#5 Variables in Java

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In this lecture we will learn:
- Working of Java code
- How is data stored in a database?
- What are variables?
- Syntax of variables
#1
-As a Java developer you write a Java code that will be having .java extension and that gets compiled by javac.
- When you compile that code what you get in output is a byte code that has .class file.
- Whenever you run .class file in the JVM, it means that it's a part of JRE that has JVM as well as libraries and a lot of classes, and JRE is installed on the OS.
- So, you need a hardware or machine having OS and then OS will have JRE and it has JVM. As a developer, one more tool is required known as JDK.
When you will install the new JDK, you will get updated JRE and JVM with it.
- We are using JDK version 17 in this course because of its long-term support.
- We develop software to solve real-world problems using the virtual world.
e.g., Amazon
#2
- Whenever we build a project or an application what we are doing is we are processing the data.
- Data may come from the user and then we do processing on it. A database is used to store the data and processing done on it.
- Database is permanent or persistent storage which means data will remain there if the machine gets shut down.
#3 Variables:-
- Variable is used to store the data temporarily while processing.
- Variable is a type of box in which you store data and a type is attached to it such as type can be number, text, image, etc. Thus, a box is known as a variable and a name and value are present with it.
- A variable is a container that holds the value while the Java program is executed.
- Java is a strongly-typed language as it demands the declaration of every variable with a data type.
- Syntax of creating a variable:
datatype variable name = value;
int num1= 3;
- Here, (=) is the assignment operator that takes the right-hand side value and assigns it to the left-hand side.
- println is used to go or print on the new line.
- In Java, every statement ends with a semicolon except blocks.
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[@sofiavillaverde7006]

Your content is better than most professors I’ve had in college! Great explanation and content!

[@user-sl3ej5mw6w]

Your content is well explained here, I never understood Java until I have watched your videos. thanks so much for this great explanation.

[@rajumallick8779]

00:03 Java development process and required tools. 01:39 Software is built to solve real-world problems using virtual solutions 03:13 Data can be stored temporarily in variables during processing. 04:33 Java variables are used to store data 06:03 Integers are used to store whole numbers, including negative values 07:27 Using 'print Ln' in Java to print on new lines 08:53 Create variables and assign values in Java 10:18 We can create variables to store and manipulate values.

[@codenissi]

That is a fantastic explanation, happy I got this course and had understanding about java.

[@SuriSyam2709]

you are a life saver of many students sir.....

[@kirankumarsb6507]

Great work sir, It will helpful for infinity of students ✨.

[@simonason9342]

For anyone who have the issue "Error: Could not find or load main class Hello Caused by: java.lang.ClassNotFoundException". I solved this by: 1 Save my project, 2 Type "javac Hello.java" in terminal "push" "enter", 3 Type "java "(classname)" in terminal "push" "enter" This made it calculate for me. I have no coding experience or how you use the symbole language so I hope you can follow the steps.

[@sumiluckymikkubasant]

i got it thanks

[@Jerrryy713]

Thanks bro i was suffering from past 15 min from this 🤌🏻😩

[@Jerrryy713]

Bro isn't there a way were i dont have to save program everytime...if you could help 😅

[@rupesh171kumar]

Sir whick jvm are you using to run java

[@NaveenMaddela-yr4gb]

U r a gem dude, u should be in IIT's. Remembering all the stuff from college days. U r better then many lectures & professors ( It's not mean they are not worthy, but u r next level in explanation) It's very easy to understand and remember more stuff in simple way.

[@pinkprint3686]

I'm so glad I've found your videos! Super interesting! Thank you so much!

[@andreas23ds41]

Guys when I try it and use javac it makes and new byte bode instead of saving in the first file and when I want to run it error happens

[@basudevpaul8417]

Enjoy your Content, Your content is great kudos 👏👏👏👏

[@theamritjha755]

Thanku for this type of content sir ❤️🙏

[@naseddinoufallah628]

Hi, i want code hhhhhhhh, ehere is code i can see that can you show me

[@joshnasrikuchhe777]

Thank you so much brother

[@rssvprasad9859]

Thank you anna

[@mohdfaizaanuddin510]

= is a Assignment operator Assignment operator takes value from Right Hand side and it will assign it to the left hand side. Syntax of Declaring a Variable Variabletype variablename = value 2) Every Statement must end with a Semi colon.

[@otienoodhiambo5952]

i love this you are great lecturer

[@Ali-qy5lk]

"Could not find or load main class Hello" - Any fix for this?

[@deepakmallareddy6683]

Click on (Run without Debugging) at the top of the editor or right click on the code and choose the run Java option.

[@suraprashanthreddysura487]

what is happening when we are not storing values in the variable ,where the data is storing now? like S.O.P(2+3) do 2 require space and do 3 require space and the 5 require space if yes then where it is actually getting stored.

[@manojarya7676]

It's not getting stored anywhere.. simply giving the result by jvm

[@misaonthefly]

The data is stored in ram anyways... but it cannot be retrievable for later use... so it makes sense... if you are not gonna use a value more than once... don't save it in a variable

[@TheKenWiley]

I do not have JavaC show up when I type java -version. How do I get that installed in my system? Everytime I try to run anything, like the basic sample above, I get "missing package" and/or "system" not resolved errors. What is missing? Libraries not found? How do I correct this?

