Java Tutorial for Beginners

foreign

and in this video we're going to talk

about core Java in this particular

course which is a lengthy video you're

going to learn everything from the

basics of core Java to the end of core

Java now this is not the first time I'm

uploading the video on Java if you can

see from last few years you will find

multiple Java playlist and multiple Java

full-fledged video but we all know right

the quality of videos are going up every

day plus the number of features being

added to a language is going up and

that's the reason I'm going to re-record

the entire course now this is a

full-fledged course and that's why it's

so lengthy but you cannot finish the

entire course in one day even if it says

12 hours or 13 hours it will take time

now let's talk about Java now why Java

is so famous now if you see the

programming index the top five

programming language you will always

find Java there maybe at the first

position or at the fourth position you

will find Java why Java is so famous is

because Java has multiple features which

helps it to be used in the Enterprise

Market I mean not just Enterprise Market

it can be used for mobile development

web development and of course Enterprise

application and most of the big

companies if you go there they are using

Java as their preferred language now in

Java we have a technology called jvm and

it's not just Java we have multiple

languages running on jvm so even if you

are working on some other language let's

say kotlin Scala groovy ultimately

you're working on Java technology and

that's why if you learn core Java it is

much easier for you to jump to different

languages and I've also observed

irrespective of which entry you are

going for it can be for development or

testing and that doesn't matter which

language your working on that maybe

python C sharp C plus plus they might

ask you Java questions because because

most of the interview questions are

based on Java because they feel that if

you know Java that means you know other

languages as well or you can learn other

languages easily as for my experience or

did I forgot to introduce myself uh my

name is Naveen Reddy I'm a corporate

trainer software developer and currently

focusing one on blockchain but Java is

my first love so I'm working on Java

from the last 12 years I've made

multiple courses on Java on YouTube and

different platforms and yeah I can teach

Java any day anytime

yeah sometimes I have to watch my own

videos to realize the concept but the

thing is I love Java and with this

experience I'm making the entire course

I was talking about my experience right

in fact I have learned multiple

languages in this all 12 years maybe I

have worked on 12 different languages

you can name it maybe C plus plus C

python Java JavaScript uh go language so

I love most of the languages some

languages are learned just for the

projects but then when I was learning

those languages I was I was feeling hey

it's it's so easy it's because

I have learned Java yes people say Java

is difficult just to start with it is

difficult maybe if you want to learn

Java as your first language it's kind of

difficult because if you're coming from

other languages let's say python or

JavaScript and if you want to print one

statement you can actually see that in

one line uh that's not the case with

Java right you have to write five lines

of code but yes once you make a big

application the number of lines will

remain almost same okay so Java is

difficult yes just to start with but the

thing is Java is one of the most

readable language what I mean by that is

if you are looking at someone else code

you can read the Java code line by line

uh that's not true with other languages

okay so Java is great in that terms Java

is maintainable and that maybe that's

why they most of the industries are

preferring to use Java now Java has

multiple features we'll talk about those

features later but just to name them we

got Voda which is right once one

anywhere which supports multiple

multi-threads it has a collection API

concept you can handle the exceptions

and we are going to learn everything in

this particular course now just to go

for the history of java Java was made in

1995 by sun microsystem and it was led

by the team of James Gosling later on

Oracle bought Sun so now the trademark

of java belongs to Reichel yes in

between Oracle did some messed up things

with Java but yeah they are back on

track and the beauty is Java is getting

updated every six months not the major

updates but they are working hard to

make Java as the most powerful language

so I hope you were excited for the

entire course we are going to start from

the basic as I mentioned and you will

learn a lot of Defense stuff but as I

mentioned it's not about completing the

entire course in one day you can use a

timeline to jump between these sections

and also with this we also have a code

there so in the description you will

find the link GitHub link where you can

access all the codes and maybe it will

help it will be helpful for you to write

this code so let's start the journey I

know you were excited to write your

first Java code but the thing is to

write the Java code you need a place to

write the code right so basically you

need a editor of course notepad works

right we all love notepad apart from

notepad we have multiple softwares using

which you can write your Java code maybe

you you can use wordpad or you can use

notepad plus plus you can use edit plus

when it comes to programming there are

multiple editor options available

specifically for Java the one of the

most famous IDE now IDE stands for

integrated development environment so

basically we have editors where you can

only type the code or you can use a IDE

where you can type the code we can where

you can run the code where you can

compile the code where you can debug the

code and you can do everything in an IDE

now which is good now for beginners

using editor makes sense but then if you

are working on a real project you can

use a IDE now it is depend upon you

which idea you want to use in this

course we are going to use vs code

now there are multiple options available

we have Eclipse IntelliJ IDEA we have

netbeans in fact I have worked on a lot

on netbeans I just start off my career I

have worked on Eclipse as well for some

few years and then I've worked on

intelligent idea of one or two project

my personal favorite is intelligent idea

the only thing is the ultimate version

which is awesome is a paid version the

community version is good but it has

some limited features

now why we are using vs code is because

it's a very lightweight editor or an IDE

so you can do everything in vs code and

it's also lightweight

okay apart from that you also need a

compiler right so of course that when

you write a code of course you have to

compile your code so that your machine

can understand that and in terms of java

we have to download jdk which stands for

Java development kit now how do you get

these two softwares it's very simple

just go to your browser and search for

jdk download and also you can search for

vs code so these are two softwares we're

going to use

let's start with JK first in jdk we have

two versions We have a propriety jdk of

what I call and we have a open source

version in fact there are multiple

implementation for open source you can

choose any of them uh we have collector

we have different implementation you can

just export them but I'm going to use

Oracle jdk here yes at one point Oracle

made a Java paid but now it's free again

so we can use Oracle jdk here and you

can just click on the Java downloads

and you can see it will give you

multiple options the thing is

at the point of this recording Java 19

already launched Java 20 is going to

release soon and with every new version

in fact Java is following this six

months uh updates now so every six

months you will get new updates right so

with every new update you will get some

features but the basic language will

remain same so irrespective if you are

watching this when we have Java 25 don't

worry Java is Backward Compatible and

the basic language features will be same

of course W minor 2x in the new updates

new features

but overall it will be same in case if

there is something new happening which

is changing the basic concept uh we are

going to re-record that video in the in

this series

okay now which one it wasn't to choose

here should we go for Java 19 or Java 17

the thing is with every six months you

get new features right but not every

version is LTS LTS stands for long term

support so there are some versions which

get long-term support now Java 17 is one

of them so instead of downloading Java

19 we are going to go for Java 17

because it's LTS

so if I click on Java 17 here

and you can depend upon which OS you are

using I'm using Windows here or for the

kojo we are going to use Mac OS but then

the setup will change but the underlying

software will remain same the code will

remain same right so irrespective of

which OS you are working will not make

any difference for for the course

but for this video I'm using Windows

here and if you're using Linux you can

choose Linux distribution or Linux

package here

if you're using Mac OS you can download

Based on is it a mac Apple chip or it is

a Intel chip

and you can go for Windows as well if

you're using Windows and for this

machine I'm using Windows so you can

click on this download here and it will

take some time for the downloading

this setup is actually very simple you

just have to change one thing which I

will show you in some time and

straightforward in Mac

uh in Windows you have to set the path

okay we'll see how to do that

next is vs code and you can just click

on this download here now first of all

vs code is a very popular IDE now if

you're coming from some of the languages

you might have already used vs code so

it's quite easy

okay now depending upon which OS you are

using you can download one I'm using

Windows here I will click on download

and yeah it's starting soon and you can

see it is downloading here

now let's start with the jdk first when

you click on jdk

uh it will take some time the thing is

in my machine I already have this two

softwares so the first screen might

might look different for both of us

you can see from it says reinstall I

will say yes so here you can see it says

next in fact for you as well you have to

just click on next next everything is

smooth and depend upon your machine

speed it will change

the speed might change

okay that's jdk install but how do you

verify if you have jdk okay we'll do

that in some time but let's do the setup

for vs code again straightforward setup

uh say I accept you don't have a choice

here you can say next next

um

nothing to specify just body fight will

be there so just keep it and install so

by the time it is happening what I will

do is I will open my command prompt and

how do you check if you have Java

installed so go just type Java

hyphen hyphen version and it will give

you the Java version if it is coming

that means Java our JK is installed in

fact you have to check one more thing

which is Java C version for the compiler

and you can see it is getting giving the

version here but in case if you get

error that the Java C command not found

even if you have installed it that means

the path is not set how do you verify

the path here

it's very simple actually or you can

just go to search and search for

environment variables or if you type

environment it will give you the first

font just click on that and here if you

can see we have an option of environment

variables just click on this environment

variables and you can see we have user

variables path here you have to make

sure that you have a path variable or

you can edit times in system variables

if you want this to be applied

throughout the system different users

then you can use system variables or you

can use a user variable here

I will go for system variable make sure

that you have path in case if you don't

have a path click on new and set the

variable name as path and set the value

now what is the value here now the value

is your bin folder so what you can do is

you can go to your C drive go to program

files search for Java here you can see

we have Java and open this jdk click on

bin now this is a path because inside

this bin you have Java C so copy this

and you can paste it here in the

environment variables value

now since I already have pathway table I

will not create new if you don't have a

path variable create click on ok but I

will not do that because I already have

a path variable just double click it

