modifier we'll pick

we'll pick public let's output the

public let's output the following the hawk is

following the hawk is hunting let's create a hawk

hunting let's create a hawk object Hawk Hawk equals New

object Hawk Hawk equals New Hawk our rabbit is fleeing let's take

Hawk our rabbit is fleeing let's take our Hawk object use the hunt method

okay we have the rabbit is running away the hawk is

the hawk is hunting now rabbits don't have a hunt

hunting now rabbits don't have a hunt method and Hawks don't have a flea

method now one key difference with interfaces compared to abstract classes

interfaces compared to abstract classes is that you can Implement more than one

is that you can Implement more than one interface so fish they eat smaller fish

interface so fish they eat smaller fish and they flee larger fish they could be

and they flee larger fish they could be considered both prey and

considered both prey and predators we will implement two

predators we will implement two interfaces Implement prey comma Predator

interfaces Implement prey comma Predator then we need both of these methods we

then we need both of these methods we have to finish defining both again we're

have to finish defining both again we're going to use the at override

going to use the at override annotation we will create a publicly

annotation we will create a publicly accessible method a flea where we will

accessible method a flea where we will print the fish is

print the fish is swimming away and we need a hunt method

too add the at override annotation this is a public method of hunt where we will

is a public method of hunt where we will print the fish is hunting let's say all

print the fish is hunting let's say all right let's test it we will create a

right let's test it we will create a fish object fish fish equals new

fish object fish fish equals new fish our fish can

fish our fish can flee and our fish can

hunt the fish is swimming away the fish is hunting our fish object implements

is hunting our fish object implements both the prey and Predator interfaces it

both the prey and Predator interfaces it has to Define these two methods so

has to Define these two methods so that's one key difference with

that's one key difference with interfaces compared to abstract classes

interfaces compared to abstract classes a class can inherit more than one

a class can inherit more than one interface normally with inheritance you

interface normally with inheritance you can only have one parent but this is a

can only have one parent but this is a way around that using interfaces fish

way around that using interfaces fish are considered both prey and predators

are considered both prey and predators all right everybody so that is a quick

all right everybody so that is a quick introduction to interfaces an interface

introduction to interfaces an interface is a blueprint for a class that's

is a blueprint for a class that's specifies a set of abstract methods that

specifies a set of abstract methods that implementing classes must Define and it

implementing classes must Define and it supports multiple inheritance like

supports multiple inheritance like Behavior there's a lot of overlap where

Behavior there's a lot of overlap where you can use abstract classes or

you can use abstract classes or interfaces you should be familiar with

interfaces you should be familiar with both and well everybody that's a quick

both and well everybody that's a quick introduction to interfaces using Java so

introduction to interfaces using Java so yeah it's about time I explain

yeah it's about time I explain polymorphism using Java polymorphism is

polymorphism using Java polymorphism is a Greek word poly means many morph means

a Greek word poly means many morph means shape together you get the concept of

shape together you get the concept of many shapes or forms it's a general

many shapes or forms it's a general programming concept objects can identify

programming concept objects can identify as other objects objects of different

as other objects objects of different types objects can be treated as objects

types objects can be treated as objects of a common super Class A dog identifies

of a common super Class A dog identifies as a dog but it can also identify as an

as a dog but it can also identify as an animal it can also identify as an

animal it can also identify as an organism it can also identify as an

organism it can also identify as an object it can identify as more than one

object it can identify as more than one thing in this topic we're going to

thing in this topic we're going to create a few vehicle objects let's

create a few vehicle objects let's create a few classes file new Java class

create a few classes file new Java class we will create a super class of vehicle

we will create a super class of vehicle iicle this class doesn't have to be

iicle this class doesn't have to be abstract but let's make it abstract we

abstract but let's make it abstract we can't create any vehicle

can't create any vehicle objects we will declare an abstract

objects we will declare an abstract method that doesn't return anything the

method that doesn't return anything the return type is void if you're a vehicle

return type is void if you're a vehicle you need a go method so what we're going

you need a go method so what we're going to be doing is creating a few different

to be doing is creating a few different types of vehicles a car bike and boat

types of vehicles a car bike and boat class which will inherit from the class

class which will inherit from the class of vehicle so let's create these classes

of vehicle so let's create these classes file new Java class we will create a car

file new Java class we will create a car class that extends the vehicle class but

class that extends the vehicle class but there is an abstract method of go that

there is an abstract method of go that we need to

we need to Define we will use the at override

Define we will use the at override annotation the method will be return

annotation the method will be return type of void go all we'll do is output

type of void go all we'll do is output you drive the car all right let's do

you drive the car all right let's do this with a few other classes I'll just

this with a few other classes I'll just copy this method because we'll reuse it

copy this method because we'll reuse it we'll create a bike class

we'll create a bike class bike bike extends

bike bike extends vehicle and we need that method of go

vehicle and we need that method of go you ride the

you ride the bike and a boat class file new Java

bike and a boat class file new Java class

class Boat Boat extends

that is good enough for now going back to our main Java file let's create these

to our main Java file let's create these objects starting with our car car car

objects starting with our car car car equals new

equals new car bike bike equals new

car bike bike equals new bike Boat Boat equals new

boat each of these objects has a go method for example let's have our car

method for example let's have our car object use its go method followed by

object use its go method followed by bike bike Dogo method and Boat Boat Dogo

bike bike Dogo method and Boat Boat Dogo method you drive the car you ride the

method you drive the car you ride the bike you sail the boat so let's say we

bike you sail the boat so let's say we would like to have a

would like to have a race we're going to place all of these

race we're going to place all of these objects within an array our car bike and

objects within an array our car bike and boat objects so what should the data

boat objects so what should the data type of the array be let's attempt to

type of the array be let's attempt to create an array of car objects and place

create an array of car objects and place our bike and boat objects within that

our bike and boat objects within that array and we'll just see what happens

array and we'll just see what happens exactly for learning purposes I will

exactly for learning purposes I will create an array of

create an array of cars the data type is car it's an array

cars the data type is car it's an array named cars equals curly braces let's

named cars equals curly braces let's stick our car bike and boat objects

stick our car bike and boat objects within here we're already getting a few

within here we're already getting a few error

messages incompatible types bike cannot be converted to car bikes and boats

be converted to car bikes and boats don't identify as cars cars identify as

don't identify as cars cars identify as cars s that's one of the shapes that

cars s that's one of the shapes that bikes and boats don't have they don't

bikes and boats don't have they don't identify as cars if this were an array

identify as cars if this were an array of

of bikes bike bikes equals R array of

bikes bike bikes equals R array of objects well then we have another a

objects well then we have another a message car cannot be converted to a

message car cannot be converted to a bike and you can assume the same thing

bike and you can assume the same thing applies with

applies with boats cars and bikes don't identify as

boats cars and bikes don't identify as boats what we could do is declare our

boats what we could do is declare our array of what they have in common well

array of what they have in common well our car bike and boat they all extend

our car bike and boat they all extend the vehicle class you could say they

the vehicle class you could say they also identify as Vehicles we're going to

also identify as Vehicles we're going to change the data type of our array to

change the data type of our array to hold Vehicles we have an array of

hold Vehicles we have an array of vehicle

vehicle objects and then let's change our array

objects and then let's change our array name to be Vehicles cars identifies cars

name to be Vehicles cars identifies cars but also Vehicles bikes identifies bikes

but also Vehicles bikes identifies bikes but also Vehicles boats identify as

but also Vehicles boats identify as boats but also Vehicles that's the one

boats but also Vehicles that's the one thing they have in common they're all

thing they have in common they're all extending the vehicle super class

extending the vehicle super class they're also considered Vehicles that's

they're also considered Vehicles that's another one of their forms they shapes

another one of their forms they shapes for every object within this array I

for every object within this array I would like to have each object use its

would like to have each object use its go method like we're

go method like we're racing well what we could do is use a

racing well what we could do is use a for each

Loop what's the data type of the array well it's vehicle we have an array of

well it's vehicle we have an array of vehicles we will give a nickname of each

vehicles we will give a nickname of each vehicle

vehicle as vehicle in my array of

as vehicle in my array of vehicles for every vehicle in this array

vehicles for every vehicle in this array of vehicles let's take each

of vehicles let's take each vehicle call the go method take every

vehicle call the go method take every vehicle object call its go method here's

vehicle object call its go method here's the result you drive the car you ride

the result you drive the car you ride the bike you sail the

the bike you sail the boat oh and another thing I'm forgetting

boat oh and another thing I'm forgetting polymorphism can also be achieved

polymorphism can also be achieved through using interfaces let's delete

through using interfaces let's delete our vehicle

class we'll create a new Java class this will be an interface a

vehicle rather than extending the vehicle class we will implements the

vehicle class we will implements the vehicle

interface we will declare a method of go that doesn't return

that doesn't return anything these methods do need an access

anything these methods do need an access modifier let's just say

public so polymorphism can be achieved this way too through using interfaces if

this way too through using interfaces if you prefer interfaces in summary

you prefer interfaces in summary polymorphism means many shapes it's

polymorphism means many shapes it's where objects can identify as themselves

where objects can identify as themselves but also other objects objects can be

but also other objects objects can be treated as objects of a common super

treated as objects of a common super class and well everybody that is an

class and well everybody that is an introduction to polymorphism using jav

introduction to polymorphism using jav Ava what's going on people today I got

Ava what's going on people today I got to explain a runtime polymorphism also

to explain a runtime polymorphism also known as Dynamic polymorphism how I

known as Dynamic polymorphism how I would explain it in a single sentence is

would explain it in a single sentence is when the method that gets executed is

when the method that gets executed is decided at runtime based on the actual

decided at runtime based on the actual type of the object in this demonstration

type of the object in this demonstration a user is going to pick a type of animal

a user is going to pick a type of animal they want as a pet a dog or a cat but

they want as a pet a dog or a cat but that's going to be determined at runtime

that's going to be determined at runtime after the program is already running

after the program is already running we'll create a total of three classes

we'll create a total of three classes first we'll create an animal class which

first we'll create an animal class which will be a parent class we will create a

will be a parent class we will create a class of animal we might as well make

class of animal we might as well make this an abstract class for good practice

this an abstract class for good practice we don't want anybody creating any

we don't want anybody creating any animal objects we will have an abstract

animal objects we will have an abstract method the return type is void this

method the return type is void this method will be speak when an animal

method will be speak when an animal speaks they'll say something

speaks they'll say something unique we'll create a dog class file new

unique we'll create a dog class file new Java class we will create a class of dog

Java class we will create a class of dog that

that extends the animal class but we do need

extends the animal class but we do need a speak method we will use method

a speak method we will use method overwriting the return type is void with

overwriting the return type is void with our speak

our speak method we will output the

method we will output the following the dog goes woof all right

following the dog goes woof all right then we need a cat class file new Java

then we need a cat class file new Java class we will create a class of

class we will create a class of cat cat extends

cat cat extends animal and we'll just copy the speak

animal and we'll just copy the speak method just to save a little bit of

method just to save a little bit of time when the cat speaks we'll output

time when the cat speaks we'll output the cat goes meow that's good enough for

the cat goes meow that's good enough for this

this example since animal is an abstract

example since animal is an abstract class we can't create any animal objects

class we can't create any animal objects I'll attempt to do so animal animal

I'll attempt to do so animal animal equals new

equals new animal and we get an error message

animal and we get an error message animal is abstract can be instantiated

animal is abstract can be instantiated that's good though animals are too

that's good though animals are too generic we would rather have a user

generic we would rather have a user create a certain kind of animal either a

create a certain kind of animal either a dog or a cat in this demonstration we're

dog or a cat in this demonstration we're going to have a user pick if they want a

going to have a user pick if they want a dog or a cat but we don't know which one

dog or a cat but we don't know which one they're going to pick so why don't we do

they're going to pick so why don't we do this let's declare an animal object but

this let's declare an animal object but not instantiate it we will assign our

not instantiate it we will assign our animal equal to a new dog or a new cat

animal equal to a new dog or a new cat based on the user input so animal animal

based on the user input so animal animal this will either be animal equals a new

this will either be animal equals a new dog or animal equals a new cat based on

dog or animal equals a new cat based on the user

the user input we will declare an object that's

input we will declare an object that's at least an animal we'll accept some

at least an animal we'll accept some user input we'll need a scanner scanner

user input we'll need a scanner scanner scanner equals new

scanner equals new scanner we will pass in

scanner we will pass in system.in and import this class

system.in and import this class java.util.scanner

java.util.scanner we'll need a prompt

would you like a dog or a cat we'll say 1 equals dog 2 equals

cat we'll say 1 equals dog 2 equals cat I'll use print rather than print

cat I'll use print rather than print line because I like the input on the

line because I like the input on the same line let's declare a variable of

same line let's declare a variable of choice this will be an integer we'll use

choice this will be an integer we'll use our scanner called the next int method

our scanner called the next int method and then we'll do the

and then we'll do the following we'll examine if our choice

following we'll examine if our choice variable is equal to one if it is we'll

variable is equal to one if it is we'll finish instantiating our animal object

finish instantiating our animal object but we'll assign it to be a new dog

but we'll assign it to be a new dog object then we will have our animal use

object then we will have our animal use its speak

its speak method so if it's a dog it should go

choice is equal to two then we will instantiate our animal object as a new C

instantiate our animal object as a new C and have our animal use its speak

method you could add an else Clause but it's not really

it's not really necessary this is good enough for

necessary this is good enough for now before running the program we don't

now before running the program we don't know what kind of animal we're going to

know what kind of animal we're going to create it's either going to be a dog or

create it's either going to be a dog or a cat

if I select one we get a dog the dog goes

goes woof if I select two we get a cat the

woof if I select two we get a cat the cat goes meow the actual method that we

cat goes meow the actual method that we call is determined at runtime after the

call is determined at runtime after the program is already

program is already running before we run the program we

running before we run the program we know that we're going to use a speak

know that we're going to use a speak method we're just not sure which one so

method we're just not sure which one so that's runtime polymorphism it's when

that's runtime polymorphism it's when the method that gets executed is decided

the method that gets executed is decided at runtime based on the actual type of

at runtime based on the actual type of object that we create and well everybody

object that we create and well everybody that is an introduction to runtime

that is an introduction to runtime polymorphism using

polymorphism using Java all right everybody today I'm going

Java all right everybody today I'm going to be explaining getter and Setter

to be explaining getter and Setter methods using Java getter and Setter

methods using Java getter and Setter methods help protect object data and

methods help protect object data and they add rules for accessing or

they add rules for accessing or modifying that data here's a

modifying that data here's a demonstration we're going to create a

demonstration we're going to create a class of car file new class we will

class of car file new class we will create a car

create a car Class A few attributes that cars could

Class A few attributes that cars could have include a string of model A String

have include a string of model A String of color and an INT let's say price then

of color and an INT let's say price then we'll need a

we'll need a Constructor we'll have three

Constructor we'll have three parameters a string of model A String of

parameters a string of model A String of color and an inch of price we will

color and an inch of price we will assign this do

assign this do model equals

model equals model this do color equals color

model this do color equals color this St price equals price let's

this St price equals price let's construct a car

object car car equals new car pick a model a year and a price I've

car pick a model a year and a price I've already used red Mustangs for too many

already used red Mustangs for too many examples I'll pick something else let's

examples I'll pick something else let's say a

say a charger that is yellow and the price

charger that is yellow and the price will be

will be $10,000 but I don't know if that's good

$10,000 but I don't know if that's good or not we don't even know the year of

or not we don't even know the year of the car anyways so we have our car

the car anyways so we have our car object and then let's output these

object and then let's output these attributes just to test them car. color

attributes just to test them car. color I'll add a space character to plus car.

I'll add a space character to plus car. model plus a space

model plus a space character plus car. price I'm

character plus car. price I'm intentionally not adding a unit of

intentionally not adding a unit of currency so here's our

currency so here's our car I have a yellow charger and the

car I have a yellow charger and the price is 10,000 10,000 of a unit of

price is 10,000 10,000 of a unit of currency that you choose but that's not

currency that you choose but that's not important

important with our car object its attributes are

with our car object its attributes are publicly accessible meaning we can view

publicly accessible meaning we can view and change them

and change them easily to demonstrate let's say that the

easily to demonstrate let's say that the model of our car is now a

Corvette we have a yellow Corvette that is

is $10,000 we don't want the model of our

$10,000 we don't want the model of our car to magically become a Corvette once

car to magically become a Corvette once we assign its model to be charger we

we assign its model to be charger we don't want it to change what we could do

don't want it to change what we could do when to declaring these attributes is

when to declaring these attributes is add this access modifier of private

add this access modifier of private preceding the data type private string

preceding the data type private string model private string color private and

model private string color private and price we can't access them and let's

price we can't access them and let's test that you can see that the font

test that you can see that the font color already changed to

color already changed to Red I will attempt to print the car's

Red I will attempt to print the car's color model and

price color has private access and car model has private ACC access in car and

model has private ACC access in car and price has private access in

price has private access in car since these attributes are private

car since these attributes are private we can't normally access them outside of

we can't normally access them outside of the car class but there is a way around

the car class but there is a way around that and that is by using getter and

that and that is by using getter and Setter methods getter methods make a

Setter methods getter methods make a field readable Setter methods make a

field readable Setter methods make a field writable use get to read set to

field writable use get to read set to write we'll set up some getter methods

write we'll set up some getter methods first I would like the car's color model

first I would like the car's color model and price

and price here's how we can do that within the car

here's how we can do that within the car class we will create a method we'll

class we will create a method we'll start with the model the return type

start with the model the return type will be string because our model is a

will be string because our model is a string data type we'll create a getter

string data type we'll create a getter method following this naming convention

method following this naming convention get then the name of the attribute

get then the name of the attribute model all we're going to do is return

model all we're going to do is return this.

this. model and then we'll do this with the

model and then we'll do this with the color and the price and I'll just copy

color and the price and I'll just copy this method because I'm I'm feeling a

this method because I'm I'm feeling a little lazy we have get

little lazy we have get model get color return this.

model get color return this. color and get

color and get price return this.

price return this. price oh and this returns an integer not

price oh and this returns an integer not a string because our price is an integer

a string because our price is an integer let's go back to our main Java file

let's go back to our main Java file rather than accessing these attributes

rather than accessing these attributes directly because we can't we're going to

directly because we can't we're going to call these getter methods get model if

call these getter methods get model if you need the model get color if you need

you need the model get color if you need the color get price if you need the

the color get price if you need the price replace car. color with car do get

price replace car. color with car do get color and this is a method car. getet

color and this is a method car. getet model and car. getet price and that

model and car. getet price and that should

should work yep we can now read those

work yep we can now read those attributes we have a yellow charger and

attributes we have a yellow charger and the price is

the price is 10,000 another thing you can do too with

10,000 another thing you can do too with getter methods you can add additional

getter methods you can add additional logic so with our get price method let's

logic so with our get price method let's instead return a string we will return a

instead return a string we will return a unit of currency I'll pick American

unit of currency I'll pick American dollars plus the price let's see how

dollars plus the price let's see how that

that changes again we are calling the get

changes again we are calling the get price

$110,000 getter methods make a field readable and you can add additional

readable and you can add additional logic when retrieving one of these

logic when retrieving one of these attributes and in this demonstration I

attributes and in this demonstration I just added a dollar sign just to keep it

just added a dollar sign just to keep it simple then we have Setter methods

simple then we have Setter methods Setter methods make a field writable

Setter methods make a field writable going to our car class we have model

going to our car class we have model color and price I don't want the model

color and price I don't want the model attribute to be writable once we've

attribute to be writable once we've declared the model of our car we don't

declared the model of our car we don't want to change it our charger can't

want to change it our charger can't magically become a Corvette even though

magically become a Corvette even though that'd be pretty cool but the color you

that'd be pretty cool but the color you could change you can paint your car and

could change you can paint your car and the price you can sell your car for a

the price you can sell your car for a different price we'll declare Setter

different price we'll declare Setter methods for our color and price but not

methods for our color and price but not the model because we don't want this

the model because we don't want this attribute to be

attribute to be writable so let's scroll down to the

writable so let's scroll down to the bottom following a similar pattern we're

bottom following a similar pattern we're going to create a method the return type

going to create a method the return type is void this will be set

is void this will be set color we have one parameter a string of

color we have one parameter a string of color we will assign this do color equal

color we will assign this do color equal to the new color that we

to the new color that we receive we'll do this with our price

receive we'll do this with our price too void set

too void set price we'll have one parameter and int

price we'll have one parameter and int of

of price this. price equals price the new

price this. price equals price the new price that we receive okay let's test

price that we receive okay let's test these

things I'll attempt to access our color directly car. color equals I don't know

directly car. color equals I don't know blue that's the first thing that came to

blue that's the first thing that came to mind and car. price equals you know what

mind and car. price equals you know what the car's on sale it's

the car's on sale it's $5,000 well I can't change these we

$5,000 well I can't change these we still have that red text for color and

still have that red text for color and price because the color and price

price because the color and price attributes are still

attributes are still private instead we're going to call

private instead we're going to call these Setter

these Setter methods we will set the color and then

methods we will set the color and then pass in the new

pass in the new color rather than assign it directly set

color rather than assign it directly set color pass in a new

color pass in a new color set price passing a new price

color set price passing a new price 5,000 then using our Getters we should

5,000 then using our Getters we should be able to print these

be able to print these attributes yes we now have a blue

attributes yes we now have a blue charger and the price is

charger and the price is $5,000 we don't have a Setter method set

$5,000 we don't have a Setter method set up for the model that's good though we

up for the model that's good though we don't want the model to

don't want the model to change we only have set

change we only have set and set price if I attempt to access a

and set price if I attempt to access a set model

set model method we shouldn't be able to change

it because we never declared a set model method it doesn't exist but if you did

method it doesn't exist but if you did want to change the model if you want

want to change the model if you want this attribute to be writable well then

this attribute to be writable well then you could add a Setter

you could add a Setter method void set

method void set model we'll pass in a string for the new

model we'll pass in a string for the new model this model equals

model this model equals model and then you could change

model and then you could change it we have a blue corvet for $5,000

it we have a blue corvet for $5,000 which is really

which is really cheap but you know what I don't want the

cheap but you know what I don't want the model to be writable just

model to be writable just readable if you don't want an attribute

readable if you don't want an attribute to be writable when you declare it you

to be writable when you declare it you can also add this keyword a final that

can also add this keyword a final that adds an extra security

measure one last thing we should do with the price let's add some additional

the price let's add some additional logic so with our price let's do the

logic so with our price let's do the following let's add a

following let's add a check if our price is less than zero

check if our price is less than zero then let's output the

then let's output the following price can't be less than

following price can't be less than zero else if everything checks out if

zero else if everything checks out if our price is zero or above then we'll

our price is zero or above then we'll assign this do price equals the price

assign this do price equals the price that we receive as an argument Let's

that we receive as an argument Let's test it

test it I'll change the color of my car to be

I'll change the color of my car to be blue but the price is going to

be100 we get that message price can't be less than zero the color changed but not

less than zero the color changed but not the price it stayed the same at

the price it stayed the same at $10,000 so those are getter and Setter

$10,000 so those are getter and Setter methods they help protect object data

methods they help protect object data and add rules for accessing or modifying

and add rules for accessing or modifying that data getter methods make a field

that data getter methods make a field readable Setter methods make a a field

readable Setter methods make a a field writable depending on your object's

writable depending on your object's attributes you may want some to be

attributes you may want some to be readable or writable or both it's up to

readable or writable or both it's up to you and well everybody those are getter

you and well everybody those are getter and Setter methods using Java all right

and Setter methods using Java all right let's do this today I got to talk about

let's do this today I got to talk about aggregation in programming aggregation

aggregation in programming aggregation represents a has a relationship between

represents a has a relationship between objects one object contains another

objects one object contains another object as part of its structure but the

object as part of its structure but the contained object or objects can exist

contained object or objects can exist independently B basically speaking an

independently B basically speaking an object can contain another object but

object can contain another object but those objects can exist independently

those objects can exist independently what we'll do for this demonstration is

what we'll do for this demonstration is create some book objects then we'll

create some book objects then we'll create a library object to contain the

create a library object to contain the book objects the books and the library

book objects the books and the library can exist independently that's

can exist independently that's aggregation the library object will have

aggregation the library object will have book objects we'll create a new class of

book objects we'll create a new class of book file new class

book file new class book and a class for Library file new

book and a class for Library file new class

class Library let's design our book

Library let's design our book objects let's say that books have a

objects let's say that books have a string of title and an integer for Pages

string of title and an integer for Pages you could include an author too if you

you could include an author too if you would like but I don't want this example

would like but I don't want this example to be too big we'll need a Constructor

to be too big we'll need a Constructor for our book

for our book objects we'll set up the parameters we

objects we'll set up the parameters we need a string of title and an integer

need a string of title and an integer for

for Pages this. tile equals title

Pages this. tile equals title this. Pages equals Pages if you would

this. Pages equals Pages if you would like you can set these attributes to be

like you can set these attributes to be private but that might be overkill for

private but that might be overkill for this lesson why don't we create a method

this lesson why don't we create a method to display the book's info this method

to display the book's info this method will return a string we'll Define a

will return a string we'll Define a method to display info we will display

method to display info we will display the info of this book Let's return the

the info of this book Let's return the following let's return this.

following let's return this. tile plus a space character

tile plus a space character plus this.