[@KHAREMAKARANDVASANT]

When you download and unzip JDK and add the path of the bin folder inside to the "path" system environment variable, it should work.

[@shreyashlawate9970]

sir when I do changes in my code and compile it it shows the old result not the new why it is happening?? like when we added 3+5 and 8+7 it gives output only 8

[@martinamillo969]

1 save the code by using CTRL+S or by clicking on File --> Save on top left of the screen. 2 compile the new code by writing on the terminal "javac Hello.java" 3 run it with "java Hello" In this way it should work.. anytime you change the code before compiling it you have to save the changes then compile it and then run it.

[@0x.]

@@martinamillo969 you're actually too helpful thank you

[@Shubham-fk4is]

Nice

[@user-te6km7hz6p]

i compiled it and ran still its showing hello world instead of 8 any solution to this

[@majeedabdulla8798]

same is there any solution you know of?

[@majeedabdulla8798]

I have recompliled and even deleted the old one but still wasn't getting 8 as an answer still getting hello world any clue to fix this.

[@eternalexplorer4471]

Save the code and then compile and run

[@yashchavan7384]

thx @@eternalexplorer4471

[@kalyanmondal3468]

❤​@@eternalexplorer4471

[@chillboy3650]

Nice sir

[@manojKumar-si4ml]

println() is method right and we are sending operations as arguments to that method. How println() taking those as arguments. Ex: whether it taking as string , its taking as string you need to mention those in "" right.

[@shobhithjb4626]

Actually There are multiple variations of println() available which takes int, float, long, String as arguments. Like println(String x), println(int x).... etc.

[@yamaladeepika2086]

while i am executing the code i am getting an error called class was not found even though i create class name hello

[@ArikeriUsha-yz8qv]

Why coming error

[@ArikeriUsha-yz8qv]

What is the error

[@LearnJava_Programming]

Everyone seems to be getting the same error and I did as well. Just delete the code runner extension in VS code. This should fix the error

[@prabhutvawakodkar3620]

hii i am facing a problem when i tried to compile the code, it was printing the earlier code i.e. Hello World. what can i do for that? how can i solve the problem? please help me

[@umarawat12]

Firstly you have to save the code and then run

[@challacharan1648]

even though i changed the "Hello World" with (3 + 5) i could not get 8 instead again i am getting Hello World in terminal (ANY SOLUTION FOR THIS PLEASE REPLY QUICK)

[@user-im6vi8wt7i]

compile it first and then run it

[@majeedabdulla8798]

compiled it and it still didnt change?@@user-im6vi8wt7i

[@sunmethasunmetha3502]

Save it and then compile and run

[@martinamillo969]

thanks you really saved me!!! @@sunmethasunmetha3502

[@sahilpatildreamer]

Very helpful

[@venkivenkatesh83]

I am fresher, sir please send me the Java important questions

[@martinamillo969]

So following this lesson, i wanted to create a VARIABLE for text. So I created this code 1 class Hello 2 { 3 public static void main(String a[]) 4 { 5 String name = Martina; 6 System.out.print(name); 7 } 8 } When i compile it , it shows these errors Hello.java:5: error: cannot find symbol String name = Martina; ^ symbol: variable Martina location: class Hello 1 error Anyone knows why ?

[@aktharishaik]

String values should be stored in double quotes(" ") : String name = "Martina"

[@mahidhar6247]

" "

[@b.o.8557]

👍

[@sreesanth20]

class Hello { public static void main(String a[]) { System.out.println(3 + 5); } } for this code what i get is "Hello world" even after complier

[@yasmeenshahana4860]

Once try again I got the answer

[@ritikraj6523]

first save the code by cntrl+s then try

[@andreas23ds41]

Bro it's not working ​@@ritikraj6523

[@Theamanbasnet]

@@ritikraj6523 thanks

[@pow3rche]

5:37

[@mohammedabdulkarim9878]

Am facing an error of which (Error: Could not find or load main class Hello Caused by: java.lang.ClassNotFoundException:) can anyone help me out please.

[@gopalkrishnan474]

Instead of typing the file name you created, type the class name.( For ex: java Hello).... this is name of the class here, not the file name you edit

[@dreadhunter7114]

same problem how did u solved it

[@dreadhunter7114]

@@gopalkrishnan474 bro im having the same problem could u explain it more specificly

[@gopalkrishnan474]

@@dreadhunter7114 Dont type the name of the file, but the class name you created

[@benjikoy]

make sure you are in the correct directory when you run the command. if you used a package go to the location and run the command from there. javac /packagename/classname.java then java /packagename/classname

[@anirudhgoyal5603]

hi

[@AntarikshRajkonwar]

12/5/24

[@Nkhugkvivnihy]

video lambi boht kartaha itu

[@stranger2k]

Thank you sir.

[@aszaw5342]

is possible to run the code without compiling ? java hello.java

[@challacharan1648]

no

[@rohit8hjj]

yes its possible