it will show all the path variables for

my machine I already have it here if I

don't have it find the empty place or

click on new

paste and you're done

and click on OK for me it's only this I

will just remove this

and click on ok ok now once you do this

setup you have to make sure that you

restart your CMD

and now try for

Java C version and it works okay so

that's how you install jdk and make it

work now let's open vs code now once

your vs code is installed

you can see it's done for me I will say

launch so that's how vs code looks like

now this is a place where you have most

of the settings in fact I have already

used vs code in my machine with

different extensions and that's why you

can see them here but for you I don't uh

you will not be having this extension

you will be having only first four uh

now how do we check if everything is

working just click on Terminal here new

terminal

and try to do Java C here as well and it

works so your jdk and vs code is all set

now you can start the code now once we

have our setup done it's time to write

our first code that's right so finally

we are going to run our first Java code

here now for that we have to open our

editor so of course in the last video we

have discussed that we are going to use

vs code so let's open vs code here so I

will say code okay so our vs code is all

set to write our first code you can see

it will give you a welcome screen when

you do it and then it will ask you the

preference do you want a light color

dark color dark high contrast or light

high contrast I would say go for dark

because it's good for development it

will launch train your eyes at least so

let's close this get started and this is

how your vs code will look like okay

simple stuff right now what we'll do is

first of all uh where you will get your

folder so you will see your folders on

the left hand side so this is where you

will get your project all the files

which you want to work with so you'll be

having that here now of course in the

upcoming tutorials we'll be using a

different IDE and I want you to get used

to different IDs when you work with so

on the left hand side we can see we have

an Explorer here and then we if you want

to search something we have it here if

you want to add some extensions which we

are going to do later uh we'll add

certain extensions to work with at this

point we don't need any extension so

just keep it blank I mean no need no

need to install anything here in my

machine I already have something on some

other accounts but on this account I

don't think so anyway and then if you

want to run and debug debug you will

find the option here now why do we run

of course we know what to why to run

right but why do we debug the

application yeah we'll see that later at

this point let's open our files of

Explorer here and this is where I want

to create my first project now how do we

create a project now project will be a

very broad term at this point what we

are going to do is we will create some

files and of course when you merge these

files and libraries you create a project

at this point we do are not working with

any external libraries at this point we

are just going for a simple files okay

hello world right so for that what we'll

do is we'll click on open folder because

all these files will be part of one

particular folder so we'll click on open

folder and it will give you certain

options where you want to save this so I

will save this in on my desktop itself

okay in fact on my desktop I want to

create one more folder so I will say

open folder again inside desktop I would

I want to create a folder here we'll say

this is I will have a short name so it's

a course create and open so you can see

we got our course folder here what I

will do is I will zoom in inside my vs

code so that you can see everything

properly and again the recommendation

would be to watch this on a bigger

screen so that you know you can actually

understand each and every line because a

mobile sometime you will be seeing a

font size and a small font okay I don't

want to welcome I don't want to see this

page every time I open my vs code so I

will just uncheck this and click on

close here and let's create our first

file and this is where your going to

write our first code right so we have

already seen how do we install jdk how

do we check the version on the terminal

can you do that in this so vs code

itself has a terminal here so you don't

have to open the external terminal of

course if you are using Windows you will

be having an option of command prompt

but let's click on Terminal here and you

can see we have an option of terminal

click on this one

okay this is where you can enter your

commands whatever commands you have the

same command will write here so we'll

say Java version and you can see I have

Java 17 in this machine and Java 18 is

already released but then Java 17 is the

LTS version so when you say LTS it means

long term support right so we'll use

that and we'll also check if my Java C

is working you can see javasa is also

there now Java C basically stands for

Java compiler as we discussed before so

we need both we need Java to run the

application we need Java C to compile

the code right okay cool so we got the

terminal as well I will just minimize

this a bit okay so now let's create our

first file so what we are going to do is

we'll click on this particular file here

and we'll name this as Hello dot Java

now this is something you have to

remember whenever you create a Java

project you have to make sure that you

give an extension or Java files

basically you have to give an extension

with DOT Java now different languages

have different extensions and when you

talk about C we say dot C when you say C

plus plus language we say dot CPP when

you say JavaScript we use dot JS in the

same way in Java we say dot Java simple

stuff right so you got our file here now

vs code will give you some suggestions

will ask you to install some extensions

for Java and we'll click on

recommendation okay it is asking us

tension pack for Java which will help us

it will give you some options and extra

stuff again this is just an advantage

which you get from vs code again not

required if you don't want to install

this extension I think I should go for

it or we also have intelli code for AI

assistance but yeah we'll stick to this

extension again in your machine you

don't have to install this there's no

compulsion you can still write your Java

code but maybe it will give you some

suggestions and stuff in between let's

see let's close this and let's write our

code so extension will be installing

behind this thing you don't have to

worry about it so basically how do we

write our Java code it's very simple

actually uh first of all the question is

what you want to do in this code do you

want to create a game or do you want to

build a rocket which will go to mass

they will not be doing those extra stuff

what I will do now is I will create a

very simple file which will print hello

world I know that's how you start a

programming language so it is

irrespective of which language you're

learning the first thing you do is you

print hello world so here I want to

print hello world now how do we do that

see uh if you in case if you are coming

from other languages let's say python

right so what you do is if you want to

print hello world in Python you can

write only one line and maybe Java is

not that famous for Simplicity at the

start of course when you build a bigger

project Java is much more structured

compared to the languages but then to

start with it's not that easy so just

bear with me okay so what we are going

to do now is if you want to just

experiment with Java if you want to play

some if you want to test some code or

stuff we have an option which was

introduced in Java 9. so basically you

can write your code in one line you can

get the output example so even before we

jump to hello world let me show you

something so so we have we have a

concept of J shell in Java so it was

introduced in Java 9 as I mentioned so

you can open your terminal and here let

me just increase the size a bit so what

I will do is I will click on J shell or

I will type J shell and it will give you

a j shell prompt okay now J in this case

is Java so you can it make it should

make sense now okay so what you can do

in Json is if you want to experiment

something example why do we write code

why do we build applications so to solve

problems right now it can be a very

simple problem as well example if you

want to add two numbers it's very simple

you can say two plus three and if I say

enter you can say we got five right so

we got the answer which is five what if

you want to do a subtraction you can do

that so 9 minus 6 and you can see we got

three so this is working but what if you

want to print something so in this case

what you can do is whenever in Java if

you want to do something we use

something called Methods at this point

you don't have to remember methods on

what the definition is just remove that

there is a concept called Methods using

which you can do something the only

thing you have to remember is if you

want to do something you need methods in

the same way if you want to do something

here I want to print something right so

we have to use a method called print it

is a inbuilt method in Java so you don't

have to worry about it just use it it

will work so whenever you call methods

you have to pass the values so I want to

say hey print but then it will say okay

I will print but what you want me to

print so you can mention that in this

blanket so in this round brackets you

can mention I want to print hello world

now if you want to just print a number

let's start with that first so let me

just print a number which is six and uh

in Java there's one more thing you have

to put a semicolon at the end it should

work in this but then remember this at

the end put a semicolon that's how you

mentioned hey something is getting ended

so we're going to semicolon there and

now what you can do is uh let's try to

run this code now adults right adults

are very important in your life in your

program in life basically you still got

there it says cannot find a simple call

point it's not working okay cool no

problem so let me just clear the screen

now clearcom is not working ignore that

you will say so let me open JSL once

again and let's because I just want to

keep it on top so what I will do now is

if I want to print something and I want

to print a value 6 at the end I want a

semicolon as well now Java says if you

want to call print print belongs to

something right so it when I say it is

available inside Java so the statement

you have to always mention is system dot

out dot println see there will be a

point where you I will talk about what

is system what is out at this point it's

very difficult to understand so just

bear with me this is a statement which

you have to re which you have to use if

you want to print something on the

console okay so if I want to print

something here just say system.out.print

and whatever value you want to pass say

enter you can say we got 6. but what if

you want to print hello world I don't

want to print six so if you want to

repeat the same statement of course you

can type or you can click on the up

Arrow it will give you the option now

here if you want to print hello world

you have to put that in double quotes so

whenever you want to do something with

text see numbers are easy to use you can

simply say six but if you want to work

with a text you have to put that in

double quotes the way I've done it here

so in this double quotes you have to

mention hello world right that's how you

start a programming programming Journey

right I will say enter and you can say

we got hello world what if I want to

print something else which is very

simple you can say double quotes not

been ready the Disco and if I say enter

you can see we got the text so whatever

you want to print just put that in

double quotes and it should work and you

can see we are getting the output as

well so cool so we are able to do this

with the help of J shell but will it

work in this if I try to copy this in

fact why to copy when we can type it so

let's type system

dot out dot print Allen and here we'll

say hello world and let's give a

semicolon at the end it was working on J

shell but when you work with Java files

because this is how you build a project

right Json is not to build projects it's

just for the experiment if you are

learning a language which is good but if

you want to make it work you can do if

you want to build a big application say