plus this. pages and a string of the word

pages and I think I'm going to enclose the number of pages within a set of

the number of pages within a set of parenthesis you can also use a print F

parenthesis you can also use a print F statement if that's easier for you but I

statement if that's easier for you but I want to try and keep this beginner

want to try and keep this beginner friendly okay that's good enough for the

friendly okay that's good enough for the book class let's create a few book

book class let's create a few book objects we'll start with book one book

objects we'll start with book one book book one equals a new book but to

book one equals a new book but to construct a book we have to pass in at

construct a book we have to pass in at least the following a title and a number

least the following a title and a number of pages so I've picked out a few books

of pages so I've picked out a few books already feel free to choose your own if

already feel free to choose your own if you would rather choose different books

you would rather choose different books for the first book that I'll pick I will

for the first book that I'll pick I will pick the Fellowship of the Ring this

pick the Fellowship of the Ring this will be all one

will be all one string and the number of pages at least

string and the number of pages at least according to wekipedia is

according to wekipedia is 423 then we'll create another book

423 then we'll create another book another book object this will be book

another book object this will be book two book two will be the two towers the

two book two will be the two towers the number of pages will be

number of pages will be 352 and then book

352 and then book three book three will be the Return of

three book three will be the Return of the

the King the number of pages will be

King the number of pages will be 416 all right we have our independent

416 all right we have our independent book objects then what we'll do is stick

book objects then what we'll do is stick them all within an array we'll create an

them all within an array we'll create an array of book objects named books equals

array of book objects named books equals then within a set of curly braces we can

then within a set of curly braces we can place our book objects within here book

place our book objects within here book one book two book three we have an array

one book two book three we have an array of book objects before moving on let's

of book objects before moving on let's test the display info method of each of

test the display info method of each of these books so we'll need a print

these books so we'll need a print statement book one. display

statement book one. display info so we should get book one The

info so we should get book one The Fellowship of the Ring 423 Pages I'm

Fellowship of the Ring 423 Pages I'm just going to make one

just going to make one change I'll put the right parentheses at

change I'll put the right parentheses at the

end that's better let's display book

better let's display book two the two towers 352

two the two towers 352 Pages book

Pages book three the Return of the King 46

three the Return of the King 46 Pages you could also Loop through this

Pages you could also Loop through this array using an enhanced for for

array using an enhanced for for Loop the data type of each element in my

Loop the data type of each element in my array is book for every book in my array

array is book for every book in my array of

of books will print take each book call the

books will print take each book call the display info

method and here's all the books that I have in my array The Fellowship of the

have in my array The Fellowship of the Ring The Two Towers The Return of the

Ring The Two Towers The Return of the King and we can delete this for Loop we

King and we can delete this for Loop we no longer need it

no longer need it now we're going to create a library

now we're going to create a library object our library object will contain

object our library object will contain our array of book objects because

our array of book objects because libraries contain books going to our

libraries contain books going to our library

library class what should libraries have let's

class what should libraries have let's say that our library should have a name

say that our library should have a name what's the name of the library maybe a

what's the name of the library maybe a year in which the library was

year in which the library was established in year and libraries should

established in year and libraries should contain book objects we will create an

contain book objects we will create an array of book objects named

array of book objects named books we'll need to instructor for the

books we'll need to instructor for the library

library class we'll need the following a string

class we'll need the following a string for the name of the

for the name of the library an integer for the year of the

library an integer for the year of the library when was the library built and

library when was the library built and an array of book

an array of book objects this St name equals

objects this St name equals name this doe equals

name this doe equals year this. books equals the books that

year this. books equals the books that we receive this array

we receive this array all right going back to our main Java

all right going back to our main Java file this is where aggregation is going

file this is where aggregation is going to come

to come in we will create a library

in we will create a library object

object library

library library equals new

library equals new library but we have to pass in the

library but we have to pass in the following as arguments to the

following as arguments to the Constructor a name for the library a

Constructor a name for the library a year for the library and an array of

year for the library and an array of book

book objects so for the library I'm going to

objects so for the library I'm going to say the NYC the New York

say the NYC the New York City public

City public library after a quick Google search this

library after a quick Google search this library was built in the year

library was built in the year 1897 then we also need an array of book

1897 then we also need an array of book objects I will pass in my array of book

objects I will pass in my array of book objects named

objects named books this is

books this is aggregation our library object has book

aggregation our library object has book objects within the library class let's

objects within the library class let's also create a display info method for

also create a display info method for the library we'll make it a little bit

the library we'll make it a little bit different this method won't return

different this method won't return anything let's say the return type is

anything let's say the return type is void we'll name this method display info

void we'll name this method display info we'll display the following information

we'll display the following information about this Library let's output the

about this Library let's output the following

following the this.e of the

the this.e of the library plus a space

library plus a space character plus

character plus this.name you can also also use a printf

this.name you can also also use a printf statement if you would prefer to use

statement if you would prefer to use that I'm trying to keep this as beginner

that I'm trying to keep this as beginner friendly as possible so let's test

friendly as possible so let's test this we will take our library object

this we will take our library object call it display info

method the 1897 New York City public

1897 New York City public library then within this method of

library then within this method of display info for the library let's also

display info for the library let's also list all the books that it has this

list all the books that it has this Library

Library has aggregated a whole bunch of book

has aggregated a whole bunch of book objects so then we can display them or

objects so then we can display them or use them for something let's output the

use them for something let's output the following let's output

following let's output books

books available then we'll use an enhanced for

available then we'll use an enhanced for Loop the data type of what we're

Loop the data type of what we're iterating through is book objects for

iterating through is book objects for every book in my array of books take

every book in my array of books take each book call the books display in

method and then we do have to print it using a print line statement because

using a print line statement because this method returns a

this method returns a string there we go let's test

string there we go let's test it so after calling the display info

it so after calling the display info method of the

method of the library we should display the

library we should display the information of the library including its

information of the library including its books the 1897 New York City public

books the 1897 New York City public library and we display the books

library and we display the books available which are the array of books

available which are the array of books that we have created

that we have created so that's aggregation it represents a

so that's aggregation it represents a has a relationship between objects our

has a relationship between objects our library object has book objects within

library object has book objects within it there's another similar concept

it there's another similar concept called composition with aggregation if

called composition with aggregation if you were to delete this Library class

you were to delete this Library class for example I'll delete

for example I'll delete it well these book objects can exist

it well these book objects can exist independently outside of the library the

independently outside of the library the books aren't built into the library so

books aren't built into the library so they can exist independently which is a

they can exist independently which is a key compared to composition which is the

key compared to composition which is the next topic we'll cover and well

next topic we'll cover and well everybody that is aggregation using Java

everybody that is aggregation using Java hey everybody in this video I'm going to

hey everybody in this video I'm going to explain composition to you in

explain composition to you in programming composition represents a

programming composition represents a part of relationship between objects for

part of relationship between objects for example an engine is part of a car an

example an engine is part of a car an object can be part of another object

object can be part of another object this allows for complex objects to be

this allows for complex objects to be constructed from smaller objects in this

constructed from smaller objects in this demonstration we're going to create a

demonstration we're going to create a car object

car object the car object is composed of an engine

the car object is composed of an engine object we will create a class of car and

object we will create a class of car and a class of

engine we'll begin with our class of car what sorts of attributes should cars

what sorts of attributes should cars have let's say a string of

have let's say a string of model an INT of year and an engine

model an INT of year and an engine object engine engine

object engine engine we'll need a

we'll need a Constructor we'll pass in a string for

Constructor we'll pass in a string for the

the model an INT for the

model an INT for the year now for the engine we're not going

year now for the engine we're not going to be passing in an engine object let's

to be passing in an engine object let's say that when we construct a car object

say that when we construct a car object we have to pass in a string for the

we have to pass in a string for the engine

engine type is it an inline engine is it a V6

type is it an inline engine is it a V6 that sort of thing we will assign this

that sort of thing we will assign this St model equals the model that we

St model equals the model that we receive

receive this. year equals the year that we

this. year equals the year that we receive now with our engine this. engine

receive now with our engine this. engine we're going to call the Constructor for

we're going to call the Constructor for a new engine

a new engine object and then we can pass in our

object and then we can pass in our engine

engine type but we still however have to set up

type but we still however have to set up the Constructor for our engine class

the Constructor for our engine class when constructing a car object we will

when constructing a car object we will also be constructing a new engine object

also be constructing a new engine object so let's go to our engine

so let's go to our engine class let's say that engine

class let's say that engine have a

have a string of type you could say engine type

string of type you could say engine type but that would be redundant I would say

but that would be redundant I would say let's just say type then we need a

let's just say type then we need a Constructor for our engine class we will

Constructor for our engine class we will need a string of type to pass

need a string of type to pass in this.type equals

in this.type equals type so going back to our car class when

type so going back to our car class when we pass in a string for the engine type

we pass in a string for the engine type you could say that this is

you could say that this is type this term is kind of ambiguous

type this term is kind of ambiguous though because a user is going to think

though because a user is going to think that the type is for the car type rather

that the type is for the car type rather than the engine type so when you pass

than the engine type so when you pass arguments your parameter names can be

arguments your parameter names can be different from the argument names that

different from the argument names that you pass in we simply rename them when

you pass in we simply rename them when this Constructor receives that argument

this Constructor receives that argument but type refers to the engine type all

but type refers to the engine type all right so this is a basic demonstration

right so this is a basic demonstration of composition now we'll construct a car

of composition now we'll construct a car object car car equals new

object car car equals new car and then we have to pass in the

car and then we have to pass in the following a string for the model an inch

following a string for the model an inch for the year and a string for the engine

for the year and a string for the engine type pick a card that you like this time

type pick a card that you like this time I will pick a

I will pick a Corvette the year will be

Corvette the year will be 20125 and for the engine I will pick a

20125 and for the engine I will pick a V8

V8 engine then let's see if we have these

engine then let's see if we have these details I'm going to Output my car

details I'm going to Output my car objects model and these attributes I did

objects model and these attributes I did not set to private but you can set them

not set to private but you can set them to private and use Getters and Setters

to private and use Getters and Setters if you would like so we have

if you would like so we have model

object here's what we have we have our model Corvette year 2025 now for the

model Corvette year 2025 now for the engine our engine is an object it's a

engine our engine is an object it's a reference data type so if you you output

reference data type so if you you output it directly you're given a hash ID to

it directly you're given a hash ID to represent that engine object so if we

represent that engine object so if we need the type of engine we're going to

need the type of engine we're going to access our engine object then get the

access our engine object then get the type so following our engine object we

type so following our engine object we will use that access modifier that

will use that access modifier that dot then access the type the

dot then access the type the attribute so the engine type is a

attribute so the engine type is a V8 so it's like we have an object that's

V8 so it's like we have an object that's composed with another object our n

composed with another object our n is part of our car you know what let's

is part of our car you know what let's create a method for the engine we'll

create a method for the engine we'll create a start

create a start method void

method void start we'll output the following let's

start we'll output the following let's say using a print line

say using a print line statement you start

statement you start the plus this. type meaning type of the

the plus this. type meaning type of the engine plus the word engine then going

engine plus the word engine then going to our car class let's create a start

to our car class let's create a start method for the car class

method for the car class void

void start when we start the car we also

start when we start the car we also start the engine let's take this.

start the engine let's take this. engine call it start

engine call it start method and then we can output something

method and then we can output something else too if we would like let's

else too if we would like let's output the plus this do

output the plus this do model plus the words is

model plus the words is running now if we start the car let's

running now if we start the car let's take our car call it start

take our car call it start method and we should get the following

method and we should get the following you start the V8 engine the Corvette is

you start the V8 engine the Corvette is running now a key difference with

running now a key difference with composition is that if we delete our car

composition is that if we delete our car object that should also delete our

object that should also delete our engine cuz our engine is part of our car

engine cuz our engine is part of our car so to demonstrate that I'm going to

so to demonstrate that I'm going to delete our car object

engine all right everybody that is composition it represents a part of

composition it represents a part of relationship between objects for example

relationship between objects for example an engine is part of a car this allows

an engine is part of a car this allows for complex objects to be constructed

for complex objects to be constructed from smaller objects and well everybody

from smaller objects and well everybody that is composition using Java well look

that is composition using Java well look who showed up today I got to talk about

who showed up today I got to talk about rapper classes rapper classes allow

rapper classes rapper classes allow primitive values you know such as as

primitive values you know such as as integers characters doubles booleans

integers characters doubles booleans those sorts of things rapper classes

those sorts of things rapper classes allow these primitive values to be

allow these primitive values to be treated as objects or basically wrapping

treated as objects or basically wrapping primitive values within an object kind

primitive values within an object kind of like a Christmas present generally

of like a Christmas present generally you don't need to wrap Primitives unless

you don't need to wrap Primitives unless you need an object for some reason like

you need an object for some reason like if you're using a collections framework

if you're using a collections framework in Java and rapper classes also give you

in Java and rapper classes also give you access to a lot of useful static utility

access to a lot of useful static utility methods so let me give you a

methods so let me give you a demonstration of rapper

demonstration of rapper classes the method of creating rapper

classes the method of creating rapper classes I'm about about to show you is

classes I'm about about to show you is actually depreciated but it's going to

actually depreciated but it's going to help you visualize how this works

help you visualize how this works wrapping A Primitive within an object

wrapping A Primitive within an object the modern approach is using a technique

the modern approach is using a technique called autoboxing but the method I'm

called autoboxing but the method I'm about to show you is a good way to

about to show you is a good way to visualize this whole thing so let's say

visualize this whole thing so let's say we have an INT of a variable a a equal

we have an INT of a variable a a equal 123 we can treat this primitive as an

123 we can treat this primitive as an object by using a wrapper class here's

object by using a wrapper class here's how rather than declaring this variable

how rather than declaring this variable as an INT

as an INT we will use the rapper class of integer

we will use the rapper class of integer integer variable a equals a new integer

integer variable a equals a new integer and then we're going to pass in that

and then we're going to pass in that number that integer as an argument a is

number that integer as an argument a is an object we're passing in that

an object we're passing in that primitive data type that int as an

primitive data type that int as an argument to the integer class so a is an

argument to the integer class so a is an object but it does contain A Primitive

object but it does contain A Primitive value again this is depreciated as a

value again this is depreciated as a version 9 so you shouldn't do it this

version 9 so you shouldn't do it this way but this is a good way to visualize

way but this is a good way to visualize it then if you need a double we'll use

it then if you need a double we'll use the wrapper class of double let's say

the wrapper class of double let's say variable b equals a new double then

variable b equals a new double then we'll pass in a double 3.14 is

we'll pass in a double 3.14 is good then we have char which is

good then we have char which is character that's the rapper class

character that's the rapper class character C equals a new character then

character C equals a new character then pass in a character I'll pass in a

pass in a character I'll pass in a dollar

dollar sign We'll add one more let's say a

sign We'll add one more let's say a Boolean we will use the wrapper class of

Boolean we will use the wrapper class of Boolean Boolean D equals a new boan then

Boolean Boolean D equals a new boan then pass in a Boolean

pass in a Boolean value here's just a few examples these

value here's just a few examples these are all objects a b c and d by wrapping

are all objects a b c and d by wrapping these Primitives within an object that

these Primitives within an object that allows us to use these primitive values

allows us to use these primitive values within collections Frameworks such as

within collections Frameworks such as array lists which we'll talk about in

array lists which we'll talk about in the next topic the modern way to use

the next topic the modern way to use rapper classes is actually just to

rapper classes is actually just to assign them directly to their primitive

assign them directly to their primitive values the class of integer a equals

values the class of integer a equals 123 doubleb equal

123 doubleb equal 3.14 character C equals a dollar sign

3.14 character C equals a dollar sign character and then D equals

character and then D equals true this technique is called

true this technique is called autoboxing We're directly assigning

autoboxing We're directly assigning these Primitives into an object using a

these Primitives into an object using a rapper class now this is very similar to

rapper class now this is very similar to how we declare and assign strings to

how we declare and assign strings to create a string you would say string

create a string you would say string let's say E equals a string of

let's say E equals a string of characters such as the word Pizza you

characters such as the word Pizza you can see that there's a similar pattern

can see that there's a similar pattern we have always created strings this way

we have always created strings this way but with autoboxing it's a similar

but with autoboxing it's a similar process these are all reference data

process these are all reference data types they're a type of

types they're a type of object there's also a technique called

object there's also a technique called unboxing to convert a rapper class back

unboxing to convert a rapper class back to its primitive this is

to its primitive this is unboxing so let's say we would like to

unboxing so let's say we would like to convert our object of a it's an integer

convert our object of a it's an integer object back to its primitive let's say

object back to its primitive let's say int x equals all you got to do is set it

int x equals all you got to do is set it equal to your object in this case our

equal to your object in this case our integer object of a this is unboxing

integer object of a this is unboxing we're taking a primitive that's wrapped

we're taking a primitive that's wrapped in an object and unboxing it we

in an object and unboxing it we unwrapping it and setting it back to its

unwrapping it and setting it back to its primitive if we were unboxing a double

primitive if we were unboxing a double we would say double some variable equals

we would say double some variable equals b or chars Char x

b or chars Char x equals our character object of c and

equals our character object of c and then Boolean Boolean x equals D again

then Boolean Boolean x equals D again this is autoboxing we're wrapping up a

this is autoboxing we're wrapping up a Christmas present we're wrapping up a

Christmas present we're wrapping up a primitive within an object and then

primitive within an object and then unboxing is removing it we're opening

unboxing is removing it we're opening the Christmas present now these rapper

the Christmas present now these rapper classes themselves do have some pretty

classes themselves do have some pretty useful utility methods that are static

useful utility methods that are static let me demonstrate a few you might be

let me demonstrate a few you might be interested in but there would be too

interested in but there would be too many to cover in just this one video if

many to cover in just this one video if you ever need to convert a primitive

you ever need to convert a primitive data type into a string there's a two-

data type into a string there's a two- string method of these utility classes

string method of these utility classes so let's say we have string

so let's say we have string a string

a string B string

B string C and string

D I can convert an integer into a string using the integer wrapper class it's ACC

using the integer wrapper class it's ACC statically so we type the name of the

statically so we type the name of the class integer called the two string

class integer called the two string method which is static and then pass it

method which is static and then pass it an integer like

an integer like 123 so let's do this with the

123 so let's do this with the double we will access the double wrapper

double we will access the double wrapper class called the two string method and

class called the two string method and then pass in a double

then pass in a double 3.14 then to convert a character to a

3.14 then to convert a character to a string we would use the character

string we would use the character wrapper class character to string and

wrapper class character to string and then pass in a character

then pass in a character and then

and then Boolean we will access the Boolean

Boolean we will access the Boolean wrapper class called the two string

wrapper class called the two string method and then pass in a

method and then pass in a Boolean so strings can be concatenated

Boolean so strings can be concatenated together we should be able to do the

together we should be able to do the following let's say string X = A + B + C

following let's say string X = A + B + C +

+ D and then we'll output whatever our

D and then we'll output whatever our variable X is

we get 1 123 3.14 at false it's all one long string it's because we use these

long string it's because we use these rapper classes to convert these

rapper classes to convert these primitive data types into Strings if you

primitive data types into Strings if you ever need to convert a primitive to a

ever need to convert a primitive to a string then use that primitive data

string then use that primitive data types rapper class and call the two

types rapper class and call the two string method then you just need to pass

string method then you just need to pass that value in as an argument then it's

that value in as an argument then it's going to spit out a string for you now

going to spit out a string for you now on the other hand to convert a string to

on the other hand to convert a string to a primitive data type there's another

a primitive data type there's another useful utility method of wrapper classes

useful utility method of wrapper classes so what we'll do is

so what we'll do is parsing we will have an INT of

parsing we will have an INT of a a double of

a a double of B A Char of

B A Char of c and a Boolean of

D int a will equal we're going to call the integer wrapper class call a static

the integer wrapper class call a static method of parse int we can convert a

method of parse int we can convert a string to an integer I will convert a

string to an integer I will convert a string of 123 to an

string of 123 to an integer now with doubles you will call

integer now with doubles you will call the double wrapper class and we will

the double wrapper class and we will parse a

parse a double we'll pass in a string of

double we'll pass in a string of 3.14 now characters don't have a parse

3.14 now characters don't have a parse method what you could do instead is with

method what you could do instead is with any string let's say we have a string of

any string let's say we have a string of pizza strings do have built-in methods

pizza strings do have built-in methods one of which is the Char at

one of which is the Char at method return the character the first

method return the character the first position where index is zero again

position where index is zero again character doesn't have a parse character

character doesn't have a parse character method so you would have to use charart

method so you would have to use charart at which is unrelated to wrapper

at which is unrelated to wrapper classes so then with the

classes so then with the Boolean we would access the Boolean

Boolean we would access the Boolean wrapper class called the parse Boolean

wrapper class called the parse Boolean method and we can convert a string

method and we can convert a string representation of a Boolean such as true

representation of a Boolean such as true into an actual Boolean and then let's

into an actual Boolean and then let's output them now we shouldn't be able to

output them now we shouldn't be able to add these together much like what we did

add these together much like what we did when we used the two string method for

when we used the two string method for example string X = A + B + C + D this

example string X = A + B + C + D this isn't going to work because we're mixing

isn't going to work because we're mixing and matching different data types and

and matching different data types and then if I was to Output

X that would give us a compilation error to convert a string to its primitive

to convert a string to its primitive data type there is various parse methods

data type there is various parse methods to handle that within our rapper classes

to handle that within our rapper classes it depends on the data type you're

it depends on the data type you're working with

working with there's a couple other miscellaneous

there's a couple other miscellaneous utility methods within rapper classes

utility methods within rapper classes I'll just cover two more so let's say we

I'll just cover two more so let's say we have a Char of letter pick a

have a Char of letter pick a letter I will pick the letter lowercase

letter I will pick the letter lowercase B I'm going to use a print line

B I'm going to use a print line statement we can check to see if our

statement we can check to see if our letter actually is a letter we can

letter actually is a letter we can access the character wrapper class call

access the character wrapper class call the is letter method and then pass in

the is letter method and then pass in our letter

our letter this returns a Boolean true or false is

this returns a Boolean true or false is this character a

this character a letter that is

letter that is true this would be useful for verifying

true this would be useful for verifying user input what if this was a dollar

user input what if this was a dollar sign is this a letter well this returns

sign is this a letter well this returns false that is not a

false that is not a letter I'll switch this back to

letter I'll switch this back to lowercase b there's also a built-in

lowercase b there's also a built-in method to check to see if this letter is

method to check to see if this letter is uppercase or not there's a built-in

uppercase or not there's a built-in utility method of the character rapper

utility method of the character rapper class class to check to see if this is

class class to check to see if this is uppercase or

uppercase or not

not character is uppercase and then pass in

character is uppercase and then pass in our letter is it uppercase currently it

our letter is it uppercase currently it isn't that is

isn't that is false but if it were

false but if it were uppercase that returns

uppercase that returns true some of these utility methods of

true some of these utility methods of the character rapper class would be

the character rapper class would be great for verifying user input like a

great for verifying user input like a username or a password all right

username or a password all right everybody so those are wrapper classes

everybody so those are wrapper classes we're basically taking a primitive and

we're basically taking a primitive and wrapping it in an object kind of like a

wrapping it in an object kind of like a Christmas present in the next topic

Christmas present in the next topic we're going to be working with array

we're going to be working with array lists and array lists only work with

lists and array lists only work with objects so we need to utilize these

objects so we need to utilize these rapper classes in order to work with

rapper classes in order to work with array lists and wrapper classes do

array lists and wrapper classes do provide some useful static utility

provide some useful static utility methods that you can always access all

methods that you can always access all right everybody and those are wrapper

right everybody and those are wrapper classes and in the next video we're

classes and in the next video we're going to cover array lists all right

going to cover array lists all right people it's about time we get to array

people it's about time we get to array lists and Java an array list is a

lists and Java an array list is a resizable array that stores objects you

resizable array that stores objects you can store Primitives if so you'll be

can store Primitives if so you'll be using autoboxing which we learned about

using autoboxing which we learned about in the last topic on rapper classes

in the last topic on rapper classes arrays are fixed in size but array lists

arrays are fixed in size but array lists can change they're Dynamic here's how to

can change they're Dynamic here's how to create an array list first we'll follow

create an array list first we'll follow our similar pattern with creating many

our similar pattern with creating many objects in Java array list let's say

objects in Java array list let's say list equals new array list we will need

list equals new array list we will need to make One Import import java. u.

to make One Import import java. u. arraylist following the type of array

arraylist following the type of array list we're going to use the diamond

list we're going to use the diamond operator this has to deal with generics

operator this has to deal with generics which is a future topic but for now

which is a future topic but for now we're going to specify what type of

we're going to specify what type of object we're going to be storing within

object we're going to be storing within our array list and you can always use

our array list and you can always use the appropriate wrapper class to store

the appropriate wrapper class to store Primitives for example if you need to

Primitives for example if you need to store integers you can say integer and

store integers you can say integer and then we do need that diamond operator

then we do need that diamond operator after the second array list

after the second array list you don't also need to specify the data

you don't also need to specify the data type within the second Diamond operator

type within the second Diamond operator Java can infer that you're going to

Java can infer that you're going to follow this pattern to create an array

follow this pattern to create an array list this array list can store integers

list this array list can store integers you just have to specify that type so

you just have to specify that type so for example let's take our list and add

for example let's take our list and add a few

a few numbers

two and then we can print our list our list I will print our

list I will print our list and we have three numbers

list and we have three numbers 312 now if you were storing doubles you

312 now if you were storing doubles you would set the type to be double and use

would set the type to be double and use the double wrapper class 3.14 1.99

the double wrapper class 3.14 1.99 2.01 I'm just making up numbers

2.01 I'm just making up numbers here there we go so let's store

here there we go so let's store strings let's create an array list named

strings let's create an array list named fruits we will store the names of some

fruits we will store the names of some fruit so the array name is going to be

fruit so the array name is going to be fruits and then we will print our array

fruits and then we will print our array list of fruits think of some fruit I

list of fruits think of some fruit I will add an

apple an orange a

orange a banana and a coconut that should be good

banana and a coconut that should be good enough for this

example and now we have an array list of strings named fruits Apple Orange banana

strings named fruits Apple Orange banana coconut to add an element to an array

coconut to add an element to an array list you can use the add method add is a

list you can use the add method add is a built-in method of array lists to remove

built-in method of array lists to remove an element you can use the remove method

an element you can use the remove method then specify an index so let's take

then specify an index so let's take fruits and remove the element at index

fruits and remove the element at index zero that should get rid of our

Apple then we have orange banana coconut if we were to remove the element

coconut if we were to remove the element at index one that should get rid of our

at index one that should get rid of our orange apple banana Coco

orange apple banana Coco nut there's also the set method take our

nut there's also the set method take our Ray list of fruits called the set method

Ray list of fruits called the set method add a certain index let's say zero we

add a certain index let's say zero we can set that element to be something

can set that element to be something else let's replace apple with

else let's replace apple with pineapple replace the element at index

pineapple replace the element at index zero with

zero with pineapple then we have pineapple orange

pineapple then we have pineapple orange banana coconut or index

banana coconut or index one would be apple pineapple banana

one would be apple pineapple banana coconut

coconut that's the set

that's the set method with an array list to get an

method with an array list to get an element at a certain index you can use

element at a certain index you can use the get method then specify the element

the get method then specify the element number get the element at index zero

number get the element at index zero that's going to return

that's going to return Apple get the element at index one would

Apple get the element at index one would be

be orange

orange two

two banana

banana 3

3 coconut you can also get the size of an

coconut you can also get the size of an array list take your array list call the

array list take your array list call the size method that will return the total

size method that will return the total amount of elements within your array

amount of elements within your array list so my array list has four

list so my array list has four elements to sort your array list you

elements to sort your array list you will use the collections framework call

will use the collections framework call the sort method and then pass in your

the sort method and then pass in your array list our array list is named

array list our array list is named fruits and then you do need to import

fruits and then you do need to import this

this class java.util doc collections

class java.util doc collections after sorting our array list let's print

after sorting our array list let's print it print my array list of

it print my array list of fruits so these all should be in

fruits so these all should be in alphabetical order starting with a for

alphabetical order starting with a for apple b for banana C for coconut o for

apple b for banana C for coconut o for orange so that's how to sort an array

orange so that's how to sort an array list you can use the collections

list you can use the collections framework you could use an enhanced for

framework you could use an enhanced for Loop to iterate through all the elements

Loop to iterate through all the elements of an array list so the data type of my

of an array list so the data type of my aray list is strings we specified that

aray list is strings we specified that type for every fruit in my array list of

type for every fruit in my array list of fruits let's print each

fruit and here they are apple banana coconut

coconut orange all right so now we're going to

orange all right so now we're going to cover an

exercise we'll create an array and accept user input a user will enter in

accept user input a user will enter in all the food that they want within this

all the food that they want within this array list so to help us with this

array list so to help us with this exercise we will need a scanner scanner

exercise we will need a scanner scanner scanner equals new scanner

scanner equals new scanner pass in

pass in system.in import this class and then be

system.in import this class and then be sure to close your scanner at the end

sure to close your scanner at the end because I tend to forget scanner.

