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Java Classes - How To Use Classes in Java



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we use classes in every single video but

we haven't talked about the actual class

itself I want to first say that I've

been getting a lot of comments asking me

how to think like a programmer so what I

did to help you out here as I put

together a little guide it's called 7

tips on how to think like a programmer

it's got lots of good information in it

here contains a method to how to

understand code even if you don't have

any prior experience

it's got tips on what the best

programmers in the world think so if you

want this 7 tips on how to think like a

programmer and just click the link in

the description and if you're new here

my name is Alex I post a Java tutorial

on this channel every single week for

you to understand Java and help you out

with your classes so if you might be

interested in that then please consider

subscribing so let's just start it off

by going to file new Java project we'll

call it our our project hit finish and

then open that up on the source folder

go to new class this creates the class

we want and I'm gonna call it class 1

and hit finish this generates some key

words to start letting us make a class a

class is a blueprint for an object in

objects let you do things in Java you

make a database object to get

information from a database update

information in a database Facebook has

an account object that has a user name

date of birth gender objects and

computers let you do things with them in

a class lets you make objects so without

classes there wouldn't be objects so

let's start building our class literally

all this in a class is things it knows

and things it can do aka variables and

methods let's start with variables

let's give class 1 an integer variable

called X say it's equal to 2 now this

class knows the variable 2 and to test

this out what we can do is make another

class with a main method goes to run

code you got to have a main method

somewhere and we don't want to clutter

this one right now so we'll just make a

new one we'll go to new class this one

will be called main and click the public

static void main

this adds this which runs code when we

the green run-button in here so what we

can do to test what class one knows is

make the object from it so to make an

object from a class you type the name

name it something and say equals new

that name

with parentheses the parentheses makes

it a constructor which means it makes

the object now if we print out C dot now

we see X C X whenever you put object dot

something it shows you all the things it

knows and things it can do variables up

here methods down here so it knows X so

if we save and run it and then we print

C dot X we'll just - you can have all

types of variables in here so you could

have say an array of character variables

if you want it and use it just the same

C dot chars beautiful so just with these

two lines of code we've created a class

that can now create objects and use what

it knows and what it can do let's delete

this chars because it's kind of getting

messy over here change that back you can

make multiple objects of the same class

too so we could say class one name is

something else and now we've got two

objects from the same class and now a

Dino's x2 so if we ran this we'd get to

two we create an object C from the class

one blueprint we create an object D from

the class one blueprint and then we

print C's X and DS X so this one class

can make multiple objects from it and

that's the real difference between

classes and objects objects are made

from the classes so now that we've shown

what the class knows let's do something

that the class can do with a method

we'll make a simple print method you

won't return anything so we're going to

type void here print hi

and then we'll just print out hi

now class one knows print hi so if we

did see dot we can do print hi no salute

this C dot print hi you can also do D

dot print hi but let's just do one now

we print hi from the C object from the

class one class that way you can also

have multiple classes so let's make

another one we'll call it class to know

main method because we already got one

say class two has integer y equals three

now we can do class two C equals new

class to print out C dot Y this will

print out what Y is which is three this

is really the basics of classes and

everything else all the other keywords

you see the weird logic and stuff that's

all extra so if you see like public

static boolean is valid with weird

parameters like this this is just a

method with keywords if you see things

like public final int Z equals that like

these are all keywords and you learn

what the keywords are public means it

has access to other files final means it

doesn't change type integer but it all

boils down to the basics variables and

methods inside of a class that objects

know when you make an object with the

class so that's really the basics I

don't want to go further into this

because that's really the concept here

the class can make multiple objects that

will all know the same variables and

methods there are concepts of super

classes and subclasses using

object-oriented programming terms but

just really understand what the

first super simple super basic variables

and methods hope this was helpful

remember to get my seven tips on how to

think like a programmer I really think

that'll help you out trust me I've been

through the same thing in my computer

science degree so I know what you're

going through

click the link in the description if you

want it I hope you have a great rest of

your day and I'll see you in the next

video

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