Simple Java Program for beginners (HelloWorld.java)

Writing a simple Hello World program is stepwise step. This short example shows how to write first java application and compile and run it. I am assuming that latest version of JDK is installed on your machine



HelloWorld.java - the source code for the "Hello, world!" program

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

How to save
To run this program, save it in a file with the name HelloWorld.java. It must be sure that the file name must match the name of the class.

Compile the program

javac HelloWorld.java command is used to compile the source code.
When you compile the program you'll create a byte-code file named HelloWorld.class.
You can confirm this with the dir command in the DOS/Windows world.

Execute the byte code
Now you can execute the byte code in the Java interpreter with this command:
java HelloWorld
Output of the program
When you run the program at the command line, you'll see this output
Hello, world!