because I tend to forget scanner. close we'll need an array

close we'll need an array list again we'll follow a similar

list again we'll follow a similar pattern with creating objects array list

pattern with creating objects array list let's say list equals new array

let's say list equals new array list using the diamond operator we're

list using the diamond operator we're going to specify the type of what we're

going to specify the type of what we're storing within this array list we'll

storing within this array list we'll stick with

strings let's rename our list as Foods we'll be storing some food well at least

we'll be storing some food well at least the name of

the name of food we'll create a prompt we'll ask a

food we'll create a prompt we'll ask a user enter the number of food they would

user enter the number of food they would like to

like to store enter the number of food you would

store enter the number of food you would like and I'll use print rather than

like and I'll use print rather than print line for the user input

print line for the user input we'll create a variable of num of food

we'll create a variable of num of food to store the number of food that we're

to store the number of food that we're going to store equals take our scanner

going to store equals take our scanner call the next int method to get the next

call the next int method to get the next integer from the

integer from the user once we accept an integer we should

user once we accept an integer we should clear the input buffer because there's

clear the input buffer because there's going to be a new line character within

going to be a new line character within there take our scanner call the next

there take our scanner call the next line method to clear it let's do a test

line method to clear it let's do a test run and enter the number of food you

run and enter the number of food you would like I'll just say three and that

would like I'll just say three and that seems to work for now we have the number

seems to work for now we have the number of food we're going to store within this

of food we're going to store within this array list in my example let's say I

array list in my example let's say I would like to enter three food items

would like to enter three food items well we could use a for Loop to iterate

well we could use a for Loop to iterate three times we will ask your user to

three times we will ask your user to enter in a food three times then so we

enter in a food three times then so we can use a for Loop for that within our

can use a for Loop for that within our for loop we're going to create a counter

for loop we're going to create a counter of I meaning index we can set that to be

of I meaning index we can set that to be zero or one let's stick with one we'll

zero or one let's stick with one we'll continue this for loop as long as I is

continue this for loop as long as I is less than or equal to our number of food

less than or equal to our number of food variable if I would like to enter in

variable if I would like to enter in four food items this would be four so we

four food items this would be four so we should iterate this Loop four times we

should iterate this Loop four times we will increment I by One during each

will increment I by One during each cycle of this

cycle of this Loop during each iteration of this Loop

Loop during each iteration of this Loop we will ask for a food item I'll use

we will ask for a food item I'll use print rather than print line we will ask

print rather than print line we will ask a user to enter food number

a user to enter food number then I'll add plus our index of I so

then I'll add plus our index of I so during the first cycle I is going to be

during the first cycle I is going to be one then 2 3 four so on and so

one then 2 3 four so on and so forth then I'll add a colon then a

forth then I'll add a colon then a space we'll create a local variable of

space we'll create a local variable of food this will be of the string data

food this will be of the string data type we will set this equal to use our

type we will set this equal to use our scanner called the next line method to

scanner called the next line method to get a line of text from the

get a line of text from the user once we have our string of food

user once we have our string of food we're going to add it to our array list

we're going to add it to our array list of Foods so take your array list of

of Foods so take your array list of foods call the ad method to add an

foods call the ad method to add an element we will add our string of food

element we will add our string of food to our array list of

to our array list of foods and then once we're done let's

foods and then once we're done let's print our array list using a print line

print our array list using a print line statement we will print our Ray list of

statement we will print our Ray list of foods all right let's test

foods all right let's test it enter the number of food you would

it enter the number of food you would like I'll say four so we should ask for

like I'll say four so we should ask for four food items enter food number one

four food items enter food number one I'll say

I'll say pizza hot

pizza hot dog hamburger and then

dog hamburger and then Taco and here's my array list of food

Taco and here's my array list of food pizza hot dog hamburger

pizza hot dog hamburger taco all right everybody those are array

taco all right everybody those are array lists an array list is a resizable array

lists an array list is a resizable array that stores objects you can store

that stores objects you can store Primitives you're just going to use

Primitives you're just going to use Java's autoboxing feature if that's the

Java's autoboxing feature if that's the case once you have your array list

case once you have your array list there's various methods to add remove

there's various methods to add remove move or set elements and well everybody

move or set elements and well everybody those are array lists in Java today I'm

those are array lists in Java today I'm going to talk about exceptions using

going to talk about exceptions using Java an exception is an event that

Java an exception is an event that interrupts the normal flow of a program

interrupts the normal flow of a program these exceptions pop up if you do things

these exceptions pop up if you do things like divide by zero you can't find a

like divide by zero you can't find a resource for some reason or if there's a

resource for some reason or if there's a mismatch with the input type let's say

mismatch with the input type let's say the program asks for a number and you

the program asks for a number and you type in a string of characters these

type in a string of characters these sorts of events interrupt your program

sorts of events interrupt your program they're called exceptions there's a way

they're called exceptions there's a way that we can handle them and that is by

that we can handle them and that is by using a few blocks of code try catch and

using a few blocks of code try catch and optionally finally so any code that's

optionally finally so any code that's considered dangerous where it might

considered dangerous where it might interrupt your program you can surround

interrupt your program you can surround with a tri block here's an example so

with a tri block here's an example so let's say I'm going to take the number

let's say I'm going to take the number one and divide it by zero mathematically

one and divide it by zero mathematically speaking you can't divide by

zero that causes an exception more specifically and arithmetic exception

specifically and arithmetic exception I'm actually just going to copy this and

I'm actually just going to copy this and save

save it this code is dangerous it's

it this code is dangerous it's interrupting our program by causing an

interrupting our program by causing an exception we can gracefully handle this

exception we can gracefully handle this exception so that it doesn't interrupt

exception so that it doesn't interrupt the normal flow of our program any

the normal flow of our program any dangerous code we're going to surround

dangerous code we're going to surround with a tri block try and a set of curly

braces there we go however if we have a Tri block we also need a catch

Tri block we also need a catch block we will catch any

block we will catch any exceptions but we're going to list the

exceptions but we're going to list the specific kind of exception we're going

specific kind of exception we're going to catch well let's catch that one

to catch well let's catch that one exception that arithmetic

exception that arithmetic exception this is the type we're setting

exception this is the type we're setting up a parameter here arithmetic exception

up a parameter here arithmetic exception is the type we will give this exception

is the type we will give this exception a name of e for a

a name of e for a nickname if we encounter this exception

nickname if we encounter this exception we can take a different course of action

we can take a different course of action instead of interrup the program so let's

instead of interrup the program so let's do the

do the following let's

following let's output you can't divide by zero idiot so

output you can't divide by zero idiot so if we run this again it shouldn't

if we run this again it shouldn't interrupt our

interrupt our program we catch this exception and

program we catch this exception and output this text

output this text instead so any code that's dangerous

instead so any code that's dangerous where it might cause an exception you

where it might cause an exception you can surround with the tri block you can

can surround with the tri block you can add more than one catch block to catch

add more than one catch block to catch and handle spefic specific exceptions so

and handle spefic specific exceptions so this time we're going to accept some

this time we're going to accept some user input we'll need a scanner for now

user input we'll need a scanner for now I'm going to write the scanner outside

I'm going to write the scanner outside of the tri Block near the end of this

of the tri Block near the end of this video there's a feature called used with

video there's a feature called used with resources I'll show you how to do that

resources I'll show you how to do that later scanner scanner equals new scanner

later scanner scanner equals new scanner type

type system.in and then import this

system.in and then import this class import java.util.scanner

class import java.util.scanner anytime you accept user input it's

anytime you accept user input it's almost always d dangerous code because a

almost always d dangerous code because a user can type in

user can type in anything this time let's prompt a user

anything this time let's prompt a user to enter a

to enter a number and I will use

number and I will use print let's create a local variable of

print let's create a local variable of int number equals use our scanner called

int number equals use our scanner called the next int method to accept an integer

the next int method to accept an integer and then we'll just output our

number and enter a number uh how about no I'm going to type in the word Pizza

no I'm going to type in the word Pizza instead well we get an exception an

instead well we get an exception an input mismatch exception Java was

input mismatch exception Java was expecting an integer but we typed in a

expecting an integer but we typed in a string instead we can handle these

string instead we can handle these exceptions too and I'm just going to

exceptions too and I'm just going to copy the name of this exception because

copy the name of this exception because we'll reuse it let's catch the following

we'll reuse it let's catch the following let's

let's catch any input mismatch

catch any input mismatch exceptions this is the type we will give

exceptions this is the type we will give this exception a nickname of e so this

this exception a nickname of e so this exception we actually do have to

exception we actually do have to import import java.util do input

import import java.util do input mismatch exception in case there's a

mismatch exception in case there's a mismatch with the data type we're asking

mismatch with the data type we're asking the user for a number but they type in a

the user for a number but they type in a string Let's help with the following

string Let's help with the following let's

let's say that wasn't a

say that wasn't a number let's try it

number let's try it again enter a number uh I'll type in the

again enter a number uh I'll type in the word I already did pizza let's do Taco

word I already did pizza let's do Taco that wasn't a

that wasn't a number and our program finished with no

number and our program finished with no problems you can catch and handle more

problems you can catch and handle more than one exception there is a catch all

than one exception there is a catch all statement that you could

add you could catch all exceptions exception e using this by itself isn't

exception e using this by itself isn't good

good practice you want to let a user know

practice you want to let a user know exactly what went wrong if all else

exactly what went wrong if all else fails and there's an exception that you

fails and there's an exception that you don't anticipate you could just say okay

don't anticipate you could just say okay something went

something went wrong you could technically use this by

itself enter a number for example I'll type in hot dog something went wrong

type in hot dog something went wrong this does prevent our program from being

this does prevent our program from being interrupted it is good practice to let

interrupted it is good practice to let the user know what went wrong exactly

the user know what went wrong exactly I'm looking at you Microsoft catching

I'm looking at you Microsoft catching all exceptions acts as some sort of

all exceptions acts as some sort of safety net you should only do it at the

safety net you should only do it at the end in case there's something you don't

end in case there's something you don't anticipate it is better to catch and

anticipate it is better to catch and handle specific types of exceptions

handle specific types of exceptions because you can let the user know what

because you can let the user know what went wrong

went wrong exactly now there's also the finally

exactly now there's also the finally block this is

block this is optional finally will always execute

optional finally will always execute whether there's an exception or not this

whether there's an exception or not this is where you might clean up any

is where you might clean up any resources for example with my scanner I

resources for example with my scanner I forgot to close it we can actually close

forgot to close it we can actually close it within the final

it within the final block when we're done with our scanner

block when we're done with our scanner let's close it

let's close it because if we encounter an exception we

because if we encounter an exception we might not close the scanner other times

might not close the scanner other times finally might be useful is if you open a

finally might be useful is if you open a file within a tri

file within a tri block then you'll want to close the file

block then you'll want to close the file when you're done with it you can do that

when you're done with it you can do that within the finally block for testing

within the finally block for testing purposes I'm just going to add this

purposes I'm just going to add this always

always executes all right let's do a test

executes all right let's do a test run enter a number I'll type in 12 three

run enter a number I'll type in 12 three and then we output 123 see that finally

and then we output 123 see that finally block does execute this always

block does execute this always executes if we encounter an exception

executes if we encounter an exception enter a number I will type in

enter a number I will type in Taco we get our exception message for

Taco we get our exception message for input mismatch and then that finally

input mismatch and then that finally block does

block does execute finally is quite often used for

execute finally is quite often used for cleanup cleaning up your program when

cleanup cleaning up your program when you're done with it when you open a file

you're done with it when you open a file or resource you want to close it we'll

or resource you want to close it we'll have more practice with this on the next

have more practice with this on the next topic of file handling now there's also

topic of file handling now there's also try with

try with resources and actually Java is

resources and actually Java is recommending this rather than declaring

recommending this rather than declaring our scanner outside of the tri block we

our scanner outside of the tri block we can place within a set of parentheses

can place within a set of parentheses and then Java is automatically going to

and then Java is automatically going to close those resources when it's done

close those resources when it's done opening them so this works

opening them so this works too so enter a number

123 enter a number Pizza that wasn't a number

Pizza that wasn't a number all right everybody so those are

all right everybody so those are exceptions they're events that interrupt

exceptions they're events that interrupt the normal flow of a program exceptions

the normal flow of a program exceptions occur when you divide by zero you can't

occur when you divide by zero you can't locate a resource or there's a mismatch

locate a resource or there's a mismatch of the input type that a user types in

of the input type that a user types in you'll want to surround any dangerous

you'll want to surround any dangerous code with a tri block anytime you accept

code with a tri block anytime you accept user input or try and locate an external

user input or try and locate an external resource that's almost always dangerous

resource that's almost always dangerous code try any dangerous code catch any

code try any dangerous code catch any exceptions and optionally you can add

exceptions and optionally you can add finally to do any resource cleanup and

finally to do any resource cleanup and well everybody those are exceptions in

well everybody those are exceptions in Java all right everybody in this video

Java all right everybody in this video I'm going to show you how you can write

I'm going to show you how you can write a file using Java after doing some

a file using Java after doing some research I've encountered four popular

research I've encountered four popular options the first way I'm about to show

options the first way I'm about to show you is the most simple and is what I'll

you is the most simple and is what I'll be demonstrating in this topic we'll be

be demonstrating in this topic we'll be using a file writer object it's good for

using a file writer object it's good for writing small or medium-sized text files

writing small or medium-sized text files there's also buffered writer this has

there's also buffered writer this has better performance for large amounts of

better performance for large amounts of text print writer is best for structure

text print writer is best for structure data like reports or logs then there's

data like reports or logs then there's file output stream which is best for

file output stream which is best for binary files such as images or audio

binary files such as images or audio files files of that nature in this topic

files files of that nature in this topic I'm going to cover file writer just so

I'm going to cover file writer just so we get the hang of the basics I might

we get the hang of the basics I might make videos on the other writers but I

make videos on the other writers but I haven't decided yet here's how we can

haven't decided yet here's how we can write a basic file using Java we'll need

write a basic file using Java we'll need a file writer object file writer I'll

a file writer object file writer I'll name this file writer just writer for

name this file writer just writer for short equals new file

short equals new file writer then we need to pass in a file

writer then we need to pass in a file path or a file name let's create a file

path or a file name let's create a file named test and include a file extension

named test and include a file extension let's say it's a txt file a plain text

let's say it's a txt file a plain text file now you could include an absolute

file now you could include an absolute file path I'll show you how to do that

file path I'll show you how to do that later our plain text file a test is

later our plain text file a test is going to appear in our source folder

going to appear in our source folder reading or writing files is kind of

reading or writing files is kind of unpredictable you could consider that

unpredictable you could consider that dangerous code any dangerous code we

dangerous code any dangerous code we want to enclose within a tri block try

want to enclose within a tri block try this dangerous code catch any exceptions

this dangerous code catch any exceptions that might interrupt our

that might interrupt our program with modern Java you can try and

program with modern Java you can try and open up some resource add a set of

open up some resource add a set of parentheses after try we will try to

parentheses after try we will try to open up a file writer

object so file writer writer equals new file writer then we have our file name

file writer then we have our file name including the

including the extension now we do have to import this

extension now we do have to import this class import

class import java. file writer

java. file writer if for some reason we can't write this

if for some reason we can't write this file we might encounter an exception we

file we might encounter an exception we will catch any IO exceptions IO meaning

will catch any IO exceptions IO meaning input output catch any input output

input output catch any input output exceptions that's the type we will give

exceptions that's the type we will give this exception a nickname of

this exception a nickname of e then we do have to import this class

e then we do have to import this class too in order to work with IO exceptions

too in order to work with IO exceptions java.io doio

java.io doio exception in case there's a problem

exception in case there's a problem writing this file we'll catch this

writing this file we'll catch this exception if it comes up this acts as

exception if it comes up this acts as more of a safety net if we encounter

more of a safety net if we encounter this exception we can say something

this exception we can say something generic such as could not write file but

generic such as could not write file but it is best practice to handle specific

it is best practice to handle specific kind of exceptions first momentarily

kind of exceptions first momentarily we're going to add a catch clause for a

we're going to add a catch clause for a file not found exception in case we

file not found exception in case we can't locate a file path but we'll take

can't locate a file path but we'll take care of that in a moment within the tri

care of that in a moment within the tri Block in order to write a file using

Block in order to write a file using Java using file writer we will take our

Java using file writer we will take our file writer which we named

file writer which we named writer called the write method and then

writer called the write method and then pass in a

pass in a string let's say I like then pick your

string let's say I like then pick your favorite food as you know my favorite

favorite food as you know my favorite food is

food is pizza then after writing this file if we

pizza then after writing this file if we don't encounter any exceptions we'll

don't encounter any exceptions we'll print a confirmation

print a confirmation message let's say the

message let's say the following file has been

following file has been written all right let's test this

written since we didn't specify a file path your file is likely going to be

path your file is likely going to be within your Source folder and here's

within your Source folder and here's mine test.txt and it says the following

mine test.txt and it says the following I like

I like pizza now you could pick a different

pizza now you could pick a different location for example you could use an

location for example you could use an absolute file path so let's say I would

absolute file path so let's say I would like to write this file to my desktop so

like to write this file to my desktop so what I could do I'm going to go to my

what I could do I'm going to go to my desktop I'm going to get the file

desktop I'm going to get the file location my desktop I'll just right

location my desktop I'll just right click on one of these

click on one of these folders go to properties copy this

folders go to properties copy this location then I'm going to paste that

location then I'm going to paste that file

path you'll likely need to use double forward slashes Java interprets a single

forward slashes Java interprets a single forward slash as an escape sequence so

forward slash as an escape sequence so you may need to use double slashes when

you may need to use double slashes when I write this file it should be at this

I write this file it should be at this location this absolute file path Let's

location this absolute file path Let's test it

test it file has been written let's go to my

file has been written let's go to my desktop and here's that

desktop and here's that file

file test it says I like

pizza let's say that we get the file path wrong instead of desktop I'll

path wrong instead of desktop I'll misspell this as

misspell this as deskto run this again we counter that

deskto run this again we counter that exception could not write file that's

exception could not write file that's because Java couldn't locate this file

because Java couldn't locate this file path I misspelled it now when handling

path I misspelled it now when handling exceptions it is best practice to catch

exceptions it is best practice to catch specific types of exceptions first here

specific types of exceptions first here we're relying solely on our safety net

we're relying solely on our safety net that catches all input output exceptions

that catches all input output exceptions another kind of exception that we can

another kind of exception that we can catch is the

catch is the following file not

following file not found exception we will give this a

found exception we will give this a nickname of e then we do need to import

nickname of e then we do need to import this class

this class java.io file not found

java.io file not found exception this this is if we can't

exception this this is if we can't locate a file or a file path is

locate a file or a file path is invalid so let's output the

invalid so let's output the following could not locate file location

following could not locate file location let's try that again remember that my

let's try that again remember that my file path is

file path is misspelled could not locate file

misspelled could not locate file location let's spell this correctly this

location let's spell this correctly this time I'm going to delete this

time I'm going to delete this file maybe I'll add another line of text

file maybe I'll add another line of text I like

I like pizza it's really good okay let's try

pizza it's really good okay let's try that

that again file has been written going to my

again file has been written going to my desktop here's that file and it says I

desktop here's that file and it says I like pizza it's really

like pizza it's really good for better organization what you

good for better organization what you could do is create a string a file path

could do is create a string a file path and set that equal to a

and set that equal to a string we're going to cut everything

string we're going to cut everything within our file

within our file writer and paste it within the string

writer and paste it within the string we're going to assign the string of text

we're going to assign the string of text equal to a string variable a file path

equal to a string variable a file path then we'll pass in the string variable

then we'll pass in the string variable to the file

to the file writer and instead of passing in a

writer and instead of passing in a string literal to the right method of a

string literal to the right method of a file writer for better organization

file writer for better organization let's create a string of let's say text

let's create a string of let's say text content equals and then we'll cut our

text and then pass in the text content let's see I'll add another line

content let's see I'll add another line I like pizza it's really

I like pizza it's really good buy me

good buy me pizza okay let's run this

pizza okay let's run this again file has been written go to our

again file has been written go to our test file and here's our test file I

test file and here's our test file I like pizza it's really good buy me pizza

like pizza it's really good buy me pizza if you have a string that takes up

if you have a string that takes up multiple lines another option is to

multiple lines another option is to write a multi-line string by using a

write a multi-line string by using a triple set of double quotes So This is

triple set of double quotes So This is if you have a lot of

if you have a lot of text this time I'm going to write a

text this time I'm going to write a poem roses are

poem roses are red violets are

red violets are blue booty booty

blue booty booty booty rocking everywhere

booty rocking everywhere all right so this is a multi-line string

all right so this is a multi-line string you use a triple set of double

you use a triple set of double quotes that's if you have a lot of text

quotes that's if you have a lot of text to write okay let's test it

to write okay let's test it again file has been written let's go to

again file has been written let's go to our desktop open this file and here's

our desktop open this file and here's our poem roses are red violets are blue

our poem roses are red violets are blue booty booty booty rocking

booty booty booty rocking everywhere all right everybody so that

everywhere all right everybody so that is how to write a file using Java to

is how to write a file using Java to write small or mediumsized textt files

write small or mediumsized textt files you can use a file right writer but you

you can use a file right writer but you will need a try and catch block and well

will need a try and catch block and well everybody that's how to write a file

everybody that's how to write a file using Java hey everybody in this video

using Java hey everybody in this video I'm going to show you how we can read a

I'm going to show you how we can read a file using Java after doing some

file using Java after doing some research there's three popular options

research there's three popular options the first and which I'll demonstrate in

the first and which I'll demonstrate in this video is to combine a buffered

this video is to combine a buffered reader and a file reader both together

reader and a file reader both together this technique is best for reading text

this technique is best for reading text files line by line buffered reader can't

files line by line buffered reader can't read a file by itself you can say that

read a file by itself you can say that it acts as a middleman between the

it acts as a middleman between the program and the file system it helps us

program and the file system it helps us read files more efficiently and a file

read files more efficiently and a file reader is what actually reads the file

reader is what actually reads the file so we'll be using these two together

so we'll be using these two together which I will demonstrate momentarily

which I will demonstrate momentarily another technique is to use a file input

another technique is to use a file input stream which is best for binary files

stream which is best for binary files such as images and audio files then

such as images and audio files then there's also Random Access file that's

there's also Random Access file that's best for reading or writing specific

best for reading or writing specific portions of a large file so use this if

portions of a large file so use this if you need to read something specific from

you need to read something specific from a big file in today's video we're going

a big file in today's video we're going to combine a buffered reader and a file

to combine a buffered reader and a file reader together but first we need a file

reader together but first we need a file to work with pick a location where you

to work with pick a location where you would like to read this file from for me

would like to read this file from for me I'm going to create a file on my desktop

I'm going to create a file on my desktop I will create a new text document I'll

I will create a new text document I'll name this

name this test and what should our file say think

test and what should our file say think of something to write so there's a poem

of something to write so there's a poem that I like to use roses are

that I like to use roses are red violets are

red violets are blue booty booty

blue booty booty booty rocking

everywhere we will need the name of this file including the file extension I'm

file including the file extension I'm going to right click go to

going to right click go to properties this file is a plain text

properties this file is a plain text file a txt file I'm going to copy this

location I will create a string variable named file path equals then within a set

named file path equals then within a set of quotes cuz we're working with strings

of quotes cuz we're working with strings I will paste that file path and include

I will paste that file path and include the file name including the extension

the file name including the extension test.txt

test.txt now we're going to be combining a

now we're going to be combining a buffered reader and a file reader

buffered reader and a file reader together first we will create a buffered

together first we will create a buffered reader

reader object

object buffered reader we'll name this reader

buffered reader we'll name this reader equals new buffer

reader we will need to import this class import

class import java.io buffered reader

java.io buffered reader we can't create a buffered reader object

we can't create a buffered reader object without first passing in a reader object

without first passing in a reader object which is why we'll be combining this

which is why we'll be combining this with a file reader object within the

with a file reader object within the Constructor we'll be passing in an

Constructor we'll be passing in an object a new file reader

object a new file reader object and then we do need to import

object and then we do need to import this class

this class too import java.io file reader within

too import java.io file reader within the Constructor of our file reader we're

the Constructor of our file reader we're going to pass in that file path that

going to pass in that file path that string

string when reading and writing files you'll

when reading and writing files you'll need try and catch blocks you can see

need try and catch blocks you can see that Java is already giving us a warning

that Java is already giving us a warning when working with files it's considered

when working with files it's considered dangerous code because you don't know if

dangerous code because you don't know if you'll actually locate that file or not

you'll actually locate that file or not or reading or writing that file might be

or reading or writing that file might be unsuccessful for some reason we will use

unsuccessful for some reason we will use a try and catch block try this dangerous

a try and catch block try this dangerous code catch any

code catch any exceptions with modern Java you can use

exceptions with modern Java you can use with

with resources we will add a set of

resources we will add a set of parentheses after

parentheses after try copy the snippet of code where we

try copy the snippet of code where we create a buffered reader

create a buffered reader object and then paste it within that set

object and then paste it within that set of parentheses remove the semicolon when

of parentheses remove the semicolon when using try with resources you'll

using try with resources you'll automatically close this reader when

automatically close this reader when you're done with it we're going to catch

you're done with it we're going to catch any file not found exceptions within the

any file not found exceptions within the catch

catch block so catch file not found exception

block so catch file not found exception that's the type we will give this

that's the type we will give this exception a nickname of e within the

exception a nickname of e within the parameter and we do need to import this

parameter and we do need to import this class as well import java.io file not

class as well import java.io file not found

found exception if for some reason we can't

exception if for some reason we can't locate this file at this file location

locate this file at this file location let's output the

let's output the following could not locate

following could not locate file to catch all other input output

file to catch all other input output exceptions We'll add another catch block

exceptions We'll add another catch block this will act as a safety

this will act as a safety net we will catch any

net we will catch any IO exceptions IO exception we will give

IO exceptions IO exception we will give it a nickname name of

it a nickname name of e this is where we'll say something went

e this is where we'll say something went wrong and import this class as

wrong and import this class as well just temporarily within our Tri

well just temporarily within our Tri block I'm going to Output that file

block I'm going to Output that file exists so let's test

exists so let's test it that file

it that file exists so that file is at this file

exists so that file is at this file location on my

location on my desktop for some reason if we can't

desktop for some reason if we can't locate that file let's say that I

locate that file let's say that I misspell desktop as deskto run this

misspell desktop as deskto run this again well we get that exception that

again well we get that exception that file not found exception could not

file not found exception could not locate

locate file let's make sure the file path is

file let's make sure the file path is correct now here's how to actually read

correct now here's how to actually read the file within our Tri block let's

the file within our Tri block let's create a local variable of line we'll be

create a local variable of line we'll be reading our file line by

line since we're reading the file line by line we'll be using a while

by line we'll be using a while loop during each cycle of the while loop

loop during each cycle of the while loop we're going to write the following

we're going to write the following within a set of parentheses we're going

within a set of parentheses we're going to set our string of line equal to use

to set our string of line equal to use our buffered reader object call the read

our buffered reader object call the read line method we're taking our reader

line method we're taking our reader reading the current line this will

reading the current line this will return a string which we're assigning to

return a string which we're assigning to the string variable of line after

the string variable of line after reading one line our reader is going to

reading one line our reader is going to point to the next line however if we run

point to the next line however if we run out of lines the readline method is

out of lines the readline method is going to return null so we're going to

going to return null so we're going to continue reading lines while line does

continue reading lines while line does not equal a value of null use the reader

not equal a value of null use the reader read each line assign it to this

read each line assign it to this variable of line if we run out of lines

variable of line if we run out of lines if this is null we'll escape the while

if this is null we'll escape the while loop during each cycle of the while loop

loop during each cycle of the while loop we'll output each line it's going to be

we'll output each line it's going to be a string and now this should work let's

a string and now this should work let's test it

and here's our poem roses are red violets are blue booty booty booty

violets are blue booty booty booty rocking everywhere so that's one way in

rocking everywhere so that's one way in which you can read a file using Java you

which you can read a file using Java you can combine a buffered reader and a file

can combine a buffered reader and a file reader it's best for reading text files

reader it's best for reading text files line by line but there's other methods

line by line but there's other methods you should be aware of too such as file

you should be aware of too such as file input stream and random access file I'm

input stream and random access file I'm not sure if I'll make videos on these

not sure if I'll make videos on these yet and well everybody that's how to

yet and well everybody that's how to read a file using Java hey everybody in

read a file using Java hey everybody in this video we're going to create an

this video we're going to create an audio player using

audio player using [Music]