dot Java file and write your code there

so let's compile this code now how do we

compile okay so there are two steps you

have to follow first when you write a

code you have to compile the code and

then you can run the code so to compile

the code you can say Java C in the

terminal and let me just increase the

font a bit so you have to say Java C and

then you have to mention the file name

so first you have to be make sure that

you are in a correct folder which is

course you can see that this is a folder

we have and then you have to mention

Java C and then the file name the file

name in this case is hello.java click on

enter oh we got an error okay so it says

something is missing you know something

else was expected and you are giving

this is not working so this is not how

you write applications or code in Java

file we have to do something else but at

this point we have understood right how

do you work with JSL so you can if you

want to do something with JSL just write

a code it will work if you want to add

two numbers it will work you can't do

that here we have to do something extra

so let's solve this problem so we are

not able to run this code right this is

not working we want to get Hello World

on the screen it was working with J

shell because J shell says it's just a

password statement I will work but then

when you build an application when you

run the application how exactly it works

behind the scene once we understand that

we can write this code so in your

machine you will be having something

called j v m Now by default when you say

Java is platform independent is because

of jvm because in your machine you will

be having jvm irrespective of which OS

you use it can be Windows Linux based Os

or Mac or whatever famous OS we have it

will have jvm installed and of course if

you have jvm you can run Java

application and if you don't have jvm

you can't run job application okay so we

got jvm here right now what jvm says hey

I will work but then there's one

question when you say jvm will work but

jvm works on which environment so

underlying we have your OS so this is

your OSS and then your OS is working on

a hardware right so you'll be having a

hardware it can be a laptop it can be a

desktopic in your phone doesn't matter

you have a hardware on top of that we

have an OS on top of that we have

something called jvm now jvm says okay

my job is to execute a Java code okay so

whatever Java code you create JV will

execute that but then jvm will not

accept the code directly see what

happens is Java goes in multiple steps

in Java application when you as a

programmer so let's say you are a

programmer here and when you write a

code you will not directly run write a

code which will run on jvm okay and we

don't even do that right we don't even

write a code which actually works on the

hardware and we don't even know the code

which works directly on OS Java says if

you want to make it work you have to run

your code on jvm but then JV will not

understand what you are talking about

and one more one more thing we have

talked about right Java is platform

independent so what does platform

Independence means it simply means that

you can run your application on any

machine okay so when you write a Java

code it will run on any machine

irrespective of the hardware or the OS

but the only thing it requires is that

machine need to have jvm so irrespective

of which platform talking about if it

has jvm your application becomes

platform independent but jvm itself is

platform dependent okay so example you

can't run jvm on iOS so we can't say

Java is platform independent when jvm

itself is is dependent so yes your

application is independent jvm is not so

jvm need to be built for a particular OS

and let's say if it is Windows in my

it's so in my machine it is Mac but

let's say if it is Windows we have jvm

available on Windows so your jvm says

hey I will run your code but you have to

submit me not the Java code but

something called a byte code so you have

to convert your code into a unreadable

format for the normal human bin and this

is called a byte code

because jvm only understands byte code

but can you write byte code of course

not you only understands English type of

languages right so whatever we have

returned the code we have a

returnsystem.out.print it's English like

language right so what you create is a

Java code so this is your Java file or

Java code and then you have to convert

this Java code so this is Java code

which is mode of readable this is not

something which you can read so

basically you have to convert this into

a Java code or byte code so for that we

have something in between here which is

called a compiler now since this is a

Java compiler we can call it as Java C

which is Java compiler okay so basically

you will write this code so this code

will be getting compiled into a byte

code and that byte code goes on the jvm

it will run okay makes sense right so

that means when you write something it

will go into byte code and then byte

code will run on jvm now the only thing

is see your project can be a big project

right here I'm writing only one file it

can be 10 lines of code it can it can be

10 files it can be 100 files it can be

thousand files out of all these files

there will be only one file with jvm

Will execute okay JV will start with the

first file and then of course that file

will depend upon the files and it will

execute so jvm says you need to tell me

what that file is okay so if you even if

you have thousand files which you want

to run in your project you have to give

the first file so in this case what you

will do is you will specify hey that's

my first file so when you run the code

you will specify the first file and also

that file need to have something called

a main method okay so as I mentioned

before right we have print in the same

way we have main so your file the first

file need to have a main method so when

I say first file it is not like you have

to follow a sequence create this file

then that's that file out of all the

files in your project the execution will

start from the first file which you

specify okay and that file need to have

main not just main it is looking for a

specific signature okay so when is the

signature it means the entire method

signature the method name what are the

values you're passing and all the stuff

and of course all this term you will you

will get used to in some of these

sessions don't worry so first you have

to make sure that you provide a main and

Main has a particular signature again

what each word means that we'll see

later so the signature is this it is

public static void main so you have to

remember always pass this method I know

there are four words but then this is

the thing you have to remember and Main

will accept some arguments some

parameters so you have to pass string a

now again we'll discuss this what this

string is what is public static void

we'll discuss that in some time but main

is looking for the signature so your

code will not work without the signature

okay so remember this so that makes

sense so what are the steps you have to

follow so the first step is as a

programmer you will be creating a Java

file okay now once your Java is ready

you will put that into compiler then

compiler will compile it then that code

becomes a byte file a byte code

basically then you will take this byte

code you will run that on jvm now once

you once your jvm says okay I'm running

the code jvm will look for this vertical

syntax it should be there in your code

and then you will get the output right

simple stuff okay now there's a space in

between here if you can see this is a

space I have left left that space

intentionally because we'll add certain

things there so at this point just

remember there's a space here there's a

box remaining here we'll we'll add that

box in in some time now once we have

understood all those things it's time to

expand this code now if you remember we

have to write everything in a main right

so this section should be a part

of remember what jvm will ask you for JV

will ask you for main so we have to put

that into main so what your Syntax for

main it's very simple it is public

static void main we have seen that of

course this words will Define that words

in the upcoming session and once you

understand all these terms you are Java

programmer right and in this will say

string a and that's it this is a syntax

to follow now there is one more thing uh

in Java now Java is object oriented now

what is object oriented means we'll

discuss that later but in simple terms

object oriented means everything should

be an object and to create object we

need to class okay again we'll discuss

all those things in the upcoming session

but a class is missing here in fact if

you compile this code this is what your

Java say will tell you JavaScript says

hey where is your class your class is

missing okay let's do that so let's put

that a class here and we'll give a class

name at this point we'll keep the class

name and file them same and we'll say

Open Bracket and close and we'll give

our indentation so basically we have to

follow this thing always give a tab so

every time you open a curly bag give a

tab it looks good okay there's no

compulsion it looks good and we love to

build stuff which also runs and looks

good okay this looks good right ignore

this accent these suggestions uh these

are the exercises coming from your vs

code but you know that part in fact is

it because it's happening of this

extension let me just remove this so

let's not use that extension because it

will give you a suggestion it's good for

development but not for teaching purpose

so it adds extra text there okay cool so

this is how you write your code okay we

got a class a file name and then public

static void Main in bracket you have to

mention the parameters again we'll

discuss that later and the only thing

important statement here is

system.out.print Hello World okay now

let's see if this works let's create the

screen and compile you can see there is

no error but the moment I compiled if

you can see on the left hand side we got

this extra file we got hello.class now

this is your byte code remember we have

talked about a byte code here this is a

file which got created automatically so

when you create a Java file when you

send it for the compilation it will

create the byte code and the extension

for the byte code is Dot class file the

extension for Java code is dot Java file

and now it is compiled done right now

it's time to run your code so remember

when I mentioned to run you have to use

jvm and for that you have to use a

command which is Java and you have to

mention the class name not a file name

this time just a class name the class

name is hello and say enter you can say

we got hello world so yeah that's how it

that's how it works so simple stuff

that's why we can able to complete our

code and we are able to run this code

now if you have done till now give a

round of applause or a part on your back

because you deserve it okay so this

makes sense right so there's a gap here

right so let's remove this Gap so what

we have here so basically you know when

you when you run your code basically

think about you're cooking something in

a kitchen right so where do you cook of

course in a kitchen right why not in a

hall or in a bedroom it's because in the

kitchen to cook something you need extra

things right example if you make a

Biryani I don't know if you know the

recipe even I don't know the recipe but

if you make a Biryani you have to add

extra ingredients right now those things

are kept in the shelf so in the kitchen

you will not just have that resources

which are there in the platform but also

you'll be having extra stuff now the

same way if you want to run your Java

application you need extra libraries and

you also need a runtime now runtime is

something which where you can run things

right now you can run something in a jvm

so that is part of run but then what if

you need some extra libraries you have

to Unix you need a environment as well

so Java provides you one more thing so

we have one more layer here which is

above your OS which is called JRE so

when you want to learn something you use

JRE to run it now JRE stands for Java

runtime environment and what is your jvm

jvm stands for Java virtual machine okay

so basically we have two things we have

a jvm and we have a JRE now jvm is a

part of JRE now what else you'll be

having inside your jvm you will be

having some libraries so jvm with

libraries is a part of JRE so whenever

you've done something it runs inside the

JRE and jvm is actually responsible to

