Java Program Hello World with starting intro

We break the process of programming in Java into three steps:

1. Create the program by typing it into a text editor and saving it to a file named, say, MyProgram.java.
2. Compile it by typing "javac MyProgram.java" in the terminal window.
3. Run (or execute) it by typing "java MyProgram" in the terminal window.

The first step creates the program; the second translates it into a language more suitable for machine execution (and puts the result in a file named MyProgram.class); the third actually runs the program.


Creating a Java program. A program is nothing more than a sequence of characters, like a sentence, a paragraph, or a poem. To create one, we need only define that sequence characters using a text editor in the same way as we do for e-mail. HelloWorld.java is an example program. Type these character into your text editor and save it into a file named HelloWorld.java.

public class HelloWorld { 
   public static void main(String[] args) { 
      System.out.println("Hello, World");
   }
}

Compiling a Java program.
At first, it might seem to you as though the Java programming language is
designed to be best understood by the computer.
Actually, to the contrary, the language is designed to be best understood
by the programmer (that's you).

A compiler is an application that translates programs from the
Java language to a language more suitable for executing on the computer.
It takes a text file with the .java extension as input (your
program) and produces a file with a .class extension (the 
computer-language version). To compile HelloWorld.java type
the boldfaced text below at the terminal. (We use the % symbol
to denote the command prompt, but it may appear different depending
on your system.)



%
javac HelloWorld.java 
 
If you typed in the program correctly, you should see no error messages.
Otherwise, go back and make sure you typed in the program exactly as
it appears above.

Executing a Java program.
Once you compile your program, you can run it.
This is the exciting part, where the computer follows your instructions.
To run the HelloWorld program, type the following at the terminal:






%java HelloWorld




If all goes well, you should see the following response




Hello, World