[Music] Java let's get started all right let's

Java let's get started all right let's get started everybody now in this

get started everybody now in this following project what I'm about to show

following project what I'm about to show you isn't compatible with MP3 files but

you isn't compatible with MP3 files but you could easily convert an MP3 file to

you could easily convert an MP3 file to a wave file you can do that online

a wave file you can do that online otherwise to play an MP3 file you'll

otherwise to play an MP3 file you'll need an external library or framework

need an external library or framework such as Java FX and I do have another

such as Java FX and I do have another video on that if you need some sample of

video on that if you need some sample of music you can always use YouTube's audio

music you can always use YouTube's audio library these songs are free to use as

library these songs are free to use as long as they're within the context of

long as they're within the context of YouTube you could search for songs find

YouTube you could search for songs find one that you like and download

one that you like and download it this is the song I picked it's

it this is the song I picked it's currently an MP3 file I'll need to

currently an MP3 file I'll need to convert it to a wave file you can easily

convert it to a wave file you can easily look up an mp3 to wave

look up an mp3 to wave converter select a

file convert to wave convert

download for convenience I'm going to put this on my

put this on my desktop I'll delete the MP3

desktop I'll delete the MP3 file and we now have a wave file to make

file and we now have a wave file to make this even more convenient I'll place

this even more convenient I'll place this wave file within my source

folder so that I don't need to use an absolute file path so we're ready to

absolute file path so we're ready to begin once we have a wave file we're

begin once we have a wave file we're going to create a string for our file

going to create a string for our file path

path you can use an absolute file path or

you can use an absolute file path or relative file path since this wave file

relative file path since this wave file is right next to my main Java file I can

is right next to my main Java file I can use a relative file path easily we're

use a relative file path easily we're going to copy the name of this file

going to copy the name of this file we're going to copy path file name and

we're going to copy path file name and then paste it within the string the song

then paste it within the string the song that I picked is a caring friend and

that I picked is a caring friend and this is a wave file be sure to include

this is a wave file be sure to include the extension too once we have our file

the extension too once we have our file path we'll create a file object but we

path we'll create a file object but we have to pass in our file file path as an

have to pass in our file file path as an argument to create a file object file

argument to create a file object file file equals new

file equals new file then within the Constructor we will

file then within the Constructor we will pass in our file path to the file

pass in our file path to the file Constructor then be sure to import this

Constructor then be sure to import this class for

class for file when handling files it's considered

file when handling files it's considered dangerous code because accessing files

dangerous code because accessing files can be unpredictable we'll use a try and

can be unpredictable we'll use a try and catch

catch block try this dangerous code catch any

block try this dangerous code catch any exceptions one exception that we may run

exceptions one exception that we may run into

into is an IO exception we'll give it a

is an IO exception we'll give it a nickname of e then be sure to import

nickname of e then be sure to import this

this class this catch statement will act as a

class this catch statement will act as a safety net to catch any unexpected IO

safety net to catch any unexpected IO exceptions here we'll output something

exceptions here we'll output something went wrong it is better to handle

went wrong it is better to handle specific kinds of exceptions first we

specific kinds of exceptions first we will do that momentarily within the tri

will do that momentarily within the tri block we will create an audio input

block we will create an audio input stream object that's the first step to

stream object that's the first step to playing audio the type of object is

playing audio the type of object is audio input

audio input stream let's name this object just audio

stream let's name this object just audio stream

stream equals we will access the audio system

equals we will access the audio system class we're accessing it statically so

class we're accessing it statically so we type the name of the class call the

we type the name of the class call the get audio let me zoom out a little get

get audio let me zoom out a little get audio input stream

audio input stream method and then we will we'll pass in

method and then we will we'll pass in our file

our file object be sure to import this class too

object be sure to import this class too we'll be doing a lot of importing so get

we'll be doing a lot of importing so get used to it now with the get audio input

used to it now with the get audio input stream method we have to add a catch

stream method we have to add a catch clause for any unsupported audio file

clause for any unsupported audio file exceptions well we can write a catch

exceptions well we can write a catch block for

block for that catch the following exception type

that catch the following exception type where the type is unsupported audio file

where the type is unsupported audio file exception this is if somebody tries to

exception this is if somebody tries to use an audio file that's not imported

use an audio file that's not imported not one of the following we will give

not one of the following we will give this a nickname of e import this class

this a nickname of e import this class then we'll output the

then we'll output the following audio file is not

supported be sure to import the audio input stream class

too now when you open this audio stream you do want to close it so in modern

you do want to close it so in modern Java you can use try with resources add

Java you can use try with resources add a of parentheses after try we will cut

a of parentheses after try we will cut the snippet of

the snippet of code and paste it within the set of

code and paste it within the set of parentheses delete the

parentheses delete the semicolon if you use triy with resources

semicolon if you use triy with resources you'll automatically close this object

you'll automatically close this object when you're done with it you don't need

when you're done with it you don't need that finally Clause so now we're going

that finally Clause so now we're going to create a clip

to create a clip object clip clip equals access the audio

object clip clip equals access the audio system class we're doing it

system class we're doing it statically call the get clip method

statically call the get clip method import this class for clip in simple

import this class for clip in simple terms a clip is like a music or Sound

terms a clip is like a music or Sound Player it allows you to load an audio

Player it allows you to load an audio file and then play pause stop or reset

file and then play pause stop or reset the audio so it gives you some

the audio so it gives you some controls and we do need a catch clause

controls and we do need a catch clause for this too for any line unavailable

for this too for any line unavailable exceptions so let's add that catch

exceptions so let's add that catch clause in case we encounter a line

clause in case we encounter a line unavailable exception

unavailable exception which we will nickname e you might

which we will nickname e you might encounter this exception if another

encounter this exception if another resource is trying to access that audio

resource is trying to access that audio file or if it's unplayable for some

file or if it's unplayable for some reason it's

reason it's unavailable we could output something

unavailable we could output something such

such as unable to access audio

as unable to access audio resource then import this class as well

resource then import this class as well there we

there we go once we have our clip it gives us

go once we have our clip it gives us some controls but we do have to use it

some controls but we do have to use it to open the audio stream

to open the audio stream object we will take our clip object call

object we will take our clip object call the open method and then pass in our

the open method and then pass in our audio stream

audio stream object the clip object which is our

object the clip object which is our player is going to open our audio

player is going to open our audio stream now we're not going to play it

stream now we're not going to play it quite yet before we actually do play it

quite yet before we actually do play it I'm going to add another catch

I'm going to add another catch Clause we're going to catch any file not

Clause we're going to catch any file not found exceptions if we can't locate our

found exceptions if we can't locate our audio file file not

audio file file not found exception of

found exception of e will

e will output could not

output could not locate file import this class

locate file import this class two so we have four catch blocks the

two so we have four catch blocks the last one acts as a safety net now let's

last one acts as a safety net now let's be sure that we can locate this file

be sure that we can locate this file first so

first so temporarily let's output no problems

temporarily let's output no problems detected I'm going to run this

detected I'm going to run this program could not locate

program could not locate file if that's the case with our

file if that's the case with our relative file path we're going to access

relative file path we're going to access the source folder then access that audio

the source folder then access that audio file there it is no problems

file there it is no problems detected if this file is unsupported

detected if this file is unsupported let's say it's MP3 I'll bring back my

let's say it's MP3 I'll bring back my MP3 file move it to my source folder

then I'll switch this to MP3 then we should get an unsupported

MP3 then we should get an unsupported audio file exception if that's the

audio file exception if that's the case yes audio file is not supported

case yes audio file is not supported because we're trying to use an MP3 file

because we're trying to use an MP3 file so let's switch that back to wave or

so let's switch that back to wave or whatever yours was

whatever yours was originally and delete our MP3 file we

originally and delete our MP3 file we were just testing it all right now we're

were just testing it all right now we're actually going to play the clip

actually going to play the clip now one last thing that I'm going to add

now one last thing that I'm going to add it's optional I'm going to add a finally

it's optional I'm going to add a finally block once we're done with this program

block once we're done with this program we can output the following let's just

we can output the following let's just say

say by this will make sense in just a moment

by this will make sense in just a moment why I'm doing this there's one problem

why I'm doing this there's one problem we're going to encounter when we play

we're going to encounter when we play our audio now to actually play the audio

our audio now to actually play the audio we're going to take our clip

we're going to take our clip object call the start method to start

object call the start method to start the

the audio here's what happens when I run

audio here's what happens when I run this currently

the music may play for just a brief second we print by then exit the program

second we print by then exit the program right away the issue that we're running

right away the issue that we're running into is that our program doesn't wait

into is that our program doesn't wait for the audio to finish once we start

for the audio to finish once we start the clip we immediately end the

the clip we immediately end the program so we need some way to keep the

program so we need some way to keep the clip open and there's a bunch of

clip open and there's a bunch of different options you could use

different options you could use threading within a while loop to check

threading within a while loop to check to see if the clip is still running but

to see if the clip is still running but I haven't taught that yet so here's

I haven't taught that yet so here's another option we create a prompt for

another option we create a prompt for the user to play stop reset or quit the

the user to play stop reset or quit the audio program the audio will continue

audio program the audio will continue playing unless the user decides to stop

playing unless the user decides to stop or quit the program so we'll need a

or quit the program so we'll need a scanner to work with to accept user

scanner to work with to accept user input scanner scanner equals new scanner

input scanner scanner equals new scanner pass in

system.in import this class now if you open a scanner you do

class now if you open a scanner you do want to close it when you're done with

want to close it when you're done with it you can do that within the final

it you can do that within the final finally block like this scanner.

finally block like this scanner. close with modern Java you can use try

close with modern Java you can use try with resources which will automatically

with resources which will automatically close any resources and we can do that

close any resources and we can do that with our scanner too let's cut our

with our scanner too let's cut our scanner paste it within the tri block

scanner paste it within the tri block now be sure to include the

now be sure to include the semicolon our scanner is going to

semicolon our scanner is going to automatically close when we're done with

automatically close when we're done with this program because we're using try

this program because we're using try with resources you can use try with

with resources you can use try with resources if an object implements the

resources if an object implements the autoc closable interface scanner and

autoc closable interface scanner and audio stream both do clip doesn't so

audio stream both do clip doesn't so we'll keep that within the tri block

we'll keep that within the tri block rather than start our clip let's create

rather than start our clip let's create a string variable of

a string variable of response we'll create a while

response we'll create a while loop while our

loop while our response

response equals let's say capital Q now we want

equals let's say capital Q now we want to say while our response doesn't equal

to say while our response doesn't equal capital Q we'll use the Notch logical

capital Q we'll use the Notch logical operator and to make our while loop

operator and to make our while loop happy we do have to initialize our

happy we do have to initialize our response we'll set that to be an empty

response we'll set that to be an empty string so a user is going to type in a

string so a user is going to type in a response as long as it's not Q meaning

response as long as it's not Q meaning quit we'll continue the

quit we'll continue the program within the while loop we'll give

program within the while loop we'll give a user a few

a user a few options let's output the

options let's output the following let's say p equals

following let's say p equals play Let's copy this print line

play Let's copy this print line statement s equals

statement s equals stop R is to

quit then we will ask a user to enter your choice I'll use print rather than

your choice I'll use print rather than print line to keep the user input on the

print line to keep the user input on the same

same line we'll take our response which is a

line we'll take our response which is a string set it equal to use our scanner

string set it equal to use our scanner get the next character by calling the

get the next character by calling the next method in case a user types in a

next method in case a user types in a lowercase character we can make it

lowercase character we can make it uppercase by Method chaining the two

uppercase by Method chaining the two uppercase

uppercase method all right we'll do a test run and

method all right we'll do a test run and let's be sure that we start the clip

let's be sure that we start the clip just temporarily clip.art method what's

just temporarily clip.art method what's likely going to happen is that we'll

likely going to happen is that we'll start the audio clip and it won't stop

start the audio clip and it won't stop until we press Q to quit

so here's the audio hopefully you can hear me once I press Q the program's

hear me once I press Q the program's going to

going to stop it's because the program closes

stop it's because the program closes down and

down and exits now we want to give the user a few

exits now we want to give the user a few options after they type in their

options after they type in their response we can use an enhanced switch

response we can use an enhanced switch for this let's also be sure that we

for this let's also be sure that we delete the start method of our

clip we don't want the audio clip to start until the user presses p to play

start until the user presses p to play we will create a

we will create a switch we will examine our

switch we will examine our response does our response match any

response does our response match any cases if our response matches a case of

cases if our response matches a case of P we'll write an arrow to do the

P we'll write an arrow to do the following take our clip then call the

following take our clip then call the start

start method if our response matches a case of

method if our response matches a case of s that means stop take our clip object

s that means stop take our clip object called the stop method

called the stop method if our response matches a case of R do

if our response matches a case of R do the following take our clip to reset

the following take our clip to reset you're going to call the set

you're going to call the set micro

micro second

second position then pass in

position then pass in zero do pay attention to the

zero do pay attention to the capitalization s is a

capitalization s is a lowercase if our response matches a case

lowercase if our response matches a case of Q take our clip call the close method

of Q take our clip call the close method to close the clip

to close the clip then if there's no matching cases let's

then if there's no matching cases let's output the

output the following system.out.print line invalid

everything enter your choice just to be sure that the default case is working

sure that the default case is working I'm going to type

I'm going to type Taco invalid Choice we'll press P to

Taco invalid Choice we'll press P to play

s to stop P to play

stop P to play again R to

again R to reset and Q to

reset and Q to [Music]

[Music] quit all right everybody that is an

quit all right everybody that is an audio player that you can write using

audio player that you can write using Java what's up everybody in this video

Java what's up everybody in this video we're going to create a working game of

we're going to create a working game of hangman using Java a user is going to

hangman using Java a user is going to guess certain characters and we'll see

guess certain characters and we'll see if there's a match within a secret word

if there's a match within a secret word near the end of this video topic will be

near the end of this video topic will be importing a file of words and one of

importing a file of words and one of those words will be secretly selected so

those words will be secretly selected so let's get started all right let's get

let's get started all right let's get started everybody near the end of this

started everybody near the end of this video we'll have our program choose a

video we'll have our program choose a random word from a list of words but to

random word from a list of words but to keep this program simple in the

keep this program simple in the beginning for a testing purposes let's

beginning for a testing purposes let's create a string variable of word here

create a string variable of word here we'll select a word that we're going to

we'll select a word that we're going to use throughout the program just for

use throughout the program just for testing pick a word for me I'll say you

testing pick a word for me I'll say you know what let's go with pizza so this

know what let's go with pizza so this will be my word so we have our word

will be my word so we have our word we'll be accepting user input so we need

we'll be accepting user input so we need a scanner scanner scanner equals new

a scanner scanner scanner equals new scanner pass in

scanner pass in system.in import the scanner class and

system.in import the scanner class and close your scanner at the end of the

close your scanner at the end of the program scanner.

program scanner. close here's where we'll be working with

close here's where we'll be working with array lists we will create an array list

array lists we will create an array list of characters to do that we type array

of characters to do that we type array list then specify the type within a set

list then specify the type within a set of angle brackets we can't use

of angle brackets we can't use Primitives such as Char we'll have to

Primitives such as Char we'll have to use the rapper class of character to

use the rapper class of character to store characters I will name this array

store characters I will name this array list word State equals a

list word State equals a new array list use the diamond operator

new array list use the diamond operator set of parenthesis semicolon we'll need

set of parenthesis semicolon we'll need to import this

class now within the diamond operator you don't need to list character again

you don't need to list character again even though that does work Java can

even though that does work Java can infer what the type is in the beginning

infer what the type is in the beginning our word state is going to contain a

our word state is going to contain a bunch of underscores and we're going to

bunch of underscores and we're going to fill them in one letter at a time by

fill them in one letter at a time by guessing we'll also need a variable to

guessing we'll also need a variable to keep track of our wrong guesses int

keep track of our wrong guesses int wrong

wrong guesses this will initially be zero

guesses this will initially be zero we'll set that equal to be

we'll set that equal to be zero within our array of word State

zero within our array of word State we're going to add an underscore for

we're going to add an underscore for every letter within our word we'll

every letter within our word we'll create a for Loop that will cycle once

create a for Loop that will cycle once for every letter in our word here's how

for every letter in our word here's how we can do that

we can do that so we'll start with a basic for Loop

so we'll start with a basic for Loop create an INT of I for index equals 0

create an INT of I for index equals 0 we'll continue as long as I is less than

we'll continue as long as I is less than take our word and strings have a

take our word and strings have a built-in length method return the length

built-in length method return the length of this word so in this case it's going

of this word so in this case it's going to be five because there's five letters

to be five because there's five letters in this word then increment I by One

in this word then increment I by One during each cycle of this for loop we're

during each cycle of this for loop we're going to take our array of word State

going to take our array of word State and and add a character by using the add

and and add a character by using the add method we will pass in an underscore an

method we will pass in an underscore an underscore character be sure you're

underscore character be sure you're using single quotes not double quotes

using single quotes not double quotes because these are chars technically not

because these are chars technically not strings all right let's do a test run

strings all right let's do a test run I'm going to Output our word state to

I'm going to Output our word state to see what we have so we should get 5core

see what we have so we should get 5core characters and we do one 2 3 four five p

characters and we do one 2 3 four five p i z z a throughout this game by guessing

i z z a throughout this game by guessing letters we'll be filling in this word

letters we'll be filling in this word state by replacing the underscores if

state by replacing the underscores if there's a

there's a match let's change this word just so we

match let's change this word just so we know that everything's working I will

know that everything's working I will pick watermelon because that's the first

pick watermelon because that's the first thing that came to mind so watermelon

thing that came to mind so watermelon has 10

has 10 characters 1 2 3 4 5 6 7 8 9 10 all

characters 1 2 3 4 5 6 7 8 9 10 all right we know that that works I will

right we know that that works I will switch it back to Pizza delete this

switch it back to Pizza delete this print statement and we can move

print statement and we can move on word state is an array list made up

on word state is an array list made up of characters currently they're all

of characters currently they're all underscores but we'll be replacing each

underscores but we'll be replacing each with the character if we get the correct

with the character if we get the correct guess after the for Loop why don't we

guess after the for Loop why don't we create a welcome

create a welcome message let's say welcome to Java

message let's say welcome to Java hangman now you don't need to do this

hangman now you don't need to do this but I'm going to add some decorators

but I'm going to add some decorators just a bunch of asterisks before and

just a bunch of asterisks before and after again you don't need to but I

after again you don't need to but I think it looks

cool let's make sure everything looks okay welcome to Java

hangman for our hangman we're going to display some asky art outside of our

display some asky art outside of our main method we're going to declare

main method we're going to declare another method that's in charge of

another method that's in charge of returning asky art based on the number

returning asky art based on the number of wrong guesses that we have this will

of wrong guesses that we have this will be a static method it's going to return

be a static method it's going to return a string we'll name this method get

a string we'll name this method get hangman

hangman art we will have one parameter we have

art we will have one parameter we have to pass in how many wrong guesses we

to pass in how many wrong guesses we have then depending on the number of

have then depending on the number of wrong guesses we'll return a certain

wrong guesses we'll return a certain image represented as a

image represented as a string within our get hangman art method

string within our get hangman art method we'll be returning a string a string

we'll be returning a string a string representation of our asky art we can

representation of our asky art we can best do this with the switch now a

best do this with the switch now a switch can return something we'll use

switch can return something we'll use the return keyword create a

the return keyword create a switch end it with a semicolon within

switch end it with a semicolon within our switch what are we examining we're

our switch what are we examining we're examining the number of wrong guesses

examining the number of wrong guesses this will be a number 0 through 6 we'll

this will be a number 0 through 6 we'll need a case for each of those numbers

need a case for each of those numbers for each of those guesses depending on

for each of those guesses depending on how many wrong guesses the user has

how many wrong guesses the user has we'll display one of a few images so

we'll display one of a few images so here we'll be working on our art skills

here we'll be working on our art skills today too if we have a matching case

today too if we have a matching case where wrong guesses matches a case of

where wrong guesses matches a case of zero that means they have no wrong

zero that means they have no wrong guesses

guesses case0 Arrow meaning do this will return

case0 Arrow meaning do this will return the following in Java you can write a

the following in Java you can write a multi-line string but you have to use a

multi-line string but you have to use a triple set of double quotes and I'm just

triple set of double quotes and I'm just going to line these

going to line these up within this triple set of double

up within this triple set of double quotes I'll have three empty lines

quotes I'll have three empty lines between

between them we won't display anything if the

them we won't display anything if the number of wrong guesses is

number of wrong guesses is zero then for case one if a user has one

zero then for case one if a user has one wrong

wrong guess we'll display our man's

guess we'll display our man's head represented by an

head represented by an O if wrong guesses is two we can

O if wrong guesses is two we can represent that with case two we will

represent that with case two we will draw the man's

draw the man's body represented by a vertical

body represented by a vertical bar case three will be the left

arm for the left arm we'll use a forward slash for case four

that will be for the right arm we'll use a backslash in Java a backslash is

a backslash in Java a backslash is actually an escape sequence to display a

actually an escape sequence to display a backslash we have to use double back

backslash we have to use double back slashes case five will be for the left

leg it's kind of like we're assembling Exodia if you know the

Exodia if you know the reference and then k6 is for the right

reference and then k6 is for the right leg we'll need two backs

leg we'll need two backs slashes we'll want to a default case if

slashes we'll want to a default case if there's no matching

there's no matching cases we'll just return an empty string

cases we'll just return an empty string just to make Java happy all right and

just to make Java happy all right and this method is done based on the number

this method is done based on the number of wrong guesses we'll return one of a

of wrong guesses we'll return one of a few

strings Let's test it I'm going to use a print line

print line statement call our get hangman art

statement call our get hangman art method we'll start with zero zero wrong

method we'll start with zero zero wrong guesses we should end up displaying

guesses we should end up displaying three empty lines

if wrong guesses is one we should display The Hangman's

display The Hangman's head

head two two is for the

two two is for the body three is for the left

arm four is for the right

four is for the right arm five is for the left leg

body that's when we lose when wrong guesses is six all right we know that

guesses is six all right we know that the get hangman art method works I will

the get hangman art method works I will collapse it because we're done with it

collapse it because we're done with it to get the art for our hangman we just

to get the art for our hangman we just have to call this method then pass in

have to call this method then pass in the current number of wrong guesses

the current number of wrong guesses let's delete this print line statement

let's delete this print line statement we no longer need

we no longer need it now when we print our word

it now when we print our word State let me show you

State let me show you we get this ugly formatting where we

we get this ugly formatting where we have a set of straight brackets then all

have a set of straight brackets then all the underscores are comma separated we

the underscores are comma separated we can customize that so here's what we'll

can customize that so here's what we'll do after our welcome message we'll

do after our welcome message we'll output the

following we'll output the word word colon space I'll use print I want to

colon space I'll use print I want to stay on the same line we'll create a for

stay on the same line we'll create a for Loop an enhanced for Loop

Loop an enhanced for Loop for every character in our array list of

for every character in our array list of word State we're going to display an

word State we're going to display an underscore with no

underscore with no formatting using an enhanced for Loop we

formatting using an enhanced for Loop we have to list the data type of what we're

have to list the data type of what we're cycling through we're cycling through an

cycling through we're cycling through an array of characters Char a common

array of characters Char a common convention with enhanced for Loops is to

convention with enhanced for Loops is to name each letter C because we can't use

name each letter C because we can't use Char because that's a data

Char because that's a data type and character is kind of long so C

type and character is kind of long so C is short for character for every

is short for character for every character of C

character of C in our array list our array list is

in our array list our array list is named word

named word State we'll do the

State we'll do the following we will output our character

following we will output our character of C plus a

of C plus a space so then when we output

space so then when we output this oh let's use print rather than

this oh let's use print rather than print line because we want them all in

print line because we want them all in the same

line that's much better that output looks a lot nicer each letter letter is

looks a lot nicer each letter letter is an underscore they're all separated with

an underscore they're all separated with a space when we guess each letter we'll

a space when we guess each letter we'll be flipping these underscores to its

be flipping these underscores to its matching character if they do

matching character if they do match I'll add an empty print line just

match I'll add an empty print line just so we go down to the next

so we go down to the next line okay for the next part we'll have a

line okay for the next part we'll have a user guess a letter we'll need some user

user guess a letter we'll need some user input we'll need a

input we'll need a prompt guess a letter colon space I'll

prompt guess a letter colon space I'll use print not print line

use print not print line we'll create a variable of guess guess

we'll create a variable of guess guess will be a

will be a letter we'll need to accept user input

letter we'll need to accept user input we'll need to accept user input using

we'll need to accept user input using our scanner scanner. next next will get

our scanner scanner. next next will get the next

the next character now since we're working with

character now since we're working with lowercase characters we can method chain

lowercase characters we can method chain the two lowercase method just to make it

the two lowercase method just to make it lowercase if somebody types in an

lowercase if somebody types in an uppercase character to lower case

okay to lowercase method using next the user input is going to be a string not a

user input is going to be a string not a character we can easily convert that to

character we can easily convert that to a character by using the Char at

a character by using the Char at method but we have to pass it an index

method but we have to pass it an index we're only accepting a single character

we're only accepting a single character so we'll use Char at zero we're telling

so we'll use Char at zero we're telling Java with the string that the user types

Java with the string that the user types in give me just the first character and

in give me just the first character and convert it to be a Char so guess is

convert it to be a Char so guess is going to be a single letter it'll be of

going to be a single letter it'll be of the Char data type

the Char data type all right then let's test it I will

all right then let's test it I will output our

guess I will guess an uppercase P we'll end up outputting a lowercase p

P we'll end up outputting a lowercase p which is

which is good how about a z yep our guess is z if

good how about a z yep our guess is z if I were to type in a full word like

I were to type in a full word like pineapple we still end up with just the

pineapple we still end up with just the first character the first character in

first character the first character in our

our string which is good though let's delete

string which is good though let's delete this print line statement we no longer

this print line statement we no longer need it for this next part we're going

need it for this next part we're going to check to see if our guess matches any

to check to see if our guess matches any letters within our

letters within our word we'll use an if statement for

word we'll use an if statement for that if take our word it's a string in

that if take our word it's a string in this case Pizza we'll use the built-in

this case Pizza we'll use the built-in index of

index of method and then pass in our

method and then pass in our guess so basically with the index of

guess so basically with the index of method it's going to return the index

method it's going to return the index within the string of the first

within the string of the first occurrence of the specified

occurrence of the specified character for example let's say I guess

character for example let's say I guess the letter Z well Z is in the word Pizza

the letter Z well Z is in the word Pizza it's at index 2 that's the first

it's at index 2 that's the first occurrence if my guess was Z index of is

occurrence if my guess was Z index of is going to return the number two because

going to return the number two because that's the first occurrence of Z we will

that's the first occurrence of Z we will check if the first occurrence is greater

check if the first occurrence is greater than or equal to zero that means there's

than or equal to zero that means there's a matching letter if that's the

a matching letter if that's the case if there's a matching letter well

case if there's a matching letter well will

will output

output correct guess and then I'm just going to

correct guess and then I'm just going to add a new line character to the

add a new line character to the end all right let's do a test

end all right let's do a test run I will guess the letter Z that's a

run I will guess the letter Z that's a correct

correct guess but are there any

guess but are there any X's there is not so we don't output

X's there is not so we don't output correct

correct guess if it's the wrong guess we can

guess if it's the wrong guess we can output using an lse statement

output using an lse statement wrong guess then I'll add a new line

wrong guess then I'll add a new line character to the end let's try that

character to the end let's try that again I will guess an X wrong

again I will guess an X wrong guess there are no x's in the word

guess there are no x's in the word Pizza okay so within our if statement if

Pizza okay so within our if statement if we get the correct guess we're going to

we get the correct guess we're going to change our word state to reflect

change our word state to reflect it that's one less letter that the user

it that's one less letter that the user has to

has to guess we're going to cycle through the

guess we're going to cycle through the length of our word using a for Loop for

length of our word using a for Loop for in I equals 0 we'll continue as long as

in I equals 0 we'll continue as long as I is less than our words length by

I is less than our words length by calling the length method then increment

calling the length method then increment I by

I by one we have to see where there's a match

one we have to see where there's a match exactly which index within our word

exactly which index within our word we'll use an if

we'll use an if statement we will take our word in this

statement we will take our word in this case Pizza called the Char at method

case Pizza called the Char at method then pass in our index of I during each

then pass in our index of I during each cycle I is going to increment but during

cycle I is going to increment but during the first cycle it's going to be zero so