run it okay and by default when you when

you want to run your application on any

platform it need to have JRE which will

have jvm now not every machine will have

Java C Java C is only for development

purpose right so we can imagine this in

this section uh so basically we have an

outer box which is your jdk which is

used by developers inside which you will

be having something called JRE and in

this you'll be having jvm so as a

developer you'll be installing jdk jdk

will have JD Jr you will have jvm but to

run something on any other machine let's

say if you have met the application you

want to run this on your friends machine

your friends machine will only have JRE

and jvm jdk is not required and that's

why we say Java is Vora which is write

once and run anywhere right so you just

write on your machine you can run it on

any other machine provided you have jrd

and jvm installed so that's how your

Java behind the scene I hope it makes

sense now okay so we were able to run

this code and we understood something

what is happening behind the scene right

so basically we know now that as a

programmer as a as a Java developer you

write our Java code which will be having

dot Java extension and that gets

compiled by Java C and then when you

when you compile the code what you get

in output is a byte code which will be

having dot class file and then you can

run the dot class file in your JV I mean

basically it's a part of JRE which will

have jvm as well as a libraries lot of

classes and then everything is a part of

a JRE that JRE you will be installing on

OS right so basically you need to have a

hardware of course you need a machine to

run right that machine will be having an

OS and then OS will be having JRE which

is which will have jvm but as a

developer you will need one more tool

which is jdk now when you install a new

jdk you get the updated JRE and jvm with

it okay so the version of jdk which we

are using is is 17 which is LTS which is

long-term support and in every new

version you get some minor extra

features right so even if you are

watching this after 10 years or 80 years

or five years you will be having new

version of java of course next five

years you will get 10 new versions and

every new version will have minor

updates but the base Thing Remains same

right so whatever you're learning is

actually from java one itself the

system.pinterland is same in Java one so

don't worry about the new updates the

code concept will remain same okay cool

now once you have this thing what next

we can do now think about this world of

course first of all why we build

software we build software so that we

can solve a problem now what problem we

are trying to solve uh so basically we

are trying to solve the real world

problems uh with the help of virtual

world example you wanted to buy

something so you've got Amazon which

delivers everything at home so you got

Amazon is online service you want to to

book a cab you got Uber so for every

problem we have a solution in the

virtual world right so banking

everything is happening online now when

you say you are replacing the real world

with a virtual world solution so

basically we need to work with one thing

the most important thing now is actually

data so basically we want to work with

data so how will you work with data so

basically you need data as well as

processing on it so whatever whenever we

build a project or when you build

application what we are doing is we are

doing the processing on data now this

data can be coming from user or

something so maybe you will accept the

data from the user and then you will do

some work with it maybe you want to

store this data now where exactly do we

store data so we store data in something

called database so we have a database

here in which you will be storing your

data so whatever data you're getting

from the user or from after processing

so let's say we got a user here user

sends us data we will apply a processing

on that so we will do some work in

between and then then at the end we

might store data in database now this

database is actually a permanent storage

or a persistent storage which you say

now when you say it is permanent that

doesn't mean you can't change it of

course you can you can replace the

values as well but then the data stays

there okay so if you just store it and

if even if you shut down your machine

the data will be stored example when you

copy movies or games on your laptop it

stays there right it will get deleted

when you say delete but the data stays

there so this makes sense right but when

I say you will receive data from the

user and then you will be doing some

processing on that where you will store

the data for temporary purpose of course

database is there for permanent storage

but during processing you have to store

your data somewhere and that somewhere

is variable so this is where you store

your data now what is variable so

imagine variable as a box and in this

box you will store your data now what

data you want to store your data can be

numeric it can be text it can be image

whatever you want to store so you can

store that data in this variable now I'm

not talking specific to Java in general

user you want to store data you will

store that in a box and that box will

have a type to it it can be of type

numbers it can be of types text or image

or video so here we are trying to store

data right so let's I want to store the

number which is five so this box will

have a number five and it will also have

a name to it maybe I can give a name

let's say a number it doesn't matter

what name you give of course there are

some restrictions on names but num works

you can use any name which you like

maybe you can create one more box here

and you want to store the number itself

but let's say a decimal value something

like 6.5 you can do that okay and maybe

you can have a different value to a

different name to it maybe you can say

marks or grades or maybe you want to

have one more box where you want to

store your name so I can do that I can

store my name as Naveen and it will have

a variable name so maybe I can say this

is user so user is Naveen so basically

what you do is you create a box and

inside the inside the Box will be having

values now this box are actually called

variables so we can name this box as a

variable okay and so what we got till

now we got thought that a box will be

called a variable and you will be having

a name to it you will be having a value

so name and value will be there apart

from that you know Java is actually

called strongly typed language now what

it means is whatever variable you want

to create so if you want to store the

data of course Java says hey we'll

accept the data but tell tell me also

what kind of box you want a different

type of data will require different

blocks okay that makes sense so I will

say hey Java I want to store a number so

I want to create a box for me which will

accept numbers so we can say okay this

makes sense number will go there we can

also tweet this as a number but this is

a text right so in Java we call them as

a string right so text will be having a

string so this box type is string what

about this box of course we say this is

number this is also a number but in

number as well we have a category inside

it so one of the categories I will

mention is this we can if you want to

store numbers we can store that in

something called in now int means

integer okay so we can store data in the

integer format but we cannot store 6.5

in it because 6.5 is a real number so

int will accept numbers but white is

called int why not natural numbers or

whole numbers is because maybe you want

to store negative values as well so

remember your maths concept so we have

negative numbers to positive values so

everything will be considered as int so

we can store minus 5 plus 5 that's your

choice okay so this makes sense what I

will do now is if I go back to the code

of course we want to print hello world

but we have done that now I want to

store value so that I can do some

processing on it now what kind of person

think I want to do maybe I can I want to

add two numbers maybe two plus two or

five plus six simple stuff right but

before that we'll see how do we store

data even if you don't store data you

can just go inside this system.print

whatever option you want to perform you

want to say three plus five that will

work so you can just go back here and

say compile and run so remember this

thing every time you make a change just

make sure that you compile it first so

the first step is comparison and then

running and you can see we got the

output 8 just ignore this percentage

symbol as of now I'll show this one more

thing I wanted to mention whenever you

print something let's say I want to

print this number here as well I want to

perform different options so you can

write multiple statements for different

operation you want to perform so you can

say eight plus seven so we are doing

addition here and the addition here

let's clear the screen okay I have to

first compile okay that's what compile

run and you can see we got the value

now the only thing you can see is the

result are bit that together right we

want to give a space of maybe I can

train 15 on new line so what you can do

is instead of using print you can

actually use something called print Ln

now print Ln means print new line so it

will print and it will go on new lines

so we can do that here as well so just

say Ln Ln at the End Print Ln which is

print new line and now compile run and

you can see we got the value we got 5

and 15. so from now we'll not be using

print we'll be using Ln println okay so

again println means it will print it

will go on new line so we got print Ln

now what else we can do here so I don't

want to perform the operation here

remove that I want to store that value

first so how do we store it of course we

need box right so I can say num1 I can

as I mentioned I can use any variable

name so let's say num1 or to start with

let's say num just to keep it simple and

then we can give a value to it let's say

value is three so remember you have to

mention the variable name and then we

have to mention the value for it and at

the end of course you can put a

semicolon so we can see we got num equal

to 3 and we got semicolon so in Java

after every statement you have to give a

semicolon you might be thinking hey why

don't we have a semicolon here it's

because that is a block so we don't put

a semicolon out at the end of a block

the reason is it signifies that's the

end here if you don't mention semicolon

how do we Define that that's the angle

so it's good to put semicolon at the end

and anyway Java will give you either if

you don't do that the next thing you

have to do here is we have to also

mention the type what type of num is

this so we can say int now we have to

say first you have to specify the type

and then you mention the variable name

maybe if you have learned some other

languages where you put the type

afterwards in Java we first put the

value or put the type and then we put

the name then we Ascend the value now

this equal to here is called assignment

operator because you are assigning a

value so what it will do is it will take

the value from the right hand side it

will assign the budget to the left hand

side okay remember this equal to will

take the value from the right hand side

it will assign the value the left hand

side okay so we got a variable which is

of type int okay so this is num which is

a variable and then we can print it now

let's only print the value that's it

nothing much I will say save now once

you click on save you have to compile

the code

and run the code and you can see we got

three Okay cool so now can I create more

variables we can actually so let me just

rename the value variable from num to

num1 and here as well I will print num1

okay and then I will create one more

variable which is num2 is equal to so

every time you want to get a variable

just mention the type which is int or

whatever type of variable you're

creating at this point we are working

with numbers so we'll say end num2 equal

to we're going to assign the value which

is 5 so we got 3 and 5 here what you can

do is you can actually perform the

operation here itself so against the

num1 plus num2 that works so instead of

adding values we can also add the

variables okay so now we are what we're

doing is we are saying num1 plus num2

and the addition will be getting printed

let's try so I can just go back here and

say compile run and you can see we got

eight you know what instead of adding it

inside this it's not a good practice

what you can do is we can create another

