Thread by @meetjain74

Writing your first Java program??

🔸How to compile and run it
🔸What does "Public Static Void Main" mean

A thread🧵

(1/11)
A simple Java program

(2/11)
How to save a Java program?

The program name must be saved as the class name in which the main function is declared.
Extension -> .java
Example here: First.java

(3/11)
How to compile a Java program?

To compile the program, we use -
javac First.java

After compilation, the .java file gets translated into the .class file called "bytecode"
Now we can run the program

(4/11)
How to run a Java program?

To run the program, type the command -
java First

We should not append the .java extension to the file name while running the program

(5/11)
Fact about a Java program

Every program in Java must be enclosed within a class.

(6/11)
Terms of a Java Program

You might have come across the following words in every Java program -
🔹public
🔹static
🔹void
🔹mean
🔹Strings args[]

But what do they mean?
Let us understand

(7/11)
Why is the main method public?

'public' keyword is an access specifier which allows the programmer to control the visibility of class members.
main() is declared as public since it must be called by code outside of its class when the program is started.

(8/11)
Why is the static keyword used?

The 'static' keyword allows main() to be called without having to instantiate a particular instance of the class.

This is necessary since main() is called by the Java interpreter before any objects are made.

(9/11)
What does 'void' mean?

The keyword 'void' simply tells the compiler that main() does not return a value.

(10/11)
What does the parameter String args[] in the main() method means?

String args[] is an array of instances of the class String which receive command-line arguments present when the program is executed.

(11/11)
How to print in Java?

To print in Java, we use -
🔹System.out.print("Hello") - without a new line
🔹System.out.println("Hello") - with a new line

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