the first cycle it's going to be zero so we're saying take our word in this

we're saying take our word in this example Pizza give me the first

example Pizza give me the first character so for pizza that would be the

character so for pizza that would be the letter

letter P is that equal to using the comparison

P is that equal to using the comparison operator are

operator are guess so let's say I do guess P the

guess so let's say I do guess P the first character of my word is P that

first character of my word is P that means that they match we're going to

means that they match we're going to take our array list of word State and

take our array list of word State and we're going to update it by using the

we're going to update it by using the set

set method we have to pass in an index and a

method we have to pass in an index and a new value our

new value our guess let's test

guess let's test it so with the word Pizza are there any

it so with the word Pizza are there any z's correct guess oh then we have to

z's correct guess oh then we have to Output it

Output it too we're going to continue playing as

too we're going to continue playing as long as wrong guesses is less than six

long as wrong guesses is less than six once wrong guesses is six or greater

once wrong guesses is six or greater then the game

then the game ends so so let's cut this portion of

ends so so let's cut this portion of code cut it don't delete it we'll write

code cut it don't delete it we'll write a while

a while loop

loop while our wrong guesses variable wrong

while our wrong guesses variable wrong guesses is less than six we'll continue

guesses is less than six we'll continue playing this game within the while loop

playing this game within the while loop we'll paste all that code again let's do

we'll paste all that code again let's do a test

run guess a letter I'm going to guess Z so that should update our word to

so that should update our word to reflect two Z's because my word is pizza

reflect two Z's because my word is pizza but if there's no matching

but if there's no matching letters it doesn't get updated because

letters it doesn't get updated because there's no matches let me fill this in p

there's no matches let me fill this in p i ZZ a and we get the full word all

i ZZ a and we get the full word all right that's good so far so

right that's good so far so good so we'll need to keep track of

good so we'll need to keep track of wrong guesses within our else statement

wrong guesses within our else statement we're going to take our variable of

we're going to take our variable of wrong guesses incremented by one using

wrong guesses incremented by one using the increment operator

the increment operator then back to the beginning of the loop

then back to the beginning of the loop we're going to display our hangman art

we're going to display our hangman art by calling the get hangman art

by calling the get hangman art method this method will return a string

method this method will return a string so we can put that within a print

so we can put that within a print statement let's use print call the get

statement let's use print call the get hangman art method then pass in the

hangman art method then pass in the number of wrong

number of wrong guesses let's do another test

guesses let's do another test run we have three empty spaces because

run we have three empty spaces because we haven't displayed any parts of the

we haven't displayed any parts of the hangman yet I will guess the wrong

hangman yet I will guess the wrong letter X we get the head of the hangman

letter X we get the head of the hangman I'll guess some more wrong

I'll guess some more wrong letters

letters CV b n

m at the end we'll have to display the full hangman when we

full hangman when we lose let's display the right

lose let's display the right letters p i z

letters p i z a okay good what happens when we lose if

a okay good what happens when we lose if wrong guesses is six or

wrong guesses is six or greater so outside of the while loop our

greater so outside of the while loop our while loop ends right

while loop ends right here we'll write an if

here we'll write an if statement if our variable of wrong

statement if our variable of wrong guesses is greater than or equal to

guesses is greater than or equal to six okay we will again use a print

six okay we will again use a print statement called the get hangman art

statement called the get hangman art method and then pass in the number of

method and then pass in the number of wrong

wrong guesses we'll also display a game over

guesses we'll also display a game over message game

message game over then display the

over then display the word the word

word the word was colon space plus our original word

was colon space plus our original word of

of pizza let's do a test run

pizza let's do a test run again I'm going to guess the wrong

characters all right game over we display the the full hangman the word

display the the full hangman the word was

was pizza I think I'm going to make a few

pizza I think I'm going to make a few changes I'm going to remove these new

changes I'm going to remove these new line

line characters it's a little too much space

characters it's a little too much space I

I think all right we're

think all right we're good so how do we win let's add that

good so how do we win let's add that after the for

after the for Loop if we get a correct guess we'll

Loop if we get a correct guess we'll check to see if our word State doesn't

check to see if our word State doesn't contain any lowercase

contain any lowercase characters so take our array list of

characters so take our array list of word

word State call the contains

State call the contains method and then pass in an underscore

method and then pass in an underscore character but we want to check to see if

character but we want to check to see if our word State doesn't contain any

our word State doesn't contain any lowercase characters we can prefix this

lowercase characters we can prefix this with the not logical operator an

with the not logical operator an exclamation point if our word our word

exclamation point if our word our word State doesn't contain any lowercase

State doesn't contain any lowercase characters that means that we guessed

characters that means that we guessed all the letters and we

all the letters and we win if that's true let's display our

win if that's true let's display our hangman One Last Time

hangman One Last Time system.out.print get hangman art pass in

system.out.print get hangman art pass in the number of wrong guesses and we'll

the number of wrong guesses and we'll display you

again the word was colon space plus our word then we'll want to break out of

word then we'll want to break out of this Loop cuz we're stuck in a while

this Loop cuz we're stuck in a while loop we can use a break statement after

loop we can use a break statement after we win to break out of the

loop all right let's see what we're working

with I'll guess a few wrong letters x c v b n all right one more wrong guess and

v b n all right one more wrong guess and I lose game over the word was

I lose game over the word was pizza all right I'll actually win this

pizza all right I'll actually win this time but I'll guess a few wrong

time but I'll guess a few wrong characters q

characters q w t

w t I'll guess some correct characters a z i

I'll guess some correct characters a z i p you win and we display our current

p you win and we display our current score the current state of our hangman

score the current state of our hangman we display you win the word was

we display you win the word was pizza in this next part of this video

pizza in this next part of this video we're going to create a more advanced

we're going to create a more advanced version of this program by importing a

version of this program by importing a file of words a word is going to be

file of words a word is going to be randomly chosen from a file instead of

randomly chosen from a file instead of just setting one in the beginning okay

just setting one in the beginning okay everybody in this next section we're

everybody in this next section we're going to create a file that contains all

going to create a file that contains all the words that we can possibly use for

the words that we can possibly use for this Hangman game within our project

this Hangman game within our project folder why don't we create a new file

folder why don't we create a new file file new file I'm going to name this

file new file I'm going to name this file words and this will be a txt

file words and this will be a txt file for all the different possible

file for all the different possible words in this game place within this

words in this game place within this file you can copy and paste them from

file you can copy and paste them from somewhere online if you would like just

somewhere online if you would like just to make reading this file a simple as

to make reading this file a simple as possible I'm going to list all the words

possible I'm going to list all the words on a separate line so think of some

on a separate line so think of some words or like I said copying paste them

words or like I said copying paste them from somewhere I'll just add several

from somewhere I'll just add several Apple orange banana

Apple orange banana coconut

coconut pineapple grape lime lemon that's good

pineapple grape lime lemon that's good enough in my project folder I have this

enough in my project folder I have this file words.txt

file words.txt temporarily with my game I'm going to

temporarily with my game I'm going to write a multiline comment and just

write a multiline comment and just comment all of this out until we're

comment all of this out until we're ready to bring it back in

at the top of my Hangman game I will create a string named file

create a string named file path this will contain either a relative

path this will contain either a relative file path or an absolute file path since

file path or an absolute file path since this file is in my project folder I just

this file is in my project folder I just have to list the file name words.txt

we're going to read this file line by line we'll store each word in an array

line we'll store each word in an array list we'll create a new array list AR

list we'll create a new array list AR array list the data type is Going to Be

array list the data type is Going to Be Strings so string I will name this array

Strings so string I will name this array list words equals new array list Diamond

list words equals new array list Diamond operator parenthesis

operator parenthesis semicolon now we'll actually need to

semicolon now we'll actually need to read this file reading files is

read this file reading files is considered dangerous code because it's

considered dangerous code because it's highly likely that something can go

highly likely that something can go wrong we will write a try with resources

wrong we will write a try with resources block we need that set of parentheses

block we need that set of parentheses after try we will catch any except

after try we will catch any except options when you try with resources

options when you try with resources you'll automatically close any resources

you'll automatically close any resources listed within the set of parentheses

listed within the set of parentheses within the set of parentheses we will

within the set of parentheses we will create a buffered reader

create a buffered reader object buffered reader which we will

object buffered reader which we will name reader for short equals new

name reader for short equals new buffered

reader now a buffered reader by itself can't read files we do have to pass in a

can't read files we do have to pass in a file reader to the Constructor

file reader to the Constructor new file reader then within our file

new file reader then within our file reader Constructor we will pass in our

reader Constructor we will pass in our file path the location to that

file path the location to that file now our file reader object wants us

file now our file reader object wants us to catch any file not found

to catch any file not found exceptions we'll place that within our

exceptions we'll place that within our catch block file not found exception of

catch block file not found exception of e then we'll output if we can't find

e then we'll output if we can't find this

this file could not find

file could not find file We'll add another catch block just

file We'll add another catch block just as a safety net we'll catch any

as a safety net we'll catch any IO

IO exception e

exception e exceptions this is where we'll say

exceptions this is where we'll say something went wrong this just acts as a

something went wrong this just acts as a safety net if there's something we don't

safety net if there's something we don't anticipate so we have our reader object

anticipate so we have our reader object within the tri block we will create a

within the tri block we will create a local variable it's a string of

local variable it's a string of line we will read this file line by line

line we will read this file line by line using a while

using a while loop while within a set of parentheses

loop while within a set of parentheses assign our line equal to use our reader

assign our line equal to use our reader called the read line

called the read line method if we run out of lines this is

method if we run out of lines this is going to return null while the value

going to return null while the value that's returned does not equal null

that's returned does not equal null we'll continue reading this file reader

we'll continue reading this file reader is going to give us each of these words

is going to give us each of these words line by line we're going to assign them

line by line we're going to assign them to our array list of words take our

to our array list of words take our array list of words call the add method

array list of words call the add method we will add the current

we will add the current line if there's any white space after

line if there's any white space after these words this will pick that up and

these words this will pick that up and our program will consider them to be

our program will consider them to be characters we will use the trim method

characters we will use the trim method after line to trim that white

space let's perform a test run I'm going to Output our array list of words

to Output our array list of words yep and here's our words all within an

yep and here's our words all within an array

array list let's delete that line we're going

list let's delete that line we're going to choose one of these words at random

to choose one of these words at random we'll need a random object random random

we'll need a random object random random equals new

equals new random import the

random import the class here's where we're going to choose

class here's where we're going to choose our word I'm going to copy this from the

our word I'm going to copy this from the previous

previous code and paste

code and paste it rather than setting our word to be

it rather than setting our word to be hard-coded string we're going to take

hard-coded string we're going to take our array list of

words call the get method but we have to specify an

method but we have to specify an index with our array list return a

index with our array list return a string at a given index that index is

string at a given index that index is going to be randomly generated by using

going to be randomly generated by using this random object we will pass in a

this random object we will pass in a random object call the next int method

random object call the next int method to generate a random integer the range

to generate a random integer the range of random numbers is going to be

of random numbers is going to be dependent on the size of our array list

dependent on the size of our array list of

of words take our words call the size

words take our words call the size method so with our file I have let's see

method so with our file I have let's see how many words how many strings 1 2 3 4

how many words how many strings 1 2 3 4 5 6 7

5 6 7 8 the size method of words is going to

8 the size method of words is going to return the number eight just imagine

return the number eight just imagine that I'm replacing this with the number

that I'm replacing this with the number eight return a random index between 0

eight return a random index between 0 and 8 that's kind of how that works and

and 8 that's kind of how that works and then let's output our word for testing

then let's output our word for testing purposes

what is my word this time my word was pineapple but

word this time my word was pineapple but it's likely going to change every time

it's likely going to change every time you run it Apple lime Apple again

you run it Apple lime Apple again pineapple

pineapple grape it really likes pineapple for some

grape it really likes pineapple for some reason let's delete this print line

reason let's delete this print line statement we'll integrate our code back

statement we'll integrate our code back into the program again we can delete

into the program again we can delete that multi-line

comment and let's R this program one last time we should now have a randomly

last time we should now have a randomly chosen

chosen word I don't know what it's going to be

word I don't know what it's going to be for me it's six letters I'll guess some

for me it's six letters I'll guess some of the vowels a there's one a e i o

of the vowels a there's one a e i o u it's probably orange but I'm going to

u it's probably orange but I'm going to guess some more wrong letters for

guess some more wrong letters for testing

testing purposes okay game

purposes okay game over the word was Orange let's run it

over the word was Orange let's run it again

again this one is seven

this one is seven letters a e i o u it's

letters a e i o u it's coconut

coconut Co n u t you win the word was

Co n u t you win the word was coconut all right everybody that is a

coconut all right everybody that is a game of hangman that you can code using

game of hangman that you can code using Java hello there everybody in this video

Java hello there everybody in this video I'm going to show you how we can work

I'm going to show you how we can work with dates and times using Java this

with dates and times using Java this serves as more of an introduction we can

serves as more of an introduction we can work with local dates times date times

work with local dates times date times and UTC timestamps let's get the date

and UTC timestamps let's get the date right now using local date we will

right now using local date we will create an object of local date let's

create an object of local date let's name this date for short

name this date for short equals access the class of local

equals access the class of local date called the now

date called the now method if I was to Output our date

method if I was to Output our date object we'll print our date that's going

object we'll print our date that's going to give you the current date whatever it

to give you the current date whatever it is right now I'm filling this video

is right now I'm filling this video December 17th

December 17th 2024 post the date that you're watching

2024 post the date that you're watching this in the comment section down below

this in the comment section down below that is local date there's local time to

that is local date there's local time to get the time let's replace date with

get the time let's replace date with time local time.

time local time. now and rename this as time cuz that's

now and rename this as time cuz that's more

more appropriate print the time currently the

appropriate print the time currently the time for me is a little after 9:00 a.m.

time for me is a little after 9:00 a.m. 9 hours 29 minutes 52 seconds

9 hours 29 minutes 52 seconds and a bunch of

and a bunch of milliseconds to retrieve both the date

milliseconds to retrieve both the date and the time you can use date time local

and the time you can use date time local date

time local dat time.now method print the current date

current date time and currently for me it is December

time and currently for me it is December 17th 2024 at about 9:30 in the

17th 2024 at about 9:30 in the morning you can also use UTC time that's

morning you can also use UTC time that's a little different we will create a

a little different we will create a instant object instant instant equals

instant object instant instant equals access the class of instant called the

access the class of instant called the now

now method and print our instant

method and print our instant object which will give us the current

object which will give us the current date and time in

date and time in UTC December 17th 2024 in UTC time I

UTC December 17th 2024 in UTC time I think that's 300 p.m. it's in military

think that's 300 p.m. it's in military time that's how to get either the

time that's how to get either the current date time date time or UTC

current date time date time or UTC timestamp when you output the current

timestamp when you output the current date and/ or time it's kind of ugly and

date and/ or time it's kind of ugly and hard to read well we can write a custom

hard to read well we can write a custom format to display our date time here's

how here we'll create a custom format for our date time we will need the

for our date time we will need the current date

current date time local date

time local date time we will name this date time equals

time we will name this date time equals access the class of local date time

access the class of local date time called the now method

called the now method then we'll need to create a formatter

then we'll need to create a formatter object date time

object date time formatter we'll name this formatter

formatter we'll name this formatter equals date time formatter I'm just

equals date time formatter I'm just going to copy it call the of pattern

going to copy it call the of pattern method and then we're going to pass on a

method and then we're going to pass on a string let me move the cursor so you can

string let me move the cursor so you can see this within the string we will write

see this within the string we will write pattern letters what is the pattern in

pattern letters what is the pattern in which we would like to display our date

which we would like to display our date and our time if you go to the official

and our time if you go to the official Java documentation there's an extensive

Java documentation there's an extensive list here's a few beginner friendly ones

list here's a few beginner friendly ones for the day type 2DS dash for the month

for the day type 2DS dash for the month two Capital M's for the year Das y y y y

two Capital M's for the year Das y y y y four

four y's this will display the day the month

y's this will display the day the month and the year I'm an American so we

and the year I'm an American so we display the month first followed by the

display the month first followed by the day so I'm going to switch this around

day so I'm going to switch this around but you can keep it as it originally was

but you can keep it as it originally was if you prefer so that's how to display

if you prefer so that's how to display the date in that

the date in that format month day year now for the time

format month day year now for the time you can do the following for hours do

you can do the following for hours do two Capital H's colon minutes is two

two Capital H's colon minutes is two lowercase M's colon then for seconds

lowercase M's colon then for seconds it's two lowercase s's that is a good

it's two lowercase s's that is a good pattern we will create a new

pattern we will create a new string named new date

string named new date time equals take our current date time

time equals take our current date time it's an object call the format method

it's an object call the format method we are going to pass in our formatter to

we are going to pass in our formatter to format our date time to this

format our date time to this pattern once we have our new date time

pattern once we have our new date time we're going to print it let's output our

we're going to print it let's output our new date time and it should be in that

new date time and it should be in that format yeah that looks pretty good

format yeah that looks pretty good December 17th 2024 about 9:00 in the

December 17th 2024 about 9:00 in the morning 9:30 at least for me instead of

morning 9:30 at least for me instead of getting the time and date right now we

getting the time and date right now we can create a custom date time object

can create a custom date time object here's how so we'll start with a local

here's how so we'll start with a local date local date I'll name this object

date local date I'll name this object date equals local date we're accessing

date equals local date we're accessing the class statically we'll call the of

the class statically we'll call the of method depending on the date you would

method depending on the date you would like to create we'll pass them in as

like to create we'll pass them in as arguments let's say I would like to pick

arguments let's say I would like to pick Christmas of

Christmas of 2024 the first argument corresponds to

2024 the first argument corresponds to the year I will pick

the year I will pick 2024 the next is for the month 12

2024 the next is for the month 12 meaning

meaning December then the 25th 25th of December

December then the 25th 25th of December I'll type in

I'll type in 25 all right just to test it I'm going

25 all right just to test it I'm going to Output it let's print our

25th you can also use date time let's switch local date to local date

time we need a few more arguments ments so let's say noon on Christmas Day that

so let's say noon on Christmas Day that would be

would be 12 for the minutes 0o for the seconds

12 for the minutes 0o for the seconds zero then let's print this again let's

zero then let's print this again let's output our date well technically it

output our date well technically it should be date time but that still makes

should be date time but that still makes sense here's our date

sense here's our date time December 25th 2024 at noon 12:00

time December 25th 2024 at noon 12:00 p.m. you can also compare dates too

p.m. you can also compare dates too let's copy the snippet of code paste

let's copy the snippet of code paste it rename the first date as date one the

it rename the first date as date one the second date as date two for the second

second date as date two for the second date let's set that to New Year's Day

date let's set that to New Year's Day 2025 the month will be January the 1st

2025 the month will be January the 1st of

of January at midnight that would be

January at midnight that would be zero let's print date one and then date

two so we have Christmas December 25th 2024 and new

Christmas December 25th 2024 and new Year's Day January 1st

Year's Day January 1st 2025 all right now to compare dates we

2025 all right now to compare dates we can use the following we'll use an if

can use the following we'll use an if statement let's check if date

statement let's check if date one called the is before method dates

one called the is before method dates have a built-in is before method pass in

have a built-in is before method pass in date two is date one before date two and

date two is date one before date two and that is

that is true let's output date one plus a string

true let's output date one plus a string of is earlier than plus date 2 let's

of is earlier than plus date 2 let's check that our first date Christmas is

check that our first date Christmas is earlier than New Year's our second

date else if date

if date one let's just copy this date one is

one let's just copy this date one is after date two then we'll output

after date two then we'll output something

something different date one is later than date

different date one is later than date two so let's change date 1 to be January

two so let's change date 1 to be January 2nd of

2025 the second of January is later than New Year's Day our second

New Year's Day our second date you can also check if they're

date you can also check if they're equal let's add else

equal let's add else if let me scroll down date 1 is equal to

if let me scroll down date 1 is equal to date 2

date 2 and then we'll say that they're

and then we'll say that they're equal date 1 is equal

equal date 1 is equal to date

to date two let's set these to be the same New

two let's set these to be the same New Year's Day at

midnight New Year's Day at midnight is equal to New Year's Day at midnight this

equal to New Year's Day at midnight this could be good for some sort of alarm

could be good for some sort of alarm clock checking to see if two date times

clock checking to see if two date times are

are equal all right everybody so that is an

equal all right everybody so that is an introduction to working with dates and

introduction to working with dates and times using

times using Java well hello again friends today I

Java well hello again friends today I got to explain Anonymous classes in Java

got to explain Anonymous classes in Java so what is an anonymous class it's a

so what is an anonymous class it's a class that doesn't have a name meaning

class that doesn't have a name meaning it cannot be reused it's when you want

it cannot be reused it's when you want to add custom Behavior without having to

to add custom Behavior without having to create a new class because it can be

create a new class because it can be really inconvenient to create a new

really inconvenient to create a new class just for one object if that one

class just for one object if that one object is different from the rest in one

object is different from the rest in one way or another they're often used for

way or another they're often used for onetime uses when utilizing features

onetime uses when utilizing features such as timer task the runnable

such as timer task the runnable interface or callbacks these are more

interface or callbacks these are more advanced Java topics so let me

advanced Java topics so let me demonstrate why an anonymous class would

demonstrate why an anonymous class would be useful let's begin with this example

be useful let's begin with this example where we create a dog class file new

where we create a dog class file new Java class we will create a class of

Java class we will create a class of dog let's say that in this dog class

dog let's say that in this dog class there's a single method a speak

there's a single method a speak method void speak all we'll do is I'll

method void speak all we'll do is I'll put the following

put the following the dog goes woof and then let's create

the dog goes woof and then let's create a dog

a dog object dog dog equals new

object dog dog equals new dog we'll take our dog object have it

dog we'll take our dog object have it use its speak method which will

use its speak method which will output the dog goes wo so what if

output the dog goes wo so what if there's a unique kind of dog it's

there's a unique kind of dog it's different from the rest let's say it's

different from the rest let's say it's scoobydoo now

scoobydoo now Scooby-Doo he doesn't speak dog he

Scooby-Doo he doesn't speak dog he speaks English if I want Scooby be do to

speaks English if I want Scooby be do to say something else I'd have to override

say something else I'd have to override this method so one option would be to

this method so one option would be to create a new class again this is me not

create a new class again this is me not using Anonymous classes you'll see their

using Anonymous classes you'll see their usefulness in just a moment let's create

usefulness in just a moment let's create a new Java class let's create a talking

a new Java class let's create a talking dog class I know it's kind of a weird

dog class I know it's kind of a weird example so our talking dog class will

example so our talking dog class will extend the dog class and then we'll

extend the dog class and then we'll override the speak

override the speak method

method override void speak then we'll I'll put

override void speak then we'll I'll put the

the following Scooby Do says what's he

following Scooby Do says what's he usually say rut row or something rut row

usually say rut row or something rut row I think that's how you spell it but you

I think that's how you spell it but you get the idea going back to our main Java

get the idea going back to our main Java file I can create a talking dog object

file I can create a talking dog object talking dog talking dog equals new

talking dog talking dog equals new talking dog that's a lot to

talking dog that's a lot to type and then I can have my talking dog

type and then I can have my talking dog use its speak

method our dog goes woof and Scooby do our talking dog says rutro like uh- oh

our talking dog says rutro like uh- oh it is a lot of work to create a whole

it is a lot of work to create a whole new class just for one unique object our

new class just for one unique object our talking dog of Scooby-Doo is the

talking dog of Scooby-Doo is the exception so rather than creating an

exception so rather than creating an entirely new class just for this one

entirely new class just for this one object just for Scooby-Doo our talking

object just for Scooby-Doo our talking dog let's instead create an anonymous

dog let's instead create an anonymous class we'll take our our talking dog

class we'll take our our talking dog class and delete

it instead of creating a talking dog object let's create another dog object

object let's create another dog object but it's going to have some unique

but it's going to have some unique features that set it apart from other

features that set it apart from other dogs such as the ability to speak

dogs such as the ability to speak English let's rename dog is Dog one

English let's rename dog is Dog one we'll create another dog named dog 2

we'll create another dog named dog 2 equals new dog add aside a parenthesis

equals new dog add aside a parenthesis now to create an anonymous class you're

now to create an anonymous class you're going to add a set of curly

going to add a set of curly braces then make sure there's that

braces then make sure there's that semicolon at the end within the set of

semicolon at the end within the set of curly braces you can Define any unique

curly braces you can Define any unique features or override any methods dog 2

features or override any methods dog 2 is going to be different from all other

is going to be different from all other dogs with it speak method so let's

dogs with it speak method so let's override that method at override void

override that method at override void speak and then we'll

speak and then we'll say Scooby Do

say Scooby Do says rut

says rut row dog one is going to speak and dog

two the dog goes woof Scooby-Doo says rut

rut R so instead of creating an entirely new

R so instead of creating an entirely new class just for one dog Scooby-Doo we can

class just for one dog Scooby-Doo we can create a normal dog and just override

create a normal dog and just override one of the methods using an anonymous

one of the methods using an anonymous class so those are Anonymous classes

class so those are Anonymous classes it's a class that doesn't have a name

it's a class that doesn't have a name and it cannot be reused if you need to

and it cannot be reused if you need to reuse a class you're better off just

reuse a class you're better off just creating a new class it allows you to

creating a new class it allows you to add custom Behavior without having to

add custom Behavior without having to create a new class which is what we did

create a new class which is what we did with the speak method Anonymous classes

with the speak method Anonymous classes are often used with timer task which

are often used with timer task which we'll talk about in the next video the

we'll talk about in the next video the runnable interface and callbacks so it

runnable interface and callbacks so it is an important topic that you need to

is an important topic that you need to know going forward at least to create an

know going forward at least to create an anonymous class after you construct an

anonymous class after you construct an object add a set of curly braces within

object add a set of curly braces within that set of curly braces you can Define

that set of curly braces you can Define new behavior and well everybody those

new behavior and well everybody those are Anonymous classes in Java so uh yeah

are Anonymous classes in Java so uh yeah I got to talk about timers and timer

I got to talk about timers and timer tasks in Java timer is a class that

tasks in Java timer is a class that schedules tasks at specific times or

schedules tasks at specific times or periodically timer is useful for sending

periodically timer is useful for sending notifications scheduled updates or

notifications scheduled updates or repetitive actions when you need to

repetitive actions when you need to schedule a task at a specific time you

schedule a task at a specific time you can use the timer class now timer task

can use the timer class now timer task is the task that's going to execute cute

is the task that's going to execute cute when our timer says so in order to use

when our timer says so in order to use timer task you're going to extend the

timer task you're going to extend the timer task class and then Define your

timer task class and then Define your task and we're going to be doing this by

task and we're going to be doing this by using Anonymous classes which we learned

using Anonymous classes which we learned about in the last video we'll Begin by

about in the last video we'll Begin by creating a timer we need a timer to well

creating a timer we need a timer to well keep track of the time let's say timer

keep track of the time let's say timer timer equals new

timer equals new timer and then import these classes I'm

timer and then import these classes I'm pretty sure you're used to importing

pretty sure you're used to importing these by now

these by now we're going to select the timer from the

we're going to select the timer from the utility

utility package all right we have our timer then

package all right we have our timer then we need a timer task what are we going

we need a timer task what are we going to do when the timer is

up let's just say task timer task task equals new timer task import the

equals new timer task import the class all right so here's the

class all right so here's the situation with our timer class we have

situation with our timer class we have to implement the run method to override

to implement the run method to override the run method we could create a child

the run method we could create a child class from the timer task class but

class from the timer task class but here's a better option we're going to

here's a better option we're going to create an anonymous class after the set

create an anonymous class after the set of parentheses we will add a set of

of parentheses we will add a set of curly braces then add that semicolon to

curly braces then add that semicolon to the end within this Anonymous class we

the end within this Anonymous class we can update or change the behavior of our

can update or change the behavior of our timer task object what we'll do is

timer task object what we'll do is override the run

override the run method

method override to overrun this method

override to overrun this method this will be public void run it's the

this will be public void run it's the run

run method when we execute our task what

method when we execute our task what would we like to do let's output the

would we like to do let's output the following let's just say

following let's just say hello so our task is to print

hello so our task is to print hello but we have to do it when our

hello but we have to do it when our timer says so so they work

timer says so so they work together let's say I would like to say

together let's say I would like to say hello after 3 seconds to do that we're

hello after 3 seconds to do that we're going to take our timer

going to take our timer call the schedule

call the schedule method and then there's two arguments

method and then there's two arguments we're going to pass in our task what are

we're going to pass in our task what are we going to do that's the first argument

we going to do that's the first argument the next argument is the delay after how

the next argument is the delay after how many milliseconds will we execute this

many milliseconds will we execute this task I said 3 seconds let's say 3,000

task I said 3 seconds let's say 3,000 milliseconds then after a delay of 3

milliseconds then after a delay of 3 seconds 3,000 milliseconds do your task

seconds 3,000 milliseconds do your task that we're passing in so after 3 seconds

that we're passing in so after 3 seconds will

output hello or if this were 1,000 millisecs it

hello or if this were 1,000 millisecs it would only take a

would only take a second hello you can also schedule at a

second hello you can also schedule at a fixed rate our timer can do things

fixed rate our timer can do things periodically so let's repeat our task of

periodically so let's repeat our task of saying hello more than just once so we

saying hello more than just once so we have our delay you know what I'll set

have our delay you know what I'll set that to be zero the next argument is for

that to be zero the next argument is for the period what is the delay in

the period what is the delay in milliseconds between repetitions let's

milliseconds between repetitions let's say 1,000 milliseconds so 1

say 1,000 milliseconds so 1 second starting immediately 0

second starting immediately 0 milliseconds print hello every 1,000

milliseconds print hello every 1,000 milliseconds every second let's try

milliseconds every second let's try it hello hello hello hello I think you

it hello hello hello hello I think you get the idea or you could add a delay

get the idea or you could add a delay that's the second argument let's say

that's the second argument let's say after a delay delay of 3,000

after a delay delay of 3,000 milliseconds 3 seconds repeat this line

milliseconds 3 seconds repeat this line of code every 1,000 milliseconds 1

of code every 1,000 milliseconds 1 second so now there's going to be a

second so now there's going to be a delay of 3

delay of 3 seconds then we output hello every 1

seconds then we output hello every 1 second now how do you cancel this timer

second now how do you cancel this timer once it's started well you can use the

once it's started well you can use the cancel

cancel method where should we add that exactly

method where should we add that exactly well we can add that within our task

well we can add that within our task we'll need some sort of stopping

we'll need some sort of stopping condition kind of like a wild Loop so

condition kind of like a wild Loop so let's say this I would like to say hello

let's say this I would like to say hello three times I'll create a local variable