variable called result and that's right

variables are free to use of course

behind this engine is consuming a lot of

memory

but it's working right it's free as of

now but later on we'll focus on how can

you make your code more efficient so

that it will use less space right at

this point it works so we can say now

one plus so whatever option you want to

perform you can do that here and instead

of printing and this is doing addition

here we can simply print result so what

you're doing now is you're adding the

value and then you are storing that in a

result and then you are printing it it

should work let's try compile run and

you can see we got eight so this is

working so that's how you can you can

create variables so remember this thing

every time you want to create a variable

you have to you first need a name for it

at this point is num1 you have to also

mention the type of it at this point

this is int and you have to assign the

value for it in the upcoming videos

we'll talk about how can you create a

variable which will be having a name

with a different type and different

value so now we know what variables are

and how do we create them so basically

in the last video we have talked about

how to create a variable with the help

of the data type and the value as well

now what are the other options we have

so we have worked with eight right do we

have other options so basically we have

multiple data types to store your data

so let's talk about the first thing

which is uh data type in fact there are

two categories of data type which we can

normally work with one is called

primitive and the other one will be will

keep it question mark okay at this point

we are not just discussing about the

second one the first one is primitive so

basically in Java we have lot of inbuilt

data types available which you can use

and they are primitive now primitive

simply means it is simple basic to use

to work with so what about data you

normally have normally we work with

numbers we work with Point values we

work with characters we work with true

or false now for that we have this that

category so we can divide primitive into

four categories here uh the first way

one the first one is of type integers uh

the second one we have is float floating

point value basically so we can say

float and the third one is characters

and the fourth one is your bullion of

course when you divide this we have more

categories to it but in general we have

four we have integer float character and

Boolean now when you say you want to

store a range a negative range to

positive range numbers normal numbers or

natural numbers you can say in fact we

can we can call them as integer itself

because we are starting with a negative

value so that goes into integer whenever

you have Point values which that goes

into float value whenever you go with

characters like a b or any Regional

characters you have all across the world

that goes into character and then when

it comes to true and false we go with

Boolean now inside integer itself we

have multiple subtypes to it uh we have

a concept of byte we have short we have

int and we have long uh for float we

have another option which is of double

and of course we have float and then

carries characters are characters so in

characters we can have different type of

characters in Boolean uh the only values

we can have is true and false okay uh so

example if I go back to my code and if I

want to create a different video table

this time let's say float so I can just

come back here I can remove this section

and here I can say this we are creating

a float value now how do we get a float

value base so we can simply say float

and then we can have a value let's say

seven or we would name to it right so

name we can have is marks of course we

don't put in marks but let's go with

marks and then we can go with a value

now floating Point values would be

having a DOT right so we can say 6.5

something like this uh some float marks

equal to 6.5 that makes sense right okay

cool in the same way we have also

mentioned we have subtypes to integer we

can have a byte format but why do we

need all these extra formats for that

let's understand uh some basic concept

now basically when you talk about

integers itself so if you talk about

integer we have some sections to it so

integer will have different part so

interesting will have different sizes

example if you want to store a normal

number so in general we always go with

int and int has its own value okay so

when you talk about in the size of int

is is four bytes so we can say 32 bits

and then it has a range to it and you

can find the range on the screen uh we

also have a format which is let's say if

you want to store a bigger value a very

big value so in this case I'm I mean of

course the value goes beyond that range

we have to go for the long format now

long supports eight bytes now of course

when you have more budget it will occupy

more values and it will have a range so

of course you can find the range on the

screen now what if you want to store a

smaller number so of course int provides

you that range but then what if you want

to save memory you don't want to go for

end range in that case we can have a

short value now short is only two bytes

so if you want to have a limited range

you can find the range on the screen and

then we have the next range which is of

byte now byte is only one byte okay so

eight bits and whatever you want to

store you can store in that of course it

has its own range now how do we

calculate this range so we do with the

help of it goes from negative values

right so it is minus two raised to 8 2

plus 2 raised to eight minus one okay so

which is 2 s to 8 is what it is okay

starting with negative value right so

just two is to 7 and 2 is to 7 and the

range so how do we calculate version 7

is 128 so it starts from minus 128 to

plus 127 so 128 minus 1 127 that's how

you can calculate the range for all the

other numbers and you can of course you

have seen that on the screen so this is

how we can use integer so which one to

use so if you want to get a variable

which is a which will have a value let's

say five or six or maximum 127 you can

go for byte now how do you get that

variable it's very simple you use a type

which is byte you specify a variable

name let's say num and you assign a

value which is eight or any other value

which you want of course that should be

in a Range and that's how you can store

it now what if you want to have a float

value now float actually gives you two

different values or two different types

now it depends upon which programming

language you have worked with before

example if you have ever worked with CVA

by default we have a value which is

float so by default we have float there

now float only takes four bytes and it

has its own values you can store and

then we also have option of double which

takes eight bytes now what you think

which will be default value think about

it will it be float or double by default

in Java so default is actually double

not float okay now why double is because

see float are good when you have limited

values when you have limited Precision

because after your point value example

if you have value which is

126.5678 or whatever values you have so

float will have a limited Precision set

here but on the other hand double will

have a longer one right so double can

have more values so whenever you perform

scientific calculations or any kind of

calculation if you wanted to make it

fast and it should support maximum

Precision you can use double there right

and by default Java supports double so

if you want to create a variable which

is with double so you can simply say

double and you can create a variable

name num is equal to you can assign a

value which is 5.6 so whatever value you

want to assign but how about float now

if you try that with float it will it

may not work example if you say float

and if you say a variable name which is

num and equal to so when you try to

assign 5.6 it will give you error it's

because by default the moment you say

Point values it will be considered as as

double and if you want to say hey I

don't want to work with double I want to

work with float so explicitly you have

to mention hey okay this is actually

double value so you can this is actually

a float value so you can put a f there

right so 5.6 F that's how you define

it's a float value for double you don't

have to mention that now how about

character so when you when you work with

character and in other languages

character will have a less bits but in

Java it goes for two bytes so so in

other languages like C you have only one

byte it's because it normally occupies

the integer range it normally occupies

the character range ASCII values but

then in Java we thought hey can we just

have all the characters in the world not

just English all the languages so Java

actually follows something called

Unicode not ASCII by default it will

support Unicode and it has two bytes

which is 16 bits so it has a bigger

range right so this is a range it

normally works with so of course you can

work with any type of values you have

and any type of characters basically you

have and if you want to define a

character variable it's very simple you

say Cad and then you specify the

variable name let's say character or c

equal to whatever character you want to

assign let's say I want to assign a

character which is K now in this K in

this case if you want to work with a

character can we use double Quotes no

double quotes is for string right for

character we have to use single quote

and you have to put your character to

single quote and remember it will only

accept a single character and next we

have of type Boolean so if you want to

work with Boolean Napoleon will only

accept true or false okay no other

there's no subtypes here only true or

false now one thing you have to remember

now in other languages it may represent

it with the help of one and zero in Java

we don't do that so in Java it does not

it doesn't work with zero and one it is

true and false this Knight like true is

one and false is zero it's only true and

false it is normally used for conditions

if you want to check for the condition

based on that you will do something

that's what we can use two and false I

mean think about computers when you say

computer can think it's because of this

true or false okay and how do we Define

a Boolean variable so it's very simple

you use a keyword called Bull and then

you mention a variable name let's say B

is equal to you either assign true or

false okay you don't have to put a semi

a single quota double quote because they

are itself keywords so these are the

options we have now if you want to see

this in a code it's very simple you can

just go back here and say okay byte is

done let's create some variables with

different type so ain't we have already

seen so it's a number one this is how

you assign integer value what if you

want to go with a byte so you can say

byte B I will say b y equal to now can I

assign a value which is 129 you can say

it will give you if I do that if I go

back to my compiler compile you can see

it will give you error it says possible

lossy conversion from into byte so this

is int which is 129 it will if you try

to save that in a byte it will not work

but what if you say 127 that's the last

value you can store compile okay this is

a problem with result let me just remove

this section and compile no issue okay

so this is how you save byte value what

if you want to store shots you can say

short sh equal to

and you can assign value which is let's

say five five eight any even number

doesn't matter and then what if you want

to work with long so long L is equal to

now when you work with long remember

this thing after every number for long

you have to put a l at the end to

specify that's a long number the thing

we have done with float we have to put F

in the same way long needs l

and what if you can do here with float

so you can say float f is equal to

5.8 okay let's try with 5.8 and let's

see what happens if you try to compile

this compile okay you can see it is

giving you it says again possible logic

conversion from double to float because

by default 5.8 is double if you want to

mention hey that's not double that's

float you can put a f at the end that

should work you can work with double as

well Double D is equal to 5.8 same value

but this time it is double and then what

else we can work with we can work with

character as well so we can say care C

is equal to in single code you can

mention the character k then we can go

for Boolean which is Boolean in this

