Java hello world explained

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Our "Hello World!" program consists of three primary components:

• Source Code
• Comments
• Class definition
• Main method

Comments are ignored by the compiler but are useful to other programmers. 

/* MultiLine Comments */
/** Java Documentation Comments */
// Single Line Comments

Note : The compiler ignores everything from // to the end of the line.



Understanding Hello World

public : is an access modifier that means it will be accessed by every class out there
void : is a return type i.e it does not return any value
main() : is a method or a function name.

Program

/*
This is a multi
line comment
*/

// Single Line Comment

public class Program

{

    public static void main(String[] args)

    {

        System.out.println("Hello World");

    }

}

Compilation
$ javac Program.java

Execution
$ java Program