three times I'll create a local variable of count I'll set that to be

of count I'll set that to be three intellig wants me to make this

three intellig wants me to make this final you don't have to I'll keep it as

final you don't have to I'll keep it as is so again we are within our Anonymous

is so again we are within our Anonymous class we're declaring a variable to use

class we're declaring a variable to use within the context of our

within the context of our task within the run method we'll output

task within the run method we'll output hello decrement our count by one count

hello decrement our count by one count minus

minus minus then using an if statement this is

minus then using an if statement this is how we're going to escape if our count

how we're going to escape if our count is less than

is less than zero then let's

zero then let's say task

say task complete and then to cancel the timer we

complete and then to cancel the timer we will take our timer object called the

will take our timer object called the cancel

method all right let's try it I'll set the delay to be zero so it starts

the delay to be zero so it starts immediately every 1,000 milliseconds

immediately every 1,000 milliseconds print hello whoops it looks like that's

print hello whoops it looks like that's less than or equal to zero I fixed it

less than or equal to zero I fixed it all right so starting immediately the

all right so starting immediately the delay is zero every 1,000 milliseconds

delay is zero every 1,000 milliseconds print hello but only do it three times

print hello but only do it three times and then we cancel the timer to stop

and then we cancel the timer to stop because we don't want to say hello

because we don't want to say hello forever and here it

forever and here it is 1 2 3 task

is 1 2 3 task complete all right everybody so that is

complete all right everybody so that is timer and timer task timer is a class

timer and timer task timer is a class that schedules tasks at specific times

that schedules tasks at specific times or periodically it's useful for sending

or periodically it's useful for sending notifications scheduled updates or other

notifications scheduled updates or other repetitive actions timer task is the

repetitive actions timer task is the task you're going to perform when the

task you're going to perform when the timer says so in the next video we're

timer says so in the next video we're going to use timer and timer task to

going to use timer and timer task to create a countdown timer all right

create a countdown timer all right everybody so that is both timer and

everybody so that is both timer and timer task in

timer task in Java why hello there everybody in this

Java why hello there everybody in this video we're going to create a countdown

video we're going to create a countdown timer program using Java this is meant

timer program using Java this is meant to serve as more of a mini project to

to serve as more of a mini project to get us used to working with timer tasks

get us used to working with timer tasks let's begin we'll accept user input but

let's begin we'll accept user input but we're going to set that up near the end

we're going to set that up near the end it's going to be easier for us to

it's going to be easier for us to understand this program at first if we

understand this program at first if we set the countdown timer to be a raw

set the countdown timer to be a raw number like 10 to work with timer tasks

number like 10 to work with timer tasks we'll need a timer to keep track of the

we'll need a timer to keep track of the time timer timer equals new

time timer timer equals new timer we'll be importing our classes as

timer we'll be importing our classes as we go along long be sure to do that

we go along long be sure to do that import them from the Java utility

import them from the Java utility package then we'll need a timer task

package then we'll need a timer task timer task I'll name this task for short

timer task I'll name this task for short equals new timer task be sure to import

equals new timer task be sure to import this

this class now there's one issue though with

class now there's one issue though with our timer task object we have to

our timer task object we have to override the run method one option

override the run method one option although it's not the best is to create

although it's not the best is to create a new class and then inherit from the

a new class and then inherit from the timer task class so this would be the

timer task class so this would be the parent class and then we can override

parent class and then we can override the run method but since we don't plan

the run method but since we don't plan on reusing that class what we could do

on reusing that class what we could do instead is use an anonymous class after

instead is use an anonymous class after the set of parentheses add a set of

the set of parentheses add a set of curly braces then add that semicolon to

curly braces then add that semicolon to the end for a onetime use we can

the end for a onetime use we can override the run method of our timer

override the run method of our timer task object because we only plan on

task object because we only plan on using it once so we can write an

using it once so we can write an anonymous class rather than create a

anonymous class rather than create a whole new class that we're only going to

whole new class that we're only going to use once so we will

use once so we will override the run method

override the run method public void

public void run when our timer executes our task

run when our timer executes our task what would we like to do well we're

what would we like to do well we're going to Output a number the number for

going to Output a number the number for our countdown timer so within our

our countdown timer so within our Anonymous class let's create an integer

Anonymous class let's create an integer variable of count for the time being

variable of count for the time being let's set this to a low number like five

let's set this to a low number like five intelligent wants us to make this

intelligent wants us to make this variable final but we'll be accepting

variable final but we'll be accepting user input momentarily so you don't need

user input momentarily so you don't need to do that my IDE of intelligent is

to do that my IDE of intelligent is recommending that you can just ignore

recommending that you can just ignore that so let's say that our count is

that so let's say that our count is going to start at five and we'll

going to start at five and we'll decrement by one then display happy New

decrement by one then display happy New Year when count to zero so why don't we

Year when count to zero so why don't we do the following within our run method

do the following within our run method we'll output our count variable at first

we'll output our count variable at first it's going to be

it's going to be five then we'll decrement count by one

five then we'll decrement count by one count minus

count minus minus we'll need to escape the run

minus we'll need to escape the run method well we can do that with an if

method well we can do that with an if statement

statement we will check if our count is less than

we will check if our count is less than zero if it is let's output happy New

Year and then to stop our timer we'll take our timer object called the cancel

take our timer object called the cancel method now we have to set up our timer

method now we have to set up our timer we will do that outside the timer task

we will do that outside the timer task Anonymous

Anonymous class so right here is good we will take

class so right here is good we will take our timer called the schedule

our timer called the schedule method schedule will take a task our

method schedule will take a task our timer

timer task and execute it after a delay let's

task and execute it after a delay let's set the delay to be zero now this is

set the delay to be zero now this is only going to run once there's a better

only going to run once there's a better method for this let me just

method for this let me just demonstrate so we get the number five

demonstrate so we get the number five and our program

and our program stops so what we're going to use instead

stops so what we're going to use instead is schedule at fixed rate

is schedule at fixed rate the schedule at fixed rate method but

the schedule at fixed rate method but there's three arguments we have to pass

there's three arguments we have to pass in first is the task the delay and then

in first is the task the delay and then the

the period we have our task the delay is

period we have our task the delay is zero what is the period in between

zero what is the period in between executions let's set that to be 1,000

executions let's set that to be 1,000 milliseconds every 1 second 1,000

milliseconds every 1 second 1,000 milliseconds perform your task and our

milliseconds perform your task and our task is to display our countdown

task is to display our countdown whatever the count currently is

whatever the count currently is all right let's test this again we're

all right let's test this again we're setting our count to be five initially

setting our count to be five initially but we'll be accepting user input

but we'll be accepting user input momentarily we start at 5 and we're

momentarily we start at 5 and we're going to count down to zero then display

going to count down to zero then display happy New

happy New Year all right after zero we display

Year all right after zero we display happy New Year and our program exits

happy New Year and our program exits because we canceled the

because we canceled the timer now if we don't cancel the timer

timer now if we don't cancel the timer I'm just going to cut this momentarily

I'm just going to cut this momentarily it's going to continue forever

we keep on displaying happy New Year and we're going into negative

we're going into negative seconds so that's why we need to cancel

seconds so that's why we need to cancel the timer so that it stops all right now

the timer so that it stops all right now we'll accept user input because we want

we'll accept user input because we want a user to type in the number to

a user to type in the number to countdown from rather than us

countdown from rather than us programmers just typing in a random

programmers just typing in a random number so we will need a

scanner scanner scanner equals new scanner then pass in

scanner then pass in system.in import this class and then

system.in import this class and then we'll need a

we'll need a prompt let's output the

prompt let's output the following enter number of seconds to

following enter number of seconds to countdown

countdown from I'll use print rather than print

from I'll use print rather than print line let's create an integer variable of

line let's create an integer variable of response set that equal to use our

response set that equal to use our scanner call the next int method to get

scanner call the next int method to get the next integer from the user then we

the next integer from the user then we will set our count variable equal to the

will set our count variable equal to the response whatever the user types in so

response whatever the user types in so now the user can type in a number and we

now the user can type in a number and we can count down from that number rather

can count down from that number rather than just placing a random number here

than just placing a random number here all right let's test

all right let's test this enter number of seconds to count

this enter number of seconds to count down from let's say 10 we're going to

down from let's say 10 we're going to count down from 10 so we start at 10 and

count down from 10 so we start at 10 and we're going to count down to

zero zero happy New Year and then the program exits so you can type in any

program exits so you can type in any number you could even set this to a

number you could even set this to a higher number like

higher number like 60 but I'm not going to make you wait

60 but I'm not going to make you wait that

that long all right everybody that is a

long all right everybody that is a countdown timer program that you can

countdown timer program that you can write as a mini project using Java hello

write as a mini project using Java hello there every everybody in this video I

there every everybody in this video I got to cover generics in Java generics

got to cover generics in Java generics it's a concept it's where you can write

it's a concept it's where you can write a class interface or method and it's

a class interface or method and it's compatible with different data types

compatible with different data types there's two things we need a type

there's two things we need a type parameter and a type argument so with

parameter and a type argument so with type parameters it's a set of angle

type parameters it's a set of angle brackets with a letter inside for

brackets with a letter inside for example T basically this acts as a

example T basically this acts as a placeholder and it gets replaced with

placeholder and it gets replaced with the real type now on the other hand type

the real type now on the other hand type arguments with various objects and data

arguments with various objects and data structures you'll see a pair of angle

structures you'll see a pair of angle brackets with a type inside such as a

brackets with a type inside such as a string but it really can be anything it

string but it really can be anything it can be an integer or a

can be an integer or a Boolean really anything type arguments

Boolean really anything type arguments specify the type we send arguments to

specify the type we send arguments to parameters really our type parameter is

parameters really our type parameter is just acting as a placeholder anything

just acting as a placeholder anything that uses this type parameter it doesn't

that uses this type parameter it doesn't know the data type that it's going to

know the data type that it's going to receive it's set up to receive really

receive it's set up to receive really anything or a primitive using a rapper

anything or a primitive using a rapper class let me give you an example of

class let me give you an example of where you already see a gener being used

where you already see a gener being used for example array lists to create an

for example array lists to create an array list we add a set of angle

array list we add a set of angle brackets after array list and we have to

brackets after array list and we have to specify the type what is this array list

specify the type what is this array list going to store for example strings we

going to store for example strings we would write the data type of string

would write the data type of string let's say that this array list is named

let's say that this array list is named fruits fruits equals new array list and

fruits fruits equals new array list and then we need a set of angle brackets

then we need a set of angle brackets again parenthesis semicolon in modern

again parenthesis semicolon in modern Java within the second set of angle

Java within the second set of angle brackets you don't necessarily need to

brackets you don't necessarily need to type the data type again Java can infer

type the data type again Java can infer that so you can leave it empty this is

that so you can leave it empty this is the diamond

the diamond operator we have an array list that can

operator we have an array list that can store strings we have specified the type

store strings we have specified the type argument and now we can store some

argument and now we can store some strings within our array list so let's

strings within our array list so let's take our array list of fruits call the

take our array list of fruits call the ad method and add a few names of fruits

ad method and add a few names of fruits such as an

such as an apple let's do two

apple let's do two more Apple orange banana

more Apple orange banana currently the way that we set up this

currently the way that we set up this array list it's compatible with strings

array list it's compatible with strings because that's what we set the type

because that's what we set the type argument to be now if I set this to be

argument to be now if I set this to be integers well we can't store strings

integers well we can't store strings anymore but we could store numbers 1 2 3

anymore but we could store numbers 1 2 3 that's

that's fine let me change that back generally

fine let me change that back generally speaking an array data structure can

speaking an array data structure can store all sorts of different data types

store all sorts of different data types but when we create one we have to

but when we create one we have to specify what we're storing that's the

specify what we're storing that's the type argument it's because within the

type argument it's because within the array list class we have a type

array list class we have a type parameter set up a set of angle brackets

parameter set up a set of angle brackets with a letter inside in many cases

with a letter inside in many cases you'll see t meaning type for type

you'll see t meaning type for type parameter so let's actually take a look

parameter so let's actually take a look at our array list I am going to locate

at our array list I am going to locate array list jump to Source here's the

array list jump to Source here's the class for our array list there's a lot

class for our array list there's a lot of advanced Java in here don't worry

of advanced Java in here don't worry about that but what I want you to pay

about that but what I want you to pay attention to is the type parameter that

attention to is the type parameter that comes after after the array list class

comes after after the array list class name we have angle brackets and a letter

name we have angle brackets and a letter inside in this case e meaning element

inside in this case e meaning element because an array list has elements of

because an array list has elements of data by using this type parameter our

data by using this type parameter our array list is set up to store elements

array list is set up to store elements of various types we just have to specify

of various types we just have to specify what the type is going to be when we

what the type is going to be when we actually do store data and in my example

actually do store data and in my example we're using strings but like I said

we're using strings but like I said before we can change the data type of

before we can change the data type of what we're storing we just have to

what we're storing we just have to change the type argument I'll store

change the type argument I'll store booleans true

false true I don't know what that has to do

true I don't know what that has to do with fruits but I'm just trying to prove

with fruits but I'm just trying to prove a point

a point here so now what we're going to do is

here so now what we're going to do is actually use type parameters so let's

actually use type parameters so let's delete our array list using generics you

delete our array list using generics you can write some logic within a class

can write some logic within a class interface or method and it's compatible

interface or method and it's compatible with many different data types so what

with many different data types so what we're going to do in this example is

we're going to do in this example is create a class of box

create a class of box class

class box we'll be using a type parameter to

box we'll be using a type parameter to store all sorts of different things

store all sorts of different things within our box we can store a string

within our box we can store a string within our box an integer a double A

within our box an integer a double A Boolean even more complex objects so we

Boolean even more complex objects so we will set up a type parameter with a set

will set up a type parameter with a set of angle brackets then type t t is a

of angle brackets then type t t is a common convention meaning type let's say

common convention meaning type let's say that when we create a box object our box

that when we create a box object our box is going to act as a container we'll

is going to act as a container we'll store a value inside

store a value inside our box is going to be a reusable class

our box is going to be a reusable class we won't always know what the data type

we won't always know what the data type of what we're storing is going to be so

of what we're storing is going to be so what we could do is set the data type to

what we could do is set the data type to be T let's say that this variable is an

be T let's say that this variable is an item we're storing an item within a box

item we're storing an item within a box with t it does mean type but I like to

with t it does mean type but I like to think of it as thing we're storing a

think of it as thing we're storing a thing an item within our box we don't

thing an item within our box we don't know what this thing is going to be but

know what this thing is going to be but really it means type and that's not as

really it means type and that's not as fun T item we don't know what the data

fun T item we don't know what the data type is if it's always going to be a

type is if it's always going to be a string we could just set this to be a

string we could just set this to be a string but what if somebody is storing

string but what if somebody is storing an integer an INT or we can use the

an integer an INT or we can use the rapper class of integer we don't know

rapper class of integer we don't know what the type is going to be let's

what the type is going to be let's create a method where we will set our

create a method where we will set our item let's say that this is public void

item let's say that this is public void it's not going to return anything set

it's not going to return anything set item we'll have one parameter what's the

item we'll have one parameter what's the data type of what we're receiving well

data type of what we're receiving well we don't know so we're going to use our

we don't know so we're going to use our type parameter of

type parameter of t t is the data type it's generic we

t t is the data type it's generic we will receive an

will receive an item let's take this. item and set it to

item let's take this. item and set it to be the item that we

be the item that we receive we'll create a method to get our

receive we'll create a method to get our item public now we're going to be

item public now we're going to be returning an item the data type is T so

returning an item the data type is T so the return type is also going to be T

the return type is also going to be T we're returning a value of the T data

we're returning a value of the T data type we will create a method to get

item we will return this. item we can put things in our box and we can get

put things in our box and we can get things from our

things from our box all right this class is done our box

box all right this class is done our box class is set up to be reusable we can

class is set up to be reusable we can store all sorts of different things so

store all sorts of different things so to say within our box we will attempt to

to say within our box we will attempt to create a box object for now let's say

create a box object for now let's say box box equals new box but there's one

box box equals new box but there's one step that we're

step that we're missing we have a warning here raw use

missing we have a warning here raw use of parameterized class

of parameterized class box we need to set up a type argument

box we need to set up a type argument what are we going to be putting in our

what are we going to be putting in our box what's its data type our box class

box what's its data type our box class wants to know so we will use a type

wants to know so we will use a type argument after the class of box add a

argument after the class of box add a set of angle brackets then type what

set of angle brackets then type what we're going to store so let's say we're

we're going to store so let's say we're going to store strings within our box

going to store strings within our box values of the string data type and then

values of the string data type and then we do need the diamond operator after

we do need the diamond operator after the second box and we're good we now

the second box and we're good we now have a box object but it's set up to

have a box object but it's set up to store strings let's add some items to

store strings let's add some items to our box we've even created a few methods

our box we've even created a few methods for this set item let's take our box

for this set item let's take our box call set item but we have to pass in a

call set item but we have to pass in a string let's add a banana to our

string let's add a banana to our box and then we will get the banana from

box and then we will get the banana from the box using the get item method and

the box using the get item method and now I want to get the banana box. get

item here we go we have our banana we have successfully retrieved the banana

have successfully retrieved the banana from the

from the box our box class is compatible with all

box our box class is compatible with all sorts of different data types this time

sorts of different data types this time let's store an integer we will use the

let's store an integer we will use the wrapper class of integer but we can no

wrapper class of integer but we can no longer add a banana to the Box because

longer add a banana to the Box because it's a string I'll attempt to do so

it's a string I'll attempt to do so string cannot be converted to

string cannot be converted to integer unfortunately bananas are not

integer unfortunately bananas are not numbers but I can add the number three

numbers but I can add the number three to our

to our box we have the number three within our

box we have the number three within our box if I attempt to add a double like

box if I attempt to add a double like 3.14 we get a warning

incompatible types double cannot be converted to

converted to integer so I would have to set the type

integer so I would have to set the type argument to be double to add doubles to

argument to be double to add doubles to our

our box

box 3.14 basically with our box class we're

3.14 basically with our box class we're writing the logic of how a box works you

writing the logic of how a box works you put something in and you can take

put something in and you can take something out and it's compatible with

something out and it's compatible with different data

different data types we just have to use a type

types we just have to use a type argument when creating a box object we

argument when creating a box object we have to let Java know what we're storing

have to let Java know what we're storing within it exactly all right let me give

within it exactly all right let me give you another example now with type

you another example now with type parameters you can have more than one

parameters you can have more than one type we can have two or more different

type we can have two or more different types usually the common convention is

types usually the common convention is to use U after

to use U after T so we're going to create a new class

T so we're going to create a new class file new Java class we will create a

file new Java class we will create a class of

class of product here we're going to write the

product here we're going to write the logic of how a product works with a

logic of how a product works with a product you have an item and you have a

product you have an item and you have a price we will set up a type parameter

price we will set up a type parameter let me zoom in we'll have one type of t

let me zoom in we'll have one type of t and a common convention for the second

and a common convention for the second type is U because in the English

type is U because in the English alphabet the letter U comes after T if

alphabet the letter U comes after T if you had a third argument that would be V

you had a third argument that would be V by Common

by Common convention so we'll just stick with t

convention so we'll just stick with t and

and u we will have a generic type of

u we will have a generic type of item and another generic type of price

item and another generic type of price we don't know if our item is going to be

we don't know if our item is going to be a string or a more complex object our

a string or a more complex object our price could be an integer a floating

price could be an integer a floating Point number a double we don't know but

Point number a double we don't know but that's why we're setting it up this

that's why we're setting it up this way now we'll need a Constructor we will

way now we'll need a Constructor we will take our

take our product then set up some parameters the

product then set up some parameters the data type of our item is t t item but if

data type of our item is t t item but if we're creating a product we also need a

we're creating a product we also need a price the data type of our price is u

price the data type of our price is u U price this. item equals the item that

U price this. item equals the item that we

we receive this. price equals the price

receive this. price equals the price that we

that we receive okay let's do a test run let's

receive okay let's do a test run let's go to our main Java

go to our main Java file product product equals new

file product product equals new product and again we need those type

product and again we need those type arguments so this time we actually need

arguments so this time we actually need two because our class is set up to

two because our class is set up to receive two type arguments T and

receive two type arguments T and U for our product let's say that the

U for our product let's say that the first type is going to be a string

first type is going to be a string followed by a double and then we need

followed by a double and then we need the diamond operator after the second

the diamond operator after the second product all right now we have to pass in

product all right now we have to pass in arguments to the class because we have a

arguments to the class because we have a Constructor we have to pass in an item

Constructor we have to pass in an item and its

and its price and with our type arguments we set

price and with our type arguments we set that up to be a string and a double we

that up to be a string and a double we have to pass in those types for our

have to pass in those types for our product let's say that it's an apple and

product let's say that it's an apple and an apple is 50 Cents that's a

an apple is 50 Cents that's a double let's create two methods within

double let's create two methods within our product class we will create a

our product class we will create a method to get our item let's say public

method to get our item let's say public we're returning an item the data type is

we're returning an item the data type is T so we're going to return

T so we're going to return T get

T get item we will return this do

item we will return this do item then to return the

item then to return the price let's say public U cuz we're

price let's say public U cuz we're returning the price it has a type of

returning the price it has a type of U Get

U Get price return this do

price we have our product object I'm going to Output take our

object I'm going to Output take our product object called the get item

product object called the get item method and this is going to return are

method and this is going to return are apple or I could get the price get

apple or I could get the price get price and that is

price and that is 0.5 you can use string format but that

0.5 you can use string format but that might be overkill for this lesson all

might be overkill for this lesson all right let's create a second product so

right let's create a second product so we'll have product

we'll have product one and product

one and product two Now product two will use an integer

two Now product two will use an integer instead of a

instead of a double and let's say that these are

double and let's say that these are tickets like movie tickets ticket and

tickets like movie tickets ticket and the price will be $15 for

the price will be $15 for $15 let's take product

$15 let's take product two call the get item

ticket and we should have a price get price the price of a movie ticket is$ 15

price the price of a movie ticket is$ 15 $15 all right everybody so that is an

$15 all right everybody so that is an introduction to two generics it's a

introduction to two generics it's a concept where you can write a class

concept where you can write a class interface or method that is compatible

interface or method that is compatible with different data types basically

with different data types basically we're writing the logic of how this

we're writing the logic of how this class works and it's compatible with all

class works and it's compatible with all different types you just have to set up

different types you just have to set up a type parameter and then pass in type

a type parameter and then pass in type arguments and well everybody that is an

arguments and well everybody that is an introduction to generics in Java well

introduction to generics in Java well it's up everybody so today I got to

it's up everybody so today I got to explain hashmaps in Java hashmaps are a

explain hashmaps in Java hashmaps are a popular data structure

popular data structure they store a pair of values a key value

they store a pair of values a key value pair you have a key and a value

pair you have a key and a value associated with that key the keys have

associated with that key the keys have to be unique but the values can be

to be unique but the values can be duplicated hashmaps do not maintain any

duplicated hashmaps do not maintain any order but they are very memory efficient

order but they are very memory efficient when creating a hashmap we have to set

when creating a hashmap we have to set up type parameters we have to specify

up type parameters we have to specify what the data type of the key is and its

what the data type of the key is and its value here's how to create a hashmap we

value here's how to create a hashmap we will type hashmap let's say map for

will type hashmap let's say map for short

short hashmap map equals new hash

hashmap map equals new hash map we'll need to import this class it

map we'll need to import this class it looks like we're missing something let's

looks like we're missing something let's take a look raw use of parameterized

take a look raw use of parameterized class

class hashmap if we take a look at the hashmap

hashmap if we take a look at the hashmap class we have type parameter set up

class we have type parameter set up there's two values we learned about type

there's two values we learned about type parameters in the last video on generics

parameters in the last video on generics we can store any two types of values

we can store any two types of values within a hashmap we have a key and a

within a hashmap we have a key and a value represented by K and V we have to

value represented by K and V we have to send type arguments to the type

send type arguments to the type parameters when creating a hashmap we'll

parameters when creating a hashmap we'll have to set up some type arguments so

have to set up some type arguments so after our hashmap we have to list the

after our hashmap we have to list the data type of what we're storing these

data type of what we're storing these have to be reference data types so let's

have to be reference data types so let's say with our map we're going to have

say with our map we're going to have products an item and a price so for the

products an item and a price so for the item that could be a string a string

item that could be a string a string representation of our

representation of our item so for the price we could do an

item so for the price we could do an integer but I think a double would be

integer but I think a double would be better because you can have dollars and

better because you can have dollars and cents then we also need to use the

cents then we also need to use the diamond operator after the second

diamond operator after the second hashmap you don't need to State the data

hashmap you don't need to State the data types again even though you technically

types again even though you technically could Java can actually infer what the

could Java can actually infer what the data type is so after the second hashmap

data type is so after the second hashmap add the diamond operator and there we go

add the diamond operator and there we go we have our hashmap that we have named

we have our hashmap that we have named map the way that we've set this up is

map the way that we've set this up is that we've told the hashmap class we're

that we've told the hashmap class we're going to store a string as the key and a

going to store a string as the key and a double as the value so to put things in

double as the value so to put things in a hash map we're going to take our map

a hash map we're going to take our map called the put method we're going to put

called the put method we're going to put something in the hashmap we've specified

something in the hashmap we've specified that we're storing a string then a

that we're storing a string then a double a string for the key and a double

double a string for the key and a double for the value so let's say we have a

for the value so let's say we have a store and in our store we sell produce

store and in our store we sell produce we will have an apple and its price will

we will have an apple and its price will be 50 CS

be 50 CS 0.50 to put some something in a hashmap

0.50 to put some something in a hashmap you use the put method we have to pass

you use the put method we have to pass in two values as arguments all right

in two values as arguments all right let's add a few more

let's add a few more things we'll have an

things we'll have an orange an orange will be 75 cents let's

orange an orange will be 75 cents let's say then a banana bananas are pretty

say then a banana bananas are pretty cheap they will be 25 cents all right

cheap they will be 25 cents all right let's take a look at our hash map I'm

let's take a look at our hash map I'm going to show you what happens if we

going to show you what happens if we output our map directly system.out.print

output our map directly system.out.print line our map our hash

line our map our hash map and here's what we have we have all

map and here's what we have we have all the key value pairs printed within our

the key value pairs printed within our hash map we have a string and a double

hash map we have a string and a double string double string

string double string double now with hash Maps the keys have

double now with hash Maps the keys have to be unique for example let's say I try

to be unique for example let's say I try and put another orange within here we'll

and put another orange within here we'll attempt to add another orange and we'll

attempt to add another orange and we'll see what happens

see what happens exactly put another Orange

exactly put another Orange within our map and let's say that the

within our map and let's say that the price is 1

price is 1 million Venezuelan dollars yes oranges

million Venezuelan dollars yes oranges are very expensive in Venezuela because

are very expensive in Venezuela because of inflation so here's what happens if

of inflation so here's what happens if we have duplicate

we have duplicate Keys you actually overwrite the previous

Keys you actually overwrite the previous key value pair our orange is now worth 1

key value pair our orange is now worth 1 million Venezuelan dollars so do keep

million Venezuelan dollars so do keep that in mind hashmaps cannot have

that in mind hashmaps cannot have duplicate keys if you put another key

duplicate keys if you put another key value pair with than a hashmap and it

value pair with than a hashmap and it already exists you'll overwrite it but

already exists you'll overwrite it but that's also good if you want to change

that's also good if you want to change one of the key value pairs let's add one

one of the key value pairs let's add one more key value pair let's say a coconut

more key value pair let's say a coconut map. put we will put a coconut within

map. put we will put a coconut within our hash map coconuts are a little more

our hash map coconuts are a little more expensive they'll be

expensive they'll be $1 let's print our map to test

$1 let's print our map to test it there's our

it there's our coconut then we can remove an element to

coconut then we can remove an element to remove an element take your map call the

remove an element take your map call the remove

remove method here you're going to pass in a

method here you're going to pass in a key let's remove our

key let's remove our Apple then print our

Apple then print our map there the apple is gone we have

map there the apple is gone we have orange banana coconut but no apple so

orange banana coconut but no apple so I'm going to keep that in but turn it

I'm going to keep that in but turn it into a

into a comment to get the value associated with

comment to get the value associated with the key you can use the get method so

the key you can use the get method so let me delete this print line statement

let me delete this print line statement we will take our map called the get

we will take our map called the get method let's get the value with this

method let's get the value with this key give me the value where the key is

key give me the value where the key is Apple is what we're

Apple is what we're saying that would be

saying that would be 0.5 meaning

0.5 meaning 50 or we can get our

coconut the value associated with this key is one meaning

key is one meaning $1 all right you can also check to see

$1 all right you can also check to see if a key or a value exists here's

if a key or a value exists here's how we'll use the contains key method

how we'll use the contains key method take our map call the contains key

take our map call the contains key method and then pass in a key is there a

method and then pass in a key is there a key of

key of banana that returns a Boolean in this

banana that returns a Boolean in this case

case true is there a pineapple there is not

true is there a pineapple there is not so that returns

so that returns false you could use this with than an if

false you could use this with than an if statement here's

statement here's how we will check

how we will check if let me zoom in if our map call the

if let me zoom in if our map call the contains key

contains key method and then pass in a key does our

method and then pass in a key does our map contain any

map contain any apples contains key

apples contains key Apple if that returns true we'll

Apple if that returns true we'll output

output map. getet then we'll get our Apple

map. getet then we'll get our Apple this will give us the price else if

this will give us the price else if contains key is false then we'll output

contains key is false then we'll output something else we'll

output key not found all right let's test this so we do

found all right let's test this so we do have an apple we've set this up to

have an apple we've set this up to return the

return the price but let's say we are looking for a

price but let's say we are looking for a pineapple contains key

pineapple contains key pineapple if we do find a pineapple we

pineapple if we do find a pineapple we will get the price price currently

will get the price price currently there's no pineapples within our map key

there's no pineapples within our map key not found so that's how the contains key