case and you can say B is equal to True

simple stuff right uh let's try to

compile this of course we are not

printing anything so we don't expect

anything on the console compile or

there's an error it says cannot find

symbol bull okay my bad it is Boolean

the only problem is when you work with

multiple language at the same time you

get confused somewhere so that that's

Boolean notable so in the notes as well

I need to change it so I will say this

is Boolean

cool and now let's compile this once

again compile okay there's no problem

and let's run this of course it will run

but then you will not see any output

right no output because we're not

printing anything so yeah that's about

this we have different type of

data types we can work with and all

these are inbuilt apart from this we

also we also have some more data types

which we'll see later they are not type

of primitive but this is primitive data

types and this is working okay awesome

so now we know what what variables are

what data types are what a size or range

of each data type here and you don't

have to buy hard them you will get used

to it the more practice you do with this

variables you will get used to when to

use what but what if I remove that

single code there let's try compile and

you can see we got another we can't even

put double quotes there it will give you

as well and you can see you can't even

put double code so you have to put

single code because that's how that's

what character represents and the

character can be numbered as well so you

can put a character here which is eight

which is the character itself right

digital also character no other

okay so when you talk about data types

and then values what kind of values we

can have so example if you talk about

this 9 or this eight these things are

actually called laterals

because they're literally the values

right so what we can do is we can play

with some literals here let's work with

integers first and we'll come back to

this so we are basically working with

literals now okay now what kind of

relatives we can have for example we can

have direct values we have nine here and

we can have any big value provided that

goes into the range so whatever range we

have it is a part of the range it will

work so we have all these are decimal

values right so it will have a base 10

what if you want to work with base two

something like a binary format can we do

this let's try it so I will say 0b 1 0

1. so basically if you want to put a

binary number like 101 which is five so

you can put B and then you can put a

zero let me just drive this works I will

say system dot dot println and then let

me print num1 let's see if this works

put your semicolon at the end

compile there is no issue so let's run

this code and let's see what's the

output and you can see we got five so

yeah that's the binary format Works what

if you want to work with hexadecimal

numbers in this case you can use x here

and let's put a number seven e so e also

supported right so let me just try

compile run and you can see we've got

126 I don't know if that's the correct

answer but you can verify there's one

more thing which will introduce later in

Java which is what if you have let's say

this number and trust me I always get

confused with number of zeros in any

amount even if I mention a password or a

pin or account number and whenever you

have multiple zeros I always get

confused so how do you count to the

number of zeros here of course you can

do it one by one but in Java we got this

feature where you can put a underscore

between numbers if you want to

differentiate them it was easy to count

right so you can see we are getting

zeros and then we got underscore even

this works let's try it out compiled one

and you can see we got the output of

course in the output it will give you a

normal number but as a programmer it

helps you for the number of zeros you

are entering that so these are basically

individuals right let's try with float

this time so let's say this float and we

are saying num1 and then I want to

assign a very different value can I

assign let's not let's go with double

just so that I can avoid that F at the

end and here I want to assign let's say

56. so basically when you try to assign

a integer value to float it will work or

double it will work because integer will

get converted into double automatically

when you save it okay uh okay that makes

sense can I have different value let's

say I want to store a very big number so

I can actually use Epsilon e in between

I can say 10 e 12 e raised to 10 and

let's see if that works compile run and

you can see we got the value as well

here and it will adjust automatically

based on its own implementation so it is

assigning 1 0 here so there's basically

12 into 10 raised to 10 or 12 into 10

into 10 to 10 and then it will I just

it's according to its own way and we

have one we have already discussed about

the Boolean it is only true and false

there is no one and zero there uh don't

try to assign

one it will give you error let's try

compile okay you can see we got there it

says int cannot be converted to Boolean

remove this okay how about character

let's try uh so when I say character

let's just see and I want to assign a

character here which is uh say in single

code let's say a now when you try to

print the character uh this will work

compile and run you can see we got a now

basically character can be also treated

as integer that's right we can actually

perform operations I can say C is equal

to C plus one so what I'm doing is I'm

incrementing C I'm enhancing the value

of it if it is a normal value value it's

a 5 it will become six okay what if you

want to do an increment of course we'll

discuss this later what increment means

but you can say plus plus to increment

the value and if you try that with

character compile it you can see that it

is getting compiled and if I try to run

this code we got a or because we are

printing it there my bad I will just

have to put that here so first we have

to increment the value then we can print

it so C plus plus implements changing

the value okay it's not a language I'm

talking about the operation on a c

variable and you can see we got B so

when you increment the value of a it

becomes C it becomes B cool so basically

all these things are called literals in

fact there's a concept of string

literals as well where you example when

you talked about hello world that's a

string that's string literal in this

video we'll talk about type conversion

and type casting so in the previous

video we have talked about variables how

to create a variable and then one thing

is for sure in fact two things every

variable needs a name so we have talked

about it and every variable needs a type

as well so if you want to get a variable

for numbers you will say ain't float

double or long in fact we have sub tabs

as as well for INT and then if you want

to store a character we can use care if

you want to store a Boolean value we

have Boolean option and then we also

have a string which we'll talk about

that later at this point we have a lot

of different types now there is one

confusion what if you want to change the

type of a variable can we really do that

so so unfortunately we can't we can't

change the type of a variable but then

can you assign a value to other type

example let's say we have a variable

which is of type byte so I'm using a

byte variable which is B and it will

have a value now of course we have

talked about the range of byte as well

you can have maximum 127 plus I mean

plus 2 127 this is the max value you can

accommodate here but can you assign a

integer value that's a question so what

if you have a variable of type int a and

the value of a is 256. now what will

happen if you try to assign this a value

which is 256 into B something like this

what if I say B is equal to a so what

I'm doing now is I'm assigning a value

of integer to byte now unfortunately

this will not work but what will work

the reverse will work what if you have a

variable which is a and then you are

trying to assign a value which is B this

will work so what happens is the type of

a is integer right it has a bigger range

and byte has a small range so the

compiler says hey you're trying to

assign a integer value to byte and at

this point you will lose you might lose

some data so basically we are trying to

convert it and it is narrowing it right

so we are narrowing the size of it on

the other hand if you talk about this

operation here we are widening it

because this the range of byte is small

and integer is a bigger one so of course

you can put a small items in a bigger

box but if you put a bigger item in a

small box it will not work right okay

cool so that makes sense right but then

what if you really want to do it you

want to convert a integer value into

byte see at this point if the value of a

is not 256 what if the value of a is

let's say 12. now the value of a is 12

which can be accommodated in b as well

so at this point even your compiler will

say hey I don't know what your value of

a is but I will not allow you to store

the value of a in B because a is integer

and B is byte so in this case you can

say hey compiler give me one second here

what you can do is you can say B is

equal to you can convert a you can do a

conversion by saying you can give a

bracket and you can mention the type in

which type you want to convert you can

say byte and you can mention the

variable name a so what you're doing is

you're converting integer value into the

byte format okay now this constant is

called casting so basically this is

actually a conversion but explicitly

you're doing it so whenever you do

explicit conversion it is called casting

so when I say explicit there should be

implicit as well right and that is

correct we have some conversions which

are implicit example if you talk about

this particular operation here this is a

implicit conversion basically you are

trying to store a byte value into a

integer variable so it becomes integer

when you assign it right so this is a

conversion okay so when you do it

explicitly that is casting when you're

disopening if it is happening

automatically that is conversion now

this makes sense right now is it means

you can do it with anything not exactly

there are certain types example you

can't store a character value into a

Boolean value okay because Boolean only

supposed to end false and character

supports all the characters so you can't

do those conversions but anything in the

range of integer float double actually

works example uh we have talked about

integer and byte if it is long as well

that completely works now what if you

have a scenario where you want to store

maybe of type a float value now let's

say you have an integer variable here

which is int let's say x is equal to and

you're trying to assign a float value

now float value is let's say 5.6 of

course I can create a float variable I

can assign this value to that or maybe

this is double because we don't have F

so let's say this this is double and

then you're trying to assign that to

integer now what will happen is in this

case if even this will not work so what

you have to do is you have to apply you

have to convert it so what I will do now

is let me just create a float variable

here so I will say float f is equal to

5.6 and remember you have to put F at

the end now if you try to put f it will

not work so what you will do is you have

to explicitly convert this value into

integer so what you're doing is you're

assigning a float value to an integer so

you're converting it now what you will

lose here so at this point you will lose

your point values so whatever value you

have in after that point you will lose

an example the value of five point which

is 5.6 so here when you convert that it

becomes 5 so in the X the value you will

be getting is only five cool uh so it

makes sense right so for float it will

cut the value but coming back to byte

now what will happen when you talk about

byte here what do you think we don't

have Point values so if you have a

bigger number example let's say this is

not one this is not 12 let's say we have

a bigger number here and the bigger

number is let's say

257. now what will happen when you

assign 257 because the range ends at 127

you can't go beyond that right so in

this case it will use a concept of

modulus okay or modular operator so what

modular will do is it will divide this

number so whenever I try to assign a

integer value to byte which which we are

doing here so when you are trying to

assign a integer value to a byte it will

convert that into modulo which is it

