Simple Java