not found so that's how the contains key method would be

method would be useful we also have the capability to

useful we also have the capability to check to see if a map contains a value

check to see if a map contains a value so we will take our map within a print

so we will take our map within a print line statement called the

line statement called the contains Value method and then pass in a

contains Value method and then pass in a value is there anything that's $1

value is there anything that's $1 1.0 this returns a Boolean and that's

1.0 this returns a Boolean and that's true our key of coconut has a value of

true our key of coconut has a value of 1.0 $1 and you do have to pay attention

1.0 $1 and you do have to pay attention to the data type too if I were to pass

to the data type too if I were to pass in an

in an integer this does return false you do

integer this does return false you do have to keep that in mind too that's how

have to keep that in mind too that's how to check to see if a map contains a key

to check to see if a map contains a key and a

value you can return the size of a map using map. size map dot called the size

using map. size map dot called the size method currently there's four key value

method currently there's four key value pairs within our map

pairs within our map this will return the number four to get

this will return the number four to get the size of a map call the size

the size of a map call the size method all right now the last thing that

method all right now the last thing that we're going to do if we were to print

we're going to do if we were to print our

our map we're given this ugly

map we're given this ugly formatting where we have a set of curly

formatting where we have a set of curly braces then all the key value pairs

braces then all the key value pairs comma

comma separated this time using a for loop

separated this time using a for loop we're going to cycle through all the key

we're going to cycle through all the key value pairs we will create an enhanced

value pairs we will create an enhanced for Loop

for Loop what we're going to iterate through is

what we're going to iterate through is every key and these have a string data

every key and these have a string data type because that's the way that we set

type because that's the way that we set them

them up the data type of each element is

up the data type of each element is going to be a string which we will name

going to be a string which we will name key colon think of it as in for every

key colon think of it as in for every key in now what we have to do is get all

key in now what we have to do is get all the keys from our map and there's

the keys from our map and there's actually a method for that a beginners

actually a method for that a beginners friendly way to get all the keys from

friendly way to get all the keys from our map what we can do is take our map

our map what we can do is take our map call the key set

call the key set method this will return all the keys

method this will return all the keys within our map and they're iterable so

within our map and they're iterable so we can use them within a for Loop for

we can use them within a for Loop for every key in our set of keys what do we

every key in our set of keys what do we want to do let's do the following within

want to do let's do the following within a print line statement let's print our

a print line statement let's print our key plus we'll list each product and its

key plus we'll list each product and its price key

price key plus maybe I'll add a colon space then

plus maybe I'll add a colon space then pick a unit of currency I'll pick

pick a unit of currency I'll pick American dollars for every key we need

American dollars for every key we need to get its value so we can use the get

to get its value so we can use the get method plus map. getet pass in our key

method plus map. getet pass in our key by using an enhanced for Loop we can

by using an enhanced for Loop we can customize the output of the key value

customize the output of the key value Pairs and I think this looks a lot

Pairs and I think this looks a lot better we have each product each piece

better we have each product each piece of fruit and its price laid out in this

of fruit and its price laid out in this format you could technically use print F

format you could technically use print F if you want to display two digits after

if you want to display two digits after the decimal

the decimal but that might be a little too much for

but that might be a little too much for this lesson I want to keep it as simple

this lesson I want to keep it as simple as possible all right everybody so those

as possible all right everybody so those are hashmaps it's a data structure that

are hashmaps it's a data structure that stores key value pairs the keys have to

stores key value pairs the keys have to be unique but the values can be

be unique but the values can be duplicated we have to specify the type

duplicated we have to specify the type for the key and its value and well

for the key and its value and well everybody those are hashmaps in

everybody those are hashmaps in Java all right let's do this thing

Java all right let's do this thing everybody today we're talking about

everybody today we're talking about enums en nums is short for enumerations

enums en nums is short for enumerations they're a special kind of class they

they're a special kind of class they represent a fixed set of constants by

represent a fixed set of constants by using enums they improve code

using enums they improve code readability and are easy to maintain one

readability and are easy to maintain one of the major benefits of enums is that

of the major benefits of enums is that they're more efficient with switches

they're more efficient with switches when comparing strings so basically an

when comparing strings so basically an enum is a special kind of class where we

enum is a special kind of class where we declare constants here's a demonstration

declare constants here's a demonstration we're going to create a new class file

we're going to create a new class file new Java class we're going to select

new Java class we're going to select enum enum is a special kind of class

enum enum is a special kind of class sort of like like how an interface is a

sort of like like how an interface is a special kind of

special kind of class we will create an enum of

class we will create an enum of day public enum Day within this Java

day public enum Day within this Java class we can declare some constants what

class we can declare some constants what we're going to write is enum constants a

we're going to write is enum constants a common convention for these constants is

common convention for these constants is that all the letters are uppercase so

that all the letters are uppercase so after the enum constant We'll add a set

after the enum constant We'll add a set of parentheses then associate this

of parentheses then associate this constant with the value so let's say

constant with the value so let's say that we're working with days of the week

that we're working with days of the week Sunday will be the the first day of the

Sunday will be the the first day of the week Sunday we'll have a value of one

week Sunday we'll have a value of one let's do this with the other days of the

let's do this with the other days of the week Monday parentheses then a value

week Monday parentheses then a value Monday will be the second day of the

Monday will be the second day of the week then we'll just follow this

pattern and all these constants with a semicolon all right we have our enum

semicolon all right we have our enum constants they have values 1 through 7

constants they have values 1 through 7 we're receiving some warnings here

we're receiving some warnings here expected zero arguments but one found

expected zero arguments but one found what we need to do is create a

what we need to do is create a Constructor a Constructor for our day

Constructor a Constructor for our day class when we Define these enum

class when we Define these enum constants we're automatically going to

constants we're automatically going to call the Constructor for this enum class

call the Constructor for this enum class and then pass in this value let's create

and then pass in this value let's create a field of day number for days of the

a field of day number for days of the week we'll make these values private

week we'll make these values private we'll use the private access modifier we

we'll use the private access modifier we don't want the ability to change them

don't want the ability to change them we'll make them final these are integers

we'll make them final these are integers that's the data type we'll name these

that's the data type we'll name these values day

values day number when we Define these enum

number when we Define these enum constants we're automatically going to

constants we're automatically going to call the Constructor and then pass in

call the Constructor and then pass in this value to the

this value to the Constructor for the parameters we'll

Constructor for the parameters we'll have int then our field of day

have int then our field of day number this day

number this day number equals the day day number that we

number equals the day day number that we receive if you would like you can add a

receive if you would like you can add a getter method to actually get the day

getter method to actually get the day number we'll use the public access

number we'll use the public access modifier we're returning an integer

modifier we're returning an integer we'll Define a method of get day

we'll Define a method of get day number and we will return our field of

number and we will return our field of this. day number all right and we have

this. day number all right and we have set up our enum class reading and

set up our enum class reading and understanding these enum constants is a

understanding these enum constants is a lot easier than these numbers if I was

lot easier than these numbers if I was looking at the number five I would have

looking at the number five I would have trouble understanding that that means

trouble understanding that that means Thursday now how do we work with these

Thursday now how do we work with these enum constants exactly here's how within

enum constants exactly here's how within our main Java

our main Java file we will create a day object by

file we will create a day object by using this enum

using this enum class let me delete

class let me delete this day day rather than saying new day

this day day rather than saying new day and then passing in a number like one

and then passing in a number like one there's a different approach

there's a different approach we will access the day class Dot and

we will access the day class Dot and then specify a constant a day of the

then specify a constant a day of the week let's say Sunday remember that this

week let's say Sunday remember that this is all caps our day is an object let's

is all caps our day is an object let's output our day and see what it

output our day and see what it outputs this will output Sunday all caps

outputs this will output Sunday all caps if you would rather get the day number

if you would rather get the day number the value that's associated with this

the value that's associated with this enum

enum constant then we can use that getter

constant then we can use that getter method

method day. get day

number so we have Sunday and one where this is really going to be helpful is

this is really going to be helpful is when working with

when working with switches here's a demonstration we will

switches here's a demonstration we will actually use an enhanced

actually use an enhanced switch what are we examining we're

switch what are we examining we're examining our day object if our day

examining our day object if our day matches a case of Monday now this isn't

matches a case of Monday now this isn't a string If This Were A String we would

a string If This Were A String we would enclose this within a set of quotes but

enclose this within a set of quotes but using enums within a switch is actually

using enums within a switch is actually faster than using

faster than using strings if it's Monday then we'll output

strings if it's Monday then we'll output the following we'll use an arrow because

the following we'll use an arrow because this is an enhanced switch then we'll

this is an enhanced switch then we'll output it is a

output it is a weekday then if we have a case of

weekday then if we have a case of Tuesday let me just copy

Tuesday let me just copy this Tuesday we'll also output it is a

this Tuesday we'll also output it is a weekday you can actually combine these

weekday you can actually combine these cases together too you just have to

cases together too you just have to comma separate them

comma separate them so case Monday comma Tuesday do

so case Monday comma Tuesday do this then let's do this with the other

this then let's do this with the other days of the week just for readability

days of the week just for readability I'll put these on new lines each of

I'll put these on new lines each of these

these cases so we have

Wednesday Thursday

Thursday Friday these are all the weekdays Monday

Friday these are all the weekdays Monday through

through Friday then if we have case Saturday

Friday then if we have case Saturday then it's the weekend case Saturday

then it's the weekend case Saturday today we'll do the following output it

today we'll do the following output it is the

is the weekend and we will also add a case for

weekend and we will also add a case for Sunday so currently our day is

Sunday so currently our day is Sunday that will output it is the

Sunday that will output it is the weekend if it were let's say

Wednesday then instead we output it is a weekday if we were comparing strings all

weekday if we were comparing strings all these cases would be enclosed within a

these cases would be enclosed within a set of double quotes kind of like

this but we don't need to do that it's actually more efficient to use

enums for some practice what we'll do this time is accept some user input

this time is accept some user input we'll need a

we'll need a scanner scanner scanner equals new

scanner scanner scanner equals new scanner pass it

scanner pass it system.in import this class be sure to

system.in import this class be sure to close your scanner because I tend to

close your scanner because I tend to forget scanner.

forget scanner. close then we'll need a prompt we will

close then we'll need a prompt we will output the following we'll use print

output the following we'll use print rather than print

rather than print Line enter a day of the

week we will create a string variable let's say response equals use our

let's say response equals use our scanner call the next line

scanner call the next line method all these constants are uppercase

method all these constants are uppercase we'll method chain the two uppercase

we'll method chain the two uppercase method to make our user input

method to make our user input uppercase when creating a day object by

uppercase when creating a day object by using the enum class we will use our

using the enum class we will use our response we will use the value of

response we will use the value of method and then pass in our response now

method and then pass in our response now we should be able to type in a

we should be able to type in a day enter a day of the week I will type

day enter a day of the week I will type Monday it is a weekday let's run this

Monday it is a weekday let's run this again I will type Sunday it is the

again I will type Sunday it is the weekend what if we type in a day that

weekend what if we type in a day that doesn't exist like pizza

doesn't exist like pizza day well we get an exception an illegal

day well we get an exception an illegal argument

argument exception we can catch that exception

exception we can catch that exception using a try and catch block any

using a try and catch block any dangerous code we're going to enclose

dangerous code we're going to enclose within a tri block we will try the

within a tri block we will try the dangerous

code and catch any exceptions we will catch that illegal

argument exception which we will name e if the user input doesn't match one of

if the user input doesn't match one of these e nums then we'll output the

these e nums then we'll output the following please enter a valid

following please enter a valid day let's try it

day let's try it again enter day of the week let's try

again enter day of the week let's try Tuesday it is a

Tuesday it is a weekday

weekday Saturday it is the weekend

Saturday it is the weekend Pizza day please enter a valid day Pizza

Pizza day please enter a valid day Pizza day is not one of our enums but if we

day is not one of our enums but if we wanted to change it so it was we can add

that pizza day will be the eighth day of the

the week at least it should

be we'll need a case for pizza day Pizza day will also be part of the

day Pizza day will also be part of the weekend that just makes sense to

weekend that just makes sense to me all right let's try that

me all right let's try that again enter day of the week Pizza day it

again enter day of the week Pizza day it is the weekend all right all right

is the weekend all right all right everybody so those are enums meaning

everybody so those are enums meaning enumerations they're a special kind of

enumerations they're a special kind of class kind of like how interfaces are a

class kind of like how interfaces are a special kind of class they represent a

special kind of class they represent a fixed set of constants they improve code

fixed set of constants they improve code readability and reliability and where

readability and reliability and where they're really useful is when working

they're really useful is when working with switches

with switches because when working with switches using

because when working with switches using enums is faster than strings if I wasn't

enums is faster than strings if I wasn't using enum constants I could use

using enum constants I could use integers which are also

efficient but as a programmer this is way less readable for me at first clance

way less readable for me at first clance I would have no idea what these numbers

I would have no idea what these numbers are but if they're enum constants this

are but if they're enum constants this is perfectly readable to me these are

is perfectly readable to me these are days of the week that makes sense and

days of the week that makes sense and well everybody those are enums in Java

well everybody those are enums in Java what's going on people in this video I'm

what's going on people in this video I'm going to teach you all about threading

going to teach you all about threading in Java threading allows a program to

in Java threading allows a program to run multiple tasks simultaneously it

run multiple tasks simultaneously it helps to improve performance with

helps to improve performance with timeconsuming

timeconsuming operations such as file input output

operations such as file input output network communications or any other

network communications or any other background tasks any code that is

background tasks any code that is considered timec consuming we can have

considered timec consuming we can have it run on a different thread so that it

it run on a different thread so that it doesn't inconvenience our main program

doesn't inconvenience our main program there's two options to creating a thread

there's two options to creating a thread option one is to extend the thread class

option one is to extend the thread class this is the simpler option but it's

this is the simpler option but it's limited option two is to implement the

limited option two is to implement the runnable interface this option tends to

runnable interface this option tends to be better because by extending the

be better because by extending the thread class we're limited to single

thread class we're limited to single inheritance but by implementing the

inheritance but by implementing the redible interface that's one way around

redible interface that's one way around that in this demonstration I'm going to

that in this demonstration I'm going to show you option two it's actually not

show you option two it's actually not that more difficult than option one and

that more difficult than option one and it gives you more possibilities I'll

it gives you more possibilities I'll give you a demonstration of why

give you a demonstration of why threading is useful in this program

threading is useful in this program where about to write let's say it's a

where about to write let's say it's a game or a quiz or something a user has

game or a quiz or something a user has 10 seconds to respond and if they don't

10 seconds to respond and if they don't times up currently we have one thread

times up currently we have one thread we're running our program on what is

we're running our program on what is known as the main thread without using

known as the main thread without using any other threads besides the main

any other threads besides the main thread I might write my program

thread I might write my program something like this we'll start with the

something like this we'll start with the scanner because we'll be accepting user

scanner because we'll be accepting user input scanner scanner equals new scanner

input scanner scanner equals new scanner pass in

pass in system.in import this class

system.in import this class and close your scanner when you're done

and close your scanner when you're done with it scanner.

close we're going to let a user know that they have let's say 5 Seconds to

that they have let's say 5 Seconds to enter their

enter their name you have 5 Seconds to enter your

name you have 5 Seconds to enter your name we will create a

name we will create a prompt enter your

prompt enter your name I'll use print rather than and

name I'll use print rather than and print

print line we will assign a string variable of

line we will assign a string variable of name use our scanner called the next

name use our scanner called the next line

line method and then once we have the name

method and then once we have the name we'll

we'll output hello plus the user's name hello

output hello plus the user's name hello plus name so let's do a test run

plus name so let's do a test run currently we don't have a timer

currently we don't have a timer setup you have 5 Seconds down to your

setup you have 5 Seconds down to your name I can type in a name hit enter we

name I can type in a name hit enter we display hello the name and then the

display hello the name and then the program exits processed finished with

program exits processed finished with exit Code Zero if we were creating some

exit Code Zero if we were creating some sort of timer we could do the

sort of timer we could do the following to make this simple we could

following to make this simple we could use a for Loop the for Loop is going to

use a for Loop the for Loop is going to cycle five times we will have an index

cycle five times we will have an index of I in I equals 1 that's where we'll

of I in I equals 1 that's where we'll start we'll continue as long as I is

start we'll continue as long as I is less than or equal to 5 and then

less than or equal to 5 and then increment I by One during each cycle of

increment I by One during each cycle of the for Loop to mimic waiting for one

the for Loop to mimic waiting for one second you can access the thread class

second you can access the thread class call the Sleep Method pass in 1,000

call the Sleep Method pass in 1,000 milliseconds when you use thread that

milliseconds when you use thread that refers to the current thread that we're

refers to the current thread that we're working with in this case the main

working with in this case the main thread which is what our main program

thread which is what our main program runs on but since our thread might be

runs on but since our thread might be interrupted we do need a try and catch

interrupted we do need a try and catch block because this is considered

block because this is considered dangerous code we will try this code

dangerous code we will try this code where we will have our main Java thread

where we will have our main Java thread sleep for 1,000 milliseconds

sleep for 1,000 milliseconds and we will catch the following

and we will catch the following exception an interrupted

exception an interrupted exception So within our catch block we

exception So within our catch block we will catch any interrupted exceptions

will catch any interrupted exceptions which we will name e if our thread is

which we will name e if our thread is interrupted we will

interrupted we will say thread was

interrupted in our imaginary timer we'll need an exit

need an exit condition let's say if our index of I is

condition let's say if our index of I is equal to 5

equal to 5 that means times up so we'll

that means times up so we'll output times up I'm going to show you

output times up I'm going to show you why this won't work the way that we

why this won't work the way that we think we have 5 Seconds to enter our

think we have 5 Seconds to enter our name but there's no prompt or

name but there's no prompt or anything then we get the message times

anything then we get the message times up and only after that Loop is complete

up and only after that Loop is complete are we allowed to enter our name and

are we allowed to enter our name and then we can type in our name we get the

then we can type in our name we get the output of hello our name and then the

output of hello our name and then the program exits so the problem that we're

program exits so the problem that we're running into is that all of this code is

running into is that all of this code is running on our main thread we have 5

running on our main thread we have 5 Seconds to enter our name but we can't

Seconds to enter our name but we can't reach that code until the 5 seconds are

reach that code until the 5 seconds are up because our main thread is waiting

up because our main thread is waiting for this Loop to finish so what we could

for this Loop to finish so what we could do is create a separate thread where

do is create a separate thread where we're counting to five and our main

we're counting to five and our main thread is going to be in charge of

thread is going to be in charge of accepting our user input so here's how

accepting our user input so here's how to create another thread we're going to

to create another thread we're going to extend the runable interface to create a

extend the runable interface to create a runnable object

runnable object let's go to file new Java class this

let's go to file new Java class this will be a class we'll name this class my

will be a class we'll name this class my runnable or something unique that's

runnable or something unique that's relevant to what you're

relevant to what you're creating my runnable is going to

creating my runnable is going to implements because we're working with

implements because we're working with interfaces the runnable

interfaces the runnable interface if you implement an interface

interface if you implement an interface it's kind of like you're signing a

it's kind of like you're signing a contract we have to override any

contract we have to override any required method me we need to override

required method me we need to override the run method we need the at override

the run method we need the at override annotation then we will override the run

annotation then we will override the run method public void

method public void run within this run method we're going

run within this run method we're going to add any code we want to run in the

to add any code we want to run in the background on a separate thread going

background on a separate thread going back to our main Java file we're going

back to our main Java file we're going to cut this

to cut this Loop and then paste it within the run

Loop and then paste it within the run method when we call this run method

method when we call this run method we'll have this countdown timer run

we'll have this countdown timer run running in the background on a separate

running in the background on a separate thread any code you want to run on a

thread any code you want to run on a separate thread place within the run

separate thread place within the run method all right going back to our main

method all right going back to our main Java file we'll tell the user they have

Java file we'll tell the user they have 5 Seconds to enter their

5 Seconds to enter their name we have our class of my runnable we

name we have our class of my runnable we will create a my runnable object or

will create a my runnable object or whatever it is that you named to this

whatever it is that you named to this class let's say my runnable will be the

class let's say my runnable will be the name of the object equals new my

name of the object equals new my runable we will take this runnable

runable we will take this runnable object pass it into the Constructor of

object pass it into the Constructor of the thread class here's where we're

the thread class here's where we're going to create a new thread thread

going to create a new thread thread thread equals new

thread equals new thread pass in your runnable object as

thread pass in your runnable object as an argument to the thread

an argument to the thread Constructor now we just need our thread

Constructor now we just need our thread to

to start you'll take your thread call the

start you'll take your thread call the start method and this should work let's

start method and this should work let's try

try it you have 5 Seconds to enter your name

it you have 5 Seconds to enter your name and we get that prompt of enter your

and we get that prompt of enter your name but I'm not going to type in

name but I'm not going to type in anything we get the message times up

anything we get the message times up because we ran out of

because we ran out of time let's try it again I'll type in my

time let's try it again I'll type in my name this

name this time there we go we get our output hello

time there we go we get our output hello bro then we get the message time is

bro then we get the message time is up both these threads are running at the

up both these threads are running at the same time the code within our run method

same time the code within our run method is running on a separate thread it's

is running on a separate thread it's running in the background while our main

running in the background while our main program is running running so that's why

program is running running so that's why threads are useful so let me extend this

threads are useful so let me extend this time let's say 10

time let's say 10 seconds if I is equal to 10 just to give

seconds if I is equal to 10 just to give us some more

us some more time you have 10 seconds to enter your

time you have 10 seconds to enter your name now check this

name now check this out you have 10 seconds to to your name

out you have 10 seconds to to your name I'll type in my name immediately we get

I'll type in my name immediately we get the output hello whatever your name is

the output hello whatever your name is but the program is still running because

but the program is still running because that second thread is still running in

that second thread is still running in the background

the background our program doesn't exit until all

our program doesn't exit until all threads are

threads are done if your main thread is done you can

done if your main thread is done you can end all other threads but you'll want to

end all other threads but you'll want to set those threads to be what is known as

set those threads to be what is known as Damon threads a Damon thread will end

Damon threads a Damon thread will end when the main thread is over we will

when the main thread is over we will take our thread call the set Damon

take our thread call the set Damon method pass and

method pass and true this thread is going to end as soon

true this thread is going to end as soon as our main thread is finished let's try

as our main thread is finished let's try it again you have 10 seconds then to

it again you have 10 seconds then to your name I'll type in my name we get

your name I'll type in my name we get our output and then our program exits

our output and then our program exits without saying time is up processed

without saying time is up processed finished with exit code

finished with exit code zero that's because we set our second

zero that's because we set our second thread to be a Damon thread it ends when

thread to be a Damon thread it ends when the main thread is over now on the other

the main thread is over now on the other hand let's say that we wait for time to

hand let's say that we wait for time to be up we wait the full 10

seconds time's up our program isn't over yet we're still waiting for user input

yet we're still waiting for user input and I can still type it

and I can still type it in hello bro process finished with exit

in hello bro process finished with exit Code Zero optionally what you could do

Code Zero optionally what you could do to get your program to exit go to your

to get your program to exit go to your runnable class wherever you would like

runnable class wherever you would like your program to exit when seconds equals

your program to exit when seconds equals 10 that's where I would like to exit to

10 that's where I would like to exit to exit the program prematurely I can

exit the program prematurely I can access system called the exit method

access system called the exit method pass in an exit code of zero that will

pass in an exit code of zero that will ENT the program all right let's try this

ENT the program all right let's try this again you have 10 seconds to end to your

again you have 10 seconds to end to your name I'm not going to type in anything

name I'm not going to type in anything I'm just going to wait for the full 10

seconds time's up and then our program exits but that's what we want though the

exits but that's what we want though the way that we've set up this program is

way that we've set up this program is that we want this program to exit either

that we want this program to exit either when we finish typing in our name or we

when we finish typing in our name or we run out of

run out of time all right everybody so that is an

time all right everybody so that is an introduction to in it allows a program

introduction to in it allows a program to run multiple tasks simultaneously it

to run multiple tasks simultaneously it helps to improve performance with

helps to improve performance with timeconsuming

timeconsuming operations it's useful with file input

operations it's useful with file input and output operations network

and output operations network communications or any other background

communications or any other background tasks and well everybody that is an

tasks and well everybody that is an introduction to threading in Java yo we

introduction to threading in Java yo we finally made it to multi-threading in

finally made it to multi-threading in Java multi-threading enables a program

Java multi-threading enables a program to run multiple threads concurrently at

to run multiple threads concurrently at the same time as we've talked about in

the same time as we've talked about in the previous lesson a thread is a set of

the previous lesson a thread is a set of instructions and they run independently

instructions and they run independently from other threads multi-threading is

from other threads multi-threading is useful for background tasks or other

useful for background tasks or other timeconsuming

timeconsuming operations in the prior lesson we've

operations in the prior lesson we've learned that there's two ways to create

learned that there's two ways to create threads we can either extend the thread

threads we can either extend the thread class or implement the runable interface

class or implement the runable interface the second option is better in most

the second option is better in most cases because we're not limited by

cases because we're not limited by single inheritance here's how we can get

single inheritance here's how we can get started multi-threading we're going to

started multi-threading we're going to create a new class file new Java class

create a new class file new Java class we'll call this class my

runnable my runnable will implements the runnable interface if

implements the runnable interface if we're implementing an interface it's

we're implementing an interface it's kind of like we're signing a contract we

kind of like we're signing a contract we have to override any required methods we

have to override any required methods we have to override the run

have to override the run method public void

method public void run whatever is within the run method

run whatever is within the run method this is the code that's going to perform

this is the code that's going to perform when this thread is up and running

when this thread is up and running so what would we like to do just for a

so what would we like to do just for a beginner's example let's count to five

beginner's example let's count to five using a four Loop we'll write a for

using a four Loop we'll write a for Loop we will create an index of I I'll

Loop we will create an index of I I'll set that equal to be one right away

set that equal to be one right away we'll continue as long as I is less than

we'll continue as long as I is less than or equal to 5 cuz we're counting to five

or equal to 5 cuz we're counting to five then increment I by 1 during each cycle

then increment I by 1 during each cycle this for loop I would like this thread

this for loop I would like this thread to wait for 1 second before printing

to wait for 1 second before printing whatever I is what whatever the current

whatever I is what whatever the current count is if we're counting we will

count is if we're counting we will access the thread class called The Sleep

access the thread class called The Sleep Method pass in 1,000 milliseconds to

Method pass in 1,000 milliseconds to sleep for a

sleep for a second we will need to surround this

second we will need to surround this method with try and catch

method with try and catch blocks we'll catch any interrupted

blocks we'll catch any interrupted exceptions but let's output the

exceptions but let's output the following we'll say thread was

following we'll say thread was interrupted after our thread sleeps for

interrupted after our thread sleeps for 1 second let's display the current count

1 second let's display the current count I'll just say I just to keep it

I'll just say I just to keep it simple let's go back to our main Java

simple let's go back to our main Java file we'll need to create a runable

file we'll need to create a runable object my

object my runable let's say my runable equals new

runable let's say my runable equals new my

runable we have to pass in this runable object to a thread object let's say

object to a thread object let's say thread thread equals new thread we will

thread thread equals new thread we will pass in our runable object

pass in our runable object to get this thread to start we have to

to get this thread to start we have to call the start method of our thread

call the start method of our thread thread. start

thread. start method and this should work we'll test

method and this should work we'll test it 1 2 3 4 5 and then we exit the

it 1 2 3 4 5 and then we exit the program another shortcut you can do too

program another shortcut you can do too instead of creating a named runable

instead of creating a named runable object we can pass in an anonymous

object we can pass in an anonymous renable object to the thread Constructor

renable object to the thread Constructor so let's copy this section delete this

so let's copy this section delete this line of code and then pass in a new

line of code and then pass in a new runable

runable object this will work too and it's a lot

object this will work too and it's a lot more

concise now we won't have just one thread we'll have two so let's rename

thread we'll have two so let's rename thread as thread one copy this line of

thread as thread one copy this line of code paste it rename the second thread

code paste it rename the second thread as thread two thread 1. start and thread

as thread two thread 1. start and thread 2. start

2. start so now we'll have two threads running at

so now we'll have two threads running at the same time they're running

concurrently so they both say 1 2 3 4 5 we have successfully

we have successfully multi-threaded you could differentiate

multi-threaded you could differentiate these by getting their name here's an

these by getting their name here's an example to get each thread's name we're

example to get each thread's name we're going to access the thread class called

going to access the thread class called the current thread method

the current thread method and then method chain the get name

and then method chain the get name method then I'll add a space plus our

method then I'll add a space plus our counter

counter RI just so we can see each thread by its

RI just so we can see each thread by its name and what it's counting exactly okay

name and what it's counting exactly okay let's try this

let's try this again we have thread one and thread zero

again we have thread one and thread zero now they won't always be in the same

now they won't always be in the same order they're running

order they're running independently thread zero that's our

independently thread zero that's our thread one Java's thread one is our

thread one Java's thread one is our thread

two okay here's an exercise we're going to have thread one say ping and thread 2

to have thread one say ping and thread 2 say pong like we're playing a game of

say pong like we're playing a game of pingpong we'll modify the my runnable

pingpong we'll modify the my runnable class we'll need some text a text

class we'll need some text a text variable we'll say private final we

variable we'll say private final we don't want it to

don't want it to change string text then we'll need a

change string text then we'll need a Constructor to assign it my

Constructor to assign it my runnable we have one parameter a string

runnable we have one parameter a string of text we will assign this. text equals

of text we will assign this. text equals the text we

the text we receive instead of printing our counter

receive instead of printing our counter we'll print our

we'll print our text all right and that's all we need

text all right and that's all we need going back to our main Java file we have

going back to our main Java file we have to pass in some text when we construct a

to pass in some text when we construct a runable

runable object for the first thread we'll we'll

object for the first thread we'll we'll say ping for the second thread we'll say

say ping for the second thread we'll say pong so here's what we have

program before we start the threads let's say game start there's one more

let's say game start there's one more thing I want to show you game

start after we start the threads let's try and say game

try and say game over game over here's what

over game over here's what happens game start game over and our two

happens game start game over and our two threads are still

threads are still running then we

running then we finish so the problem here is that in

finish so the problem here is that in our main thread it doesn't Wait For

our main thread it doesn't Wait For Thread one and thread two to

Thread one and thread two to finish our main thread ends

finish our main thread ends immediately we can have our main thread

immediately we can have our main thread wait for these threads to finish by

wait for these threads to finish by calling the join method of each thread

calling the join method of each thread our main thread we'll wait for these two

our main thread we'll wait for these two threads to

threads to finish after these two threads start

finish after these two threads start we'll use each join method thread 1.