will divide the number a which is 257

and it will find the percentage okay so

257 percentage which is a modular symbol

and it will divide it with a range okay

which is 2 256. because a complete range

of byte is 256 right from minus 128 to

plus 127 and then the remainder you will

get here is one cool so the answer here

when you try to do it with the 257 it

will be one I will show you that in the

code so coming back to the code let's

try all this operation which we talked

about so what we'll do is we'll start

with a integer value we can say or maybe

we can start with byte so we can say

byte B is equal to and maximum you can

have is 127 let's take that value and

let's try to print it here so we can say

system Dot dot out Dot println and here

let's print the value of B so when you

save that and when you go back here when

you try to run this so we say Java C and

Hello dot Java comparison done let's run

this code I can say Java space I have to

run with the class file which is hello

and you can see we got 127. now what

will happen if you try to do that with

257 it will not work first of all it

will say either you can see we got data

it says incompatible types because it is

integer type now 257 okay so you can say

127 here now next what I'm going to do

is I want to create a integer variable

here which is int int n is equal to and

I can assign a value maybe let's say a

because we have used that so we'll say a

and then the value we are going to

assign is of B so can you assign a byte

value to integer because this is this is

where you're doing converting and if you

try to print the value of a let's try

that in fact there's one more thing

which is which came recently in Java so

basically you know we always do two

steps right first you compile the code

and then you run the code right so you

compile that with the help of java C and

when you compile it you see you say

hello.java and when you run it you say

simply say Java and hello you have to do

two steps right so when you're into

learning phase why to do two steps you

can actually do a single step again not

recommend it for a big project or not

even for a small project don't you don't

even try that in your company for

learning purpose we are doing it so

basically we got a shortcut we can say

Java space Hello dot Java directly maybe

it is getting influenced by the other

languages where you simply mention the

command and a file name no need to

mention compile and run Subway step

let's try this and you can say it works

so you can see we got 127 it is

perfectly working and just to show you

that things are happening behind the

scene uh the value is getting changed

you can see we got 125. so from now from

whenever you have single file will use

this but remember this is just a

shortcut ultimately behind the scene we

need to do this okay I mean when you

build a project first you have to

compile the code then run on the code

this is a shortcut and one more thing

this will work only in the recent

version of java I guess from java 14. if

you have an older version of java this

might not work so if it's not working in

your machine that means you have an

older version upgrade your jdk version

Okay cool so now what I will do here is

we can assign the value right but what

if you have a integer value let's say 8K

and now you are trying to assign or

maybe let's let's get a byte value byte

K is equal to a and let's comment this

section instead of saying B I want to

assign a value which is 257. now even if

you have a smaller value let's say 12

even this will not work because

ultimately the value the I mean the type

of a is integer right you can't assign a

integer to a byte format and if you run

this code you can say it will give you

error it will say incompatible types so

we got one way which is you can just

cast it with byte so we are doing a

typecasting here so when you run this

code now it will work you can say we got

12. now we got 12 because it is a in a

Range of bite what happens when you have

a bigger value which is 257 now this is

out of range right so you can come back

here run and you can see we got one as I

mentioned before it will perform a

modulus operation which is actually

finding the remainder so it will divide

this number by the byte range which is

256 it will find the remainder which is

one I hope this makes sense right so we

were able to do the byte conversion in

conversion this is working let's try

with float now so let's say we have a

float value which is f and the value of

float is 5.6 F at the end because when

you look at a float variable you have to

put at F at the end and then we can

create a integer value we can say int

let's say this time we'll go for T

doesn't matter what variable name you

use and then if you try to put F there

and if you try to print the value of T

let's see what happens you can see we

got error again the same thing it is it

says there might be loss of the value

from this conversion but then I want to

do it I want to convert that so we can

put a casting again and we can say float

here and if you try to run this code so

you're trying to convert that into

integer right what's wrong with me and

let's try now and you can see we got

five so we lost that point six there now

this concept of casting is actually very

important when you start working on the

oops concept object and the further

concept this casting will be required

there as well at this point we are doing

casting on primitive values but later on

we'll also work with objects

okay now we have talked about casting so

what is conversion so conversion is

automatic

or we can say conversion is automatic

conversion and casting is explicit

conversion so when you specify something

it is explicit cool now there's one more

concept which is type promotion so what

are what what do you mean by type

promotion so let's say we have a byte

value and the value for byte let's say b

or maybe let's say a and the value is 10

here okay and then we got a byte which

is B is equal to 20. and then when you

perform the operation maybe maybe this

should be 129 let's let's say this is

30. now when you perform an operation on

this let's say a into B now whenever you

do a into B it is what 300 right so when

you say 300 here it is going out of byte

now can you save that into integer can I

say int result

is equal to a into B now what is

happening here you're performing an

operation on buy so when you

know Java says hey we will promote you

so this value will be promoted into a

integer value okay and you can store

that into integer so this is called type

promotions let's run this and you can

see we got an error because we are

printing T here let's print the result

and run and you can see we got 300 so I

hope it makes sense what is Type

conversion and casting in this video

let's talk about operators that's right

you can perform operations on different

values in fact we have done that before

but let's expand the examples and more

operators so basically we can add two

numbers we can subtract two numbers we

can divide two numbers we can do we can

multiply two numbers and also we can

perform an operation so that you will

get a remainder of an operation okay so

when you divide a number and if you only

want a remainder we can do that as well

so let me show you those things with a

code here so what I will do now is first

of all let's create two variables and of

course we can name any variable name but

let's go with integer num1 and the value

it will have let's say seven and then

let's have one more variable here which

is let's say five uh num2 is 5 and then

I can perform some operation and I can

save that operation in a result so let's

say if you want to add two numbers we

can do that we can save the output in

result and then to perform the operation

we can use a plus operator that's right

we can actually use a plus operator to

add two numbers and then once you have

done that we can simply come back here

we can say system dot out Dot println

and here we can print the result and

just to see if it is working and as we

discussed before this is not a good way

of running a code you have to first

compile the code then run but we got a

shortcut I can simply use Java space

file name which with DOT Java say enter

and we got 12. so when you say 7 plus 5

we got 12. cool now what I will do is uh

so we can add two numbers what about

subtraction let's try that so I will say

minus symbol and run you can say we got

two so just talking so you can add two

numbers we can subtract two numbers how

about multiplication we can do that so

we can say star num1 into num2 come back

here one you can see we got 35. so 7

into 5 is 35 that work that is working

how about division uh let's try that so

the moment I said division we have to

use a slash okay so we don't have a

division in fact that's how we do right

we say underscore or something obviously

slash so yeah we got uh Slash let's try

and you can see we got one that's right

one is a question here right so when you

divide seven by five you get two things

one is a question which is one and then

you will also get a remainder now in

this case when you use slash you will

only get a quotient not a reminder

so how will you get a remainder in that

case you have to use a modulus operator

so we can use when you say percentage

symbol like this it is a modulus

operator that what it will give you is

only a remainder okay so if I run this

code you can see we got two to the

remainder here right now we can use any

complex numbers as well whatever number

you want to perform with and I would

suggest you to try certain examples so

that you will get the get used to these

operations now all this operation

actually makes sense right these are

very simple stuff to understand can we

use some other operators as well let's

try what I will do now is let me just

remove this result for time bin or maybe

I can just comment this part I also

don't need this num2 let me only focus

on the first variable which is num1 now

let's say I want to uh add this number

one by two okay so basically the value

of number is seven I want to increment

the value by 2. so what we can do is we

can say num1 is equal to so basically we

have to use num1 which is number one in

this case and we'll add a value to it

which is two and then whatever new value

you will generate after this will be

assigned to num1 okay that looks cool

right uh let's try this I will say num1

print num1 and let's run this code you

can see we got nine so this is working

so seven became nine so just walking

right now when you know that you are

adding the number by itself okay uh what

you can do is you can just use a

shortcut

now what that shortcut says is let me

just comment this section here and let's

write it fresh here so I will say now

one

see you want to increment the value of

num one by two right you want to add

Itself by two so you can say I want to

add myself

but how much value so I have to say

equal to 2. so what we are saying is we

want to increment num1 by 2. even this

should work let's try or we got an error

because I forgot the semicolon

and let me just clear this run and you

can see we got nine so this is working

cool now it's not just tradition we can

do that for any other operation maybe

you want to subtract a number by two so

we can say subtract equal to two so it

will reduce the value by two you can see

God we got five we can multiply with

some other number maybe I want to

multiply the same number with another

number and assign it so we got 56 7 into

8 to 56 we can divide as well and so you

can use slash and all the operators

which you have awesome so this is

shorthand now going back to the addition

operator and then let's say if you want

to add it by two we can simply mention

the value 2 right we can also add it by

one so in this case if you say add it by

1 the value of num1 is 7 and then you

are adding it by one you can see we got

eight now in fact there's a shortcut for

this as well what you can do is instead

of using num plus equal to 1

you can also say num1 plus plus even

this is possible let's remove the space

in between so even this is possible you

can say num1 plus plus which is

incrementing so what we are doing here

is something called increment and if

you're on this chord you can say we got

eight so this operation let me just make

it one so all these operations are

similar okay so why I'm saying similar

why not same I will discuss that in some

time but this is similar

and maybe if you have done that before

as well when we talked about characters

you know we remember C plus plus we've

done that so yeah we are incrementing it

as well now not just incrementing we can

do decrement as well so instead of

saying num plus plus we can also say num

minus minus so what we are doing now is

decrement so when you say plus plus that

is increment let me comment this part

and here I will say num minus minus now

why you have to comment this but I want

to run this so we can say num minus

minus let's run this code if say this

works and you can see we got six so

that's how you can perform this addition

subtraction multiplication division and

increment decrement in fact we have also

talked about modulus which is for

finding the remainder okay now that was

about increment decrement right we have

talked about that now instead of using

plus plus we can actually use something

called let me just write it in comment

so instead of saying num1 plus plus we

can also say plus plus num1 you know

just to simplify this example instead of

saying num1 everywhere let's say num so

that maybe you will not get you will get

confused by that one extra symbol there

which is one uh just ignore all this

operation just focus on this part which

is numb and numb also remove this also

remove this let's see if this is working

okay this is working so basically we can

also say instead of saying num plus plus

we can also say plus plus num now what's

the difference between these two even

this also work let me just try that and

show you you can see we got eight we are

incrementing the value even this will

give you eight but what's the difference

what's the difference between writing

this afterwards and writing before the

variable so basically we have a

different names to it so whenever you

perform operation after the variable it

is for increment or decrement so when

you do it post we say it is post

increment and when you do pre before the

variable it is called pre-increment okay

so when we are doing it afterwards we

say post increment when we say before it

is doing pre increment now you might be

thinking hey ultimately the value is

same right so even if you pull even if

you do this or this both will increment

the value then why we have to defend

Syntax for it why not just simply one

the answer is it behaves differently

when you try to assign a value when you

try to fetch the value let me repeat

these two operations will behave

differently when you try to fetch the

value okay let me tell you what I'm

talking about let me show you here let's

come back here and let's say I have a

different variable which is ain't and

then I'm storing that in result and what

I'm storing is num or maybe I will say

plus plus num okay now think about this

and maybe you can pause the video or

whatever you want to do just think about

the what will be the value of result

okay I will say result here to print and

maybe you have done your thinking let's

run this and you can see we got eight so

what is happening here is the initial

value of num is 7 and then you are

saying plus plus num that means you are

incrementing it that incremented value

will be assigned to result okay and then

you got result which is eight okay so

initially I've also mentioned that this

two will be incrementing so we can also

say num plus plus even this should be

doing the same thing right let's try oh

there's a Twist here so plus plus num

and num plus plus are not same I mean it

works same with their individual

statement but when you try to fetch the

value from them when they are performing

the operation they behave differently so

let's understand what is called

pre-increment and what is called post

increment so whenever we use assignment

operator with this operation what it

will do is it will check hey we have an

option which is num plus plus but that's

a post increment so first it will fetch

the value of num let me repeat it will

first fetch the value and then increment

in fact it looks like one statement but

we have two statements here right in

fact we have this statement here num one

equal to num plus one so what it will do

is it will first fetch the value of num

which is 7 in this case and then it will

increment the value of num and it will

make it eight okay but then what is

assigned result is 7 itself and then you

are printing that seven here okay but

what will happen when you say let me

just write it here so we'll say end

result is equal to plus plus num in this

case what will happen is it will first

increment and then fetch the value okay

so it will first increment itself and

then it will fetch the value and that is

what is going to result I hope this

makes sense right so this is how your

code works when you say S Plus num and

num plus plus in fact we'll do some more

operations with this once we get started

and it will make much more sense later

so in the operations we have talked

about other thematic operators till this

point so whatever operation we have done

it is for the arithmetic purpose right

addition suppression multiplication

division but what if you want to compare

two values what if you want to have

compound conditions so we are talking

about operators right so we have talked

about arithmetic operators where we can

do calculations we can add two numbers

we can subtract two numbers in fact we

have also seen how do we increment a

value and decrement right now it's time

to enhance and go towards something

called relational operators in Real

World what we do is we basically have uh

we compare We compare things right so it

can be comparing two values and if you

can check with the help of less than uh

you can check with the help of greater

than you can also compare with two

values right if they are equal or not so

we use something called equal to there

right uh what if you want to negate

something what if you want to find a

negative eight example uh if you have a

True Value maybe you want to make it

false so in that case we also have to

move from True to false right so

basically we want to implement this with

the help of operators in programming

language now specific to Java if you

talk about we have different operators

we can use less than to compare with the

help of less than or less than uh the

first value should be less than second

value if that is true of course you will

get True Value we can also check for

greater than we can also check for equal

to now the only difference is when you

talk about equal to in programming

specifically for Java equal to means

assignment operator example let's say if

you have a value which is 5 and you want

to assign that to a particular variable

let's say x so you say x equal to 5. so

this equal to symbol here actually

becomes your assignment operator but

what we want here is we want to compare

two values right so that's why we use

double equal to so in programming in

Java we use double equal to come to

compare two values what if you want to

check if two values are not equal in

that case we can say

exclamation and equal to okay that's

that's what you say it is not equal to

so this is comparing for equal and this

is comparing for not equal and this is

of course less than this is greater than

and you can also combine example if you

remember in mathematics we use the

symbol Which is less than equal to in

the same way of course we don't have

this key on the keyboard so we have to

use less than uh

so we have to use less than equal to for

this particular combination uh we can

also say greater than equal to right so

we can use all this combination which

comes up as a part of a relational

operator now basically when you compare

this to what your example let's say if I

want to compare if 7 is less than 5 so

this will return u a value which is true

or false so it will be either true or

false of course we got a static value

here which is seven and five so the

output for this will be of course false

but if you say 5 is less than 6 yes

that's true so that's how you define uh

that's how you compare two values and

that's how you get the output the point

to remember here is the output which

you're going to receive is a Boolean

value okay now how do we Implement that

in a code so let's go for that so let's

say uh we have this our we have our code

here and in this what I'm going to do is

I have two values let's say integer I

can say x equal to 6 and then I got Y is

equal to 5 and now I want to compare

these two values the way you can do that

is of course when you compare these two

values you will get a Boolean value so I

can say Boolean uh against the result is

equal to now how do you store a value

and how do you compare so first of all

storing is easy you can just assign the

value but how will you compare in that

case you can say x is less than y and of

course that's available on keyboard so

you can directly use it

and what I want to do is I just want to

print uh the output here

so I can say system Dot

out dot println just for printing stuff

and then I can just say result now the

moment you say result it will print the

output and of course you have to compile

this code and the way you can do that is

by saying Java C

demo.java enter okay there's no issue

with the compiling because the syntax

looks good and now I will just run this

I will say Java demo enter and you can

you can see we got false now why we got

false is because the value for x is 6

and the value for y is 5. so the first

value is lessons is not less than second

value and that's why we got false

greater than simple here it actually

makes sense because that's a

oh remember every time you make a change

first you have to compile the code and

then you can run the code and you can

see we got through this time so

basically that's how you can compare two

values and you can print it but what if

these two values are equal so let's say

we got 6 and 6 and now if we try to run

this code of course compile and run we

you can see we got false

okay but then they are equal right so

maybe I want to check if two values I

mean if the first value should be either

greater or it should be equal

so we can put that uh equal to symbol

here as already discussed and now I can

just compile and run and you can say we

got true so this is working

we can also check for less than even

that works because it's equal right and

anyway we have equal so it should work

so we got true

uh we can also check if two values are

not equal example let's say I just want

to make sure that X and Y are not same

and the way you can do that here is by

saying not equal to so when we say not

it simply means it will uh when you say

exclamation it simply means dot so not

equal to Y and with this if I try to

compile and run you can say we got true

so even this is working but what if you

don't want to check for less than and

greater than you want to check if the

two values are exactly equal so in this

case normally in mathematics we use

equal to but that will not work here so

you have to use double equal to so you

are comparing x with Y and they should

be equal clear the screen compile and

run and you can see we got false the

reason we got false is because we have

both the different values so if I make

it same now and if I run this code

compile

and run and you can see we got true so

basically uh we we have different

operators and this will be used a lot in

the upcoming sessions uh so it doesn't

matter what type of programming you do

see when you say your computer has a

brain you know we have to decide based

on some values of course I have just

checked it with integer you can try it

with float as well in fact maybe I can

try with double so I can simply say

double here and I can say this is

8.8 and I can say double which is let's

say six maybe nine point eight and I can

just check if they are less than equal

to and of course I want you to try

different values there

and compile No it should run and you can

see we got true but if you check with

the greater than symbol this should give

you false

and we got false so basically whenever

you have a primitive value uh this

actually works uh maybe once we start

with string we also try to compare the

string values and let's see how that

turns out to be but this is your this is

how you do your traditional and

traditional operator checking with the

help of relational operators we got less

than greater than equal to symbol which

is double equal to not equal to that's

one yeah so this makes sense right but

what if you have two conditions example

let's say I got this values and now I

have int a equal to 8 and int b equal to

6. so I want to check if I mean I want

this x to be less than y and I also want

this a to be less than B I want to check

both the operation

and the thing is when we say I want to

check both the things should be true

then only it should print true how will

you do that how will you combine two