we'll use each join method thread 1. join and thread 2

dojin and we do have to surround these with try and catch

blocks try thread 1. jooin and thread 2 do jooin if our main thread is

do jooin if our main thread is interrupted we'll output main thread was

interrupted we'll output main thread was interrupted okay this should work now

interrupted okay this should work now before we display game over we're going

before we display game over we're going to wait for our two threads to

to wait for our two threads to finish here's what we got game start and

finish here's what we got game start and we display

we display pingpong and we'll do that five times

pingpong and we'll do that five times and then display game

and then display game over all right everybody that is an

over all right everybody that is an introduction to multi-threading

introduction to multi-threading it enables a program to run multiple

it enables a program to run multiple threads concurrently a thread is a set

threads concurrently a thread is a set of instructions that run independently

of instructions that run independently multi-threading is useful for background

multi-threading is useful for background tasks or other timeconsuming

tasks or other timeconsuming operations and well everybody that is an

operations and well everybody that is an introduction to multi-threading in Java

introduction to multi-threading in Java hey everybody in this video we're going

hey everybody in this video we're going to create a working alarm clock that

to create a working alarm clock that plays music using

Java all right let's get started everybody this alarm clock is going to

everybody this alarm clock is going to to serve as a final project for us will

to serve as a final project for us will combine a lot of Concepts that we've

combine a lot of Concepts that we've learned throughout the series when

learned throughout the series when starting a new project a good first step

starting a new project a good first step is to declare all your variables or

is to declare all your variables or other objects that you'll need

other objects that you'll need throughout this program we'll begin with

throughout this program we'll begin with the scanner because we'll be accepting

the scanner because we'll be accepting user input a user is going to enter in a

user input a user is going to enter in a Time scanner scanner equals new scanner

Time scanner scanner equals new scanner pass in

pass in system.in and we'll be importing classes

system.in and we'll be importing classes as we go along at the end of this

as we go along at the end of this program we're going to close our scan

program we're going to close our scan but we'll actually move it later on

but we'll actually move it later on because our alarm clock class is

because our alarm clock class is actually going to be using it more on

actually going to be using it more on that later we have our scanner and

that later we have our scanner and currently we're closing it a user is

currently we're closing it a user is going to use the scanner and enter in

going to use the scanner and enter in hours minutes and seconds to set the

hours minutes and seconds to set the alarm when the user types in a string

alarm when the user types in a string representation of a time we need to

representation of a time we need to parse it into a local time object but

parse it into a local time object but we'll need a formatter object we will

we'll need a formatter object we will create a date time formatter object

create a date time formatter object you'll need to import this class too

you'll need to import this class too we'll name this object

we'll name this object formatter

formatter equals we will access the class of

equals we will access the class of datetime formatter called the of pattern

datetime formatter called the of pattern method within this method we have to

method within this method we have to pass in a pattern a pattern that

pass in a pattern a pattern that represents the time for hours minutes

represents the time for hours minutes and seconds within a string we will pass

and seconds within a string we will pass in two Capital H's for hours colon two

in two Capital H's for hours colon two lowercase M for minutes colon two

lowercase M for minutes colon two lowercase s's for

lowercase s's for seconds when a user types in a string

seconds when a user types in a string representation of a time using our

representation of a time using our scanner we'll use this formatter object

scanner we'll use this formatter object when we parse it into a Time

when we parse it into a Time object then we will create a local time

object then we will create a local time object which we will name alarm

object which we will name alarm time we'll instantiate that later import

time we'll instantiate that later import this

this class now we'll need a user to enter in

class now we'll need a user to enter in the time we'll create a

the time we'll create a prompt enter n alarm time we'll give

prompt enter n alarm time we'll give them a prompt for this format hours

them a prompt for this format hours minutes

minutes seconds let me switch this to print CU I

seconds let me switch this to print CU I like it on the same

line let's create a string variable of let's name this input time

variable of let's name this input time equals use our

equals use our scanner call the next next line method

scanner call the next next line method to get a line of text from the

to get a line of text from the user all right now here's where we're

user all right now here's where we're going to parse our string our input time

going to parse our string our input time and assign it to our alarm time object

and assign it to our alarm time object so we have to convert it we have to

so we have to convert it we have to parse it we will assign our alarm time

parse it we will assign our alarm time object set it equal to access the class

object set it equal to access the class of local time and there is a parse

of local time and there is a parse method we have to pass in two arguments

method we have to pass in two arguments the first is a string representation of

the first is a string representation of our

our time and our format object that we have

time and our format object that we have previously declared and

previously declared and instantiated then we'll output the

instantiated then we'll output the following

following message alarm set

message alarm set 4 plus our alarm time we can output it

4 plus our alarm time we can output it directly let's do a test

run let's say I set my alarm for 730 this is going to be in military time

730 this is going to be in military time alarm set for

7:30 what if we type in a time that doesn't make

doesn't make sense uh like the word

sense uh like the word Pizza well we encounter an exception a

Pizza well we encounter an exception a date time parse exception we can use

date time parse exception we can use exception handling to catch this

exception handling to catch this exception I'm just going to copy it and

exception I'm just going to copy it and then paste it

then paste it later this portion is considered

later this portion is considered dangerous code we can put that within a

dangerous code we can put that within a try block try this dangerous code catch

try block try this dangerous code catch and any of the following

and any of the following exceptions we will catch that date time

exceptions we will catch that date time parse exception which we will name

parse exception which we will name e import this

e import this class okay then take all of this

class okay then take all of this previous code stick it within our Tri

previous code stick it within our Tri block we will try this code and catch

block we will try this code and catch this exception if it pops up we'll

this exception if it pops up we'll output the following let's say invalid

hours minutes seconds let me change that to

use I've already used Pizza let's go with Taco for the alarm time invalid

with Taco for the alarm time invalid format please use hours minutes

format please use hours minutes seconds let's try

seconds let's try 8:00 alarm set for

8:00 alarm set for 8:00 all right good we know that that

8:00 all right good we know that that works why don't we prompt the user to

works why don't we prompt the user to enter in the time again if it is an

enter in the time again if it is an invalid format we can use a while

invalid format we can use a while loop while some condition is true

loop while some condition is true continue to do the following let's cut

continue to do the following let's cut our code our trying catch blocks stick

our code our trying catch blocks stick it within the while loop what's our

it within the while loop what's our condition while our alarm time is empty

condition while our alarm time is empty there's actually a value that you can

there's actually a value that you can assign an object and that is null null

assign an object and that is null null has no value

has no value within our while loop we'll continue

within our while loop we'll continue this while loop while our alarm time is

this while loop while our alarm time is equal to a value of

null so if I were to just hit enter we get an invalid format please use hours

get an invalid format please use hours minute seconds and it won't let me

minute seconds and it won't let me continue until I enter in a valid

continue until I enter in a valid time so I will set this to be

time so I will set this to be 9:00 and then our alarm is set for

9:00 and then our alarm is set for 9:00 the first section of this project

9:00 the first section of this project is complete we have successfully set an

is complete we have successfully set an alarm time our alarm time is a local

alarm time our alarm time is a local time object the next part is to create

time object the next part is to create an alarm clock class to create alarm

an alarm clock class to create alarm clock objects we're going to create an

clock objects we're going to create an alarm clock class file new Java class we

alarm clock class file new Java class we will name this class alarm

clock we're going to have our alarm clock run on a separate thread to do

clock run on a separate thread to do that we can implement

that we can implement the runnable

the runnable interface so we can do some threading

interface so we can do some threading but if we implement the runable

but if we implement the runable interface it's kind of like we're

interface it's kind of like we're signing a contract we have to override

signing a contract we have to override the run method public void

the run method public void run when this alarm clock is running on

run when this alarm clock is running on a separate thread it's going to execute

a separate thread it's going to execute any code within the run method but we're

any code within the run method but we're going to fill that in later currently

going to fill that in later currently our alarm clock needs one thing it needs

our alarm clock needs one thing it needs an alarm time

an alarm time which we will send it from the main Java

which we will send it from the main Java file let's set that up as a

file let's set that up as a field with our alarm time I'm going to

field with our alarm time I'm going to make it private I only want the alarm

make it private I only want the alarm clock class to be able to change it I

clock class to be able to change it I will also make it final it's

will also make it final it's unchangeable the data type it's an

unchangeable the data type it's an object it's a local time object which we

object it's a local time object which we will name alarm time and then we do need

will name alarm time and then we do need to import this class too

to import this class too all right then we need a

all right then we need a Constructor we will take our alarm

Constructor we will take our alarm clock we need one parameter

clock we need one parameter currently a local time of alarm time we

currently a local time of alarm time we will assign this do alarm time equals

will assign this do alarm time equals the alarm time that we

the alarm time that we receive all right that's

receive all right that's good okay let's go back to our main Java

good okay let's go back to our main Java file before we close our scanner we're

file before we close our scanner we're going to create an alarm clock

going to create an alarm clock object alarm clock is the class we will

object alarm clock is the class we will name this object alarm clock equals new

name this object alarm clock equals new alarm clock but the way that we set up

alarm clock but the way that we set up this class is that we have to pass in an

this class is that we have to pass in an alarm time a local time

alarm time a local time object we have our alarm time we've

object we have our alarm time we've already verified it using this while

already verified it using this while loop it should be a valid format we will

loop it should be a valid format we will pass in our local time of alarm time to

pass in our local time of alarm time to the alarm clock in order to construct it

the alarm clock in order to construct it since our alarm clock is going to be

since our alarm clock is going to be running on a separate thread we'll have

running on a separate thread we'll have to create a new

to create a new thread thread let's name this alarm

thread thread let's name this alarm thread equals a new thread and then

thread equals a new thread and then we'll pass in our alarm clock we can do

we'll pass in our alarm clock we can do this because our alarm clock it

this because our alarm clock it implements the runnable interface so our

implements the runnable interface so our alarm clock is going to run on a

alarm clock is going to run on a different thread than the main thread to

different thread than the main thread to start a thread you will take your thread

start a thread you will take your thread in this case alarm thread called the

in this case alarm thread called the start

start method so once we start our alarm thread

method so once we start our alarm thread it's going to execute the run method all

it's going to execute the run method all right so for testing purposes let's get

right so for testing purposes let's get the time right now to get the time right

the time right now to get the time right now we will create a local time object

now we will create a local time object let's just call it now what's the time

let's just call it now what's the time right now equals access the class of

right now equals access the class of local time called the now method I will

local time called the now method I will display the time right now just for

display the time right now just for testing purposes I want to be sure that

testing purposes I want to be sure that our alarm clock class is

working so we have to enter in a valid alarm time I'll just set it to be 8:00

alarm time I'll just set it to be 8:00 a.m. alarm is set and here's the current

a.m. alarm is set and here's the current time right now at least for me I'm

time right now at least for me I'm filming this video at 7:26 in the

filming this video at 7:26 in the morning it is going to be in military

morning it is going to be in military time and then we have a bunch of

time and then we have a bunch of milliseconds after we know that we're

milliseconds after we know that we're successfully calling the run method

so we have the time right now we're going to compare times is the time right

going to compare times is the time right now before our alarm time if it is we'll

now before our alarm time if it is we'll continue sleeping we'll have our thread

continue sleeping we'll have our thread sleep we can delete this print statement

sleep we can delete this print statement I was just testing

I was just testing it we need to check if the time right

it we need to check if the time right now is before the alarm time if it is

now is before the alarm time if it is we'll continue

we'll continue waiting we can do this with the while

waiting we can do this with the while loop take our time right

loop take our time right now call the is before method we can

now call the is before method we can compare local times is the time right

compare local times is the time right now before our alarm

now before our alarm time if it is we're going to sleep for 1

time if it is we're going to sleep for 1 second access the thread class sleep for

second access the thread class sleep for 1,000

milliseconds all right we do need to surround this with a TR and catch block

surround this with a TR and catch block let's do

let's do that try and sleep for 1,000

that try and sleep for 1,000 milliseconds

milliseconds if this thread is interrupted we'll

if this thread is interrupted we'll output the

output the following thread was

following thread was interrupted this is if we encounter an

interrupted this is if we encounter an interrupted

interrupted exception we're checking the time right

exception we're checking the time right now is it before our alarm time if it is

now is it before our alarm time if it is let's output the time currently I'm

let's output the time currently I'm going to condense some of this code

going to condense some of this code outside of our while loop we're already

outside of our while loop we're already creating an object of now so why don't

creating an object of now so why don't we do this let's cut this line

and do the following access the class of local time call the now method and then

local time call the now method and then method chain the is before

method chain the is before method basically every second we're

method basically every second we're going to get the time right now and

going to get the time right now and compare it to our alarm time is the time

compare it to our alarm time is the time right now before our alarm time if this

right now before our alarm time if this while loop is running we'll output the

while loop is running we'll output the time so we'll output

time so we'll output local time called the now

local time called the now method let's do a test

run ENT turn an alarm time I'll just say 8:00 a.m. to keep it

8:00 a.m. to keep it simple alarm set for 8 a.m. and here's

simple alarm set for 8 a.m. and here's the current time it updates every 1

the current time it updates every 1 second approximately every 1

second approximately every 1 second now let's do some formatting

second now let's do some formatting because I don't like all these

because I don't like all these milliseconds afterwards

here's what we could do we could create an integer variable of ours set it equal

an integer variable of ours set it equal to access the class of local

to access the class of local time called the now method then method

time called the now method then method chain the get hour method to return the

chain the get hour method to return the number of

number of hours then we're going to do this with

hours then we're going to do this with minutes int minutes get

minutes int minutes get minute int second

second okay I'm going to show you what happens if I print ours plus a

colon plus minutes plus a colon

again plus seconds here's what we have currently

I will set this to be 8 a.m. alarm set for 8 a.m. so this looks

a.m. alarm set for 8 a.m. so this looks pretty good but I would like some

pretty good but I would like some leading

zeros we could do that with print F so let's switch this

let's switch this around print

around print f for print F We'll add some

f for print F We'll add some placeholders which we can use with a

placeholders which we can use with a percent sign to display two leading

percent sign to display two leading zeros we can use

zeros we can use 02 if we're going to insert an integer

02 if we're going to insert an integer we have to use D for decimal so let's do

we have to use D for decimal so let's do this three times 02 D percent 02

this three times 02 D percent 02 D we are inserting hours minutes and

D we are inserting hours minutes and seconds let's try it

seconds let's try it again I will set the time to be 8:00

again I will set the time to be 8:00 a.m.

oh and then I'm forgetting the colons and a new line

character so let's insert some colons and then add a new line character

colons and then add a new line character to the end because I forgot to do

that that's much better and we have that leading zero if one of these values is

leading zero if one of these values is one digit that looks pretty good now

one digit that looks pretty good now what we'll do rather than updating the

what we'll do rather than updating the time and placing it on a new line every

time and placing it on a new line every 1,000 milliseconds we're going to edit

1,000 milliseconds we're going to edit it in

it in place here's how with our print F

place here's how with our print F statement we're going to insert back SLR

statement we're going to insert back SLR this is for carriage return it'll move

this is for carriage return it'll move the cursor back to the beginning and

the cursor back to the beginning and then we'll get rid of the new line

then we'll get rid of the new line character it should look something like

character it should look something like this now

our time is going to update in place rather than take up a new line for each

rather than take up a new line for each time it

time it updates I think this looks a lot

better all right so we're going to condense some of these steps instead of

condense some of these steps instead of accessing the local time class three

accessing the local time class three separate times let's just do it once

separate times let's just do it once we'll create a local time object named

we'll create a local time object named now

now equals access the class of local time

equals access the class of local time call the now

method when we assign ours we will access our object of now now is our

access our object of now now is our local time now. getet hour for minutes

local time now. getet hour for minutes now doget minute and seconds now. getet

now doget minute and seconds now. getet second and then we'll insert them using

second and then we'll insert them using our printf

our printf statement or even instead of assigning

statement or even instead of assigning variables we could just call now doget

variables we could just call now doget hour now. get

hour now. get minute and now. getet second and we can

minute and now. getet second and we can delete these variables cuz we don't need

delete these variables cuz we don't need them just for readability I'll place

them just for readability I'll place these on a new

up all right this should work too let's make

sure yes it does you can keep this code the way it was

you can keep this code the way it was before but I like it a little more

before but I like it a little more concise all right our while loop is

concise all right our while loop is done so once we escape the while loop

done so once we escape the while loop that means the local time is our alarm

that means the local time is our alarm time or past our alarm time so for

time or past our alarm time so for testing purposes let's output the

testing purposes let's output the following let's just say alarm

following let's just say alarm noises we haven't added any audio yet

for my alarm time I'm just going to set it to be 1 minute past what it is

it to be 1 minute past what it is currently in this case 7:44 but pick a

currently in this case 7:44 but pick a different time depending on what time it

different time depending on what time it is for you

is for you currently so I just need to wait for 20

seconds all right once we reach our alarm time or it's past our alarm time

alarm time or it's past our alarm time we display alarm noises and then exit

we display alarm noises and then exit the

the program I'm going to add a new line

program I'm going to add a new line character just before we display alarm

character just before we display alarm noises for our alarm we'll be playing

noises for our alarm we'll be playing some music later just for now we're

some music later just for now we're going to play a single beep just to be

going to play a single beep just to be sure that everything is working

sure that everything is working basically to have Java make a beep noise

basically to have Java make a beep noise you can do the following access the

you can do the following access the class of tool kit call the

class of tool kit call the get

get default toolkit

default toolkit method call the beep method and then we

method call the beep method and then we do need to import this

do need to import this class once we escape the wild Loop we

class once we escape the wild Loop we will display alarm noises and make a

will display alarm noises and make a beep sound a single

minute there we go we display our text of alarm noises

go we display our text of alarm noises and hopefully you heard that beep so we

and hopefully you heard that beep so we know that our alarm arm clock is working

know that our alarm arm clock is working to make a more sophisticated version

to make a more sophisticated version we're going to play an audio

we're going to play an audio file I have an audio file here it's a

file I have an audio file here it's a wave file the following code isn't going

wave file the following code isn't going to be compatible with MP3s if you do

to be compatible with MP3s if you do have an MP3 file you can always use an

have an MP3 file you can always use an online MP3 to wave converter that's what

online MP3 to wave converter that's what I did to make this convenient for me I'm

I did to make this convenient for me I'm going to place this wave file within my

going to place this wave file within my project

project folder here's my wave file going back to

folder here's my wave file going back to our main Java file I will create a

our main Java file I will create a string variable a file path string file

string variable a file path string file path

path equals here I can list a relative file

equals here I can list a relative file path or an absolute file path this wave

path or an absolute file path this wave file is within my project folder I just

file is within my project folder I just need to list the file name so I'm going

need to list the file name so I'm going to copy

to copy path file

path file name and paste it within that

name and paste it within that string with our alarm clock we're going

string with our alarm clock we're going to send it our file path we'll send it

to send it our file path we'll send it as the second argument along with the

as the second argument along with the alarm time but we have to set up the

alarm time but we have to set up the Constructor so that we can accept

it with our alarm clock class we will create a private final string of file

create a private final string of file path then we'll have to set up the

path then we'll have to set up the parameters we are also accepting a

parameters we are also accepting a string of file path the location to that

string of file path the location to that file to play the

file to play the audio this. file file

audio this. file file path equals the file path that we

path equals the file path that we receive with playing audio there's a lot

receive with playing audio there's a lot of code we have to write I'll dedicate

of code we have to write I'll dedicate an entire method just to playing

an entire method just to playing audio let's make this a private method

audio let's make this a private method so only our alarm clock can access it

so only our alarm clock can access it it's not going to return anything the

it's not going to return anything the return type is void let's name this

return type is void let's name this method play

sound once we reach the end we will call the play sound

the play sound method but we're going to pass in our

method but we're going to pass in our file

file path so we need a parameter setup of

path so we need a parameter setup of string file

string file path and now we are within the play

path and now we are within the play sound

sound method to play a w file we're going to

method to play a w file we're going to create a file object named audio file

create a file object named audio file equals a new file and then pass in our

equals a new file and then pass in our file path

import this class we'll be doing a lot of importing

class we'll be doing a lot of importing as we go

as we go along then we need to create an audio

along then we need to create an audio input

input stream audio input

stream audio input stream we'll name this audio

stream we'll name this audio stream

stream equals access the class of audio

equals access the class of audio system called the get audio input stream

system called the get audio input stream method

method yes that's a lot to

yes that's a lot to type then we will pass in our audio

type then we will pass in our audio file import this

class import the class for audio system to there's a lot of different exceptions

to there's a lot of different exceptions that we'll need to catch such as if our

that we'll need to catch such as if our audio file is unsupported like it's an

audio file is unsupported like it's an MP3 file we'll need some try and catch

MP3 file we'll need some try and catch blocks try this code catch any

blocks try this code catch any exceptions

exceptions here's one we'll start

with we will catch any un supported audio file

supported audio file exceptions which we will name e import

exceptions which we will name e import this

class if we encounter this exception we'll output the

we'll output the following audio file format is not

following audio file format is not supported

if the audio is unavailable for some reason let's say another resource is

reason let's say another resource is accessing it we can catch that

accessing it we can catch that too that exception is a

too that exception is a line unavailable exception line

line unavailable exception line unavailable exception of

unavailable exception of e let's say something like audio is

unavailable import the class then as a safety net

class then as a safety net we will catch any IO exceptions input

we will catch any IO exceptions input output

output exceptions IO exception e here we'll

exceptions IO exception e here we'll just

just say error

say error reading audio file it is good to catch

reading audio file it is good to catch specific kinds of exceptions first which

specific kinds of exceptions first which we are doing this just acts as a safety

we are doing this just acts as a safety net so with modern Java you can try with

net so with modern Java you can try with resources you'll automatically close

resources you'll automatically close those resources when you're done with

those resources when you're done with them when we create our audio input

them when we create our audio input stream let's cut all this

stream let's cut all this code and paste it within the triy with

code and paste it within the triy with resources block then delete that

resources block then delete that semicolon so we have our audio stream we

semicolon so we have our audio stream we need to create a clip object a clip acts

need to create a clip object a clip acts as a player that plays an audio stream

as a player that plays an audio stream within the tri block we will create a

within the tri block we will create a clip object clip

clip object clip clip equals access the class of audio

clip equals access the class of audio system system called the get clip method

system system called the get clip method to create a clip

to create a clip object import this

class then we will use our clip and open our audio stream

object to get the clip to play we will call the start method of our clip

call the start method of our clip clip.art

clip.art method one issue we're probably going to

method one issue we're probably going to run into is that once we we start

run into is that once we we start playing the clip the program is going to

playing the clip the program is going to end immediately so we might not even

end immediately so we might not even hear it so temporarily I'm just going to

hear it so temporarily I'm just going to sleep for a couple

sleep for a couple seconds let's just sleep for 5

seconds let's just sleep for 5 seconds and then I do need to add a

seconds and then I do need to add a catch clause for any interrupted

catch clause for any interrupted exceptions we'll be deleting this don't

exceptions we'll be deleting this don't worry I just want to be sure that it

[Music] we played our music for 5 seconds and

we played our music for 5 seconds and then we exit the program what I would

then we exit the program what I would like to do instead is that we stop the

like to do instead is that we stop the alarm if we hit enter here's how we can

alarm if we hit enter here's how we can set that up we can delete this method

set that up we can delete this method where we sleep for 5 seconds instead

where we sleep for 5 seconds instead we'll wait for a user to hit enter and

we'll wait for a user to hit enter and delete that catch statement too

delete that catch statement too we're going to be using a scanner within

we're going to be using a scanner within a big project different parts of your

a big project different parts of your project may require different scanners

project may require different scanners but I like to just reuse the same one

but I like to just reuse the same one the problem with having multiple

the problem with having multiple scanners is if they use system.in and

scanners is if they use system.in and one scanner closes

one scanner closes it it's going to close system.in for all

it it's going to close system.in for all of them so rather than close the scanner

of them so rather than close the scanner at the end of our main Java file we're

at the end of our main Java file we're going to do that within the alarm clock

going to do that within the alarm clock class when everything is all done so

class when everything is all done so we'll do that at the end of the tri

we'll do that at the end of the tri block however our alarm clock class has

block however our alarm clock class has no idea what the scanner is we're going

no idea what the scanner is we're going to send it as an argument to the alarm

to send it as an argument to the alarm clock class so we'll need to set that up

clock class so we'll need to set that up we will pass in our scanner and reuse it

we will pass in our scanner and reuse it within the alarm clock

class within the alarm clock class we will create a private final scanner

will create a private final scanner object which we will name

object which we will name scanner import this

scanner import this class set up the

class set up the parameters we will receive a scanner

parameters we will receive a scanner object that we can use throughout the

object that we can use throughout the alarm clock

alarm clock class this do scanner equals the scanner

class this do scanner equals the scanner that we receive all right and now we

that we receive all right and now we have access to that same scanner the

have access to that same scanner the same one that we have instantiated at

same one that we have instantiated at the beginning of our

the beginning of our program and remember we are not closing

program and remember we are not closing it at the end of the main Java file

it at the end of the main Java file anymore

anymore once our alarm is playing we will wait

once our alarm is playing we will wait for some user input let's create a

for some user input let's create a prompt we'll say

prompt we'll say press

press enter to stop the

enter to stop the alarm I'm going to use

print we will use our scanner called the next line

next line method our music is going to continue

method our music is going to continue playing until we hit

playing until we hit enter once the user hits enter we we are

enter once the user hits enter we we are going to take our clip and call the stop

going to take our clip and call the stop method then close the scanner when we're

method then close the scanner when we're done with

done with it and that should be everything let's

it and that should be everything let's run this one last

to get our alarm to stop we just have to press

press [Music]

[Music] enter and the alarm stops and we exit

enter and the alarm stops and we exit the

the program all right everybody that is a

program all right everybody that is a working alarm clock that you can write

working alarm clock that you can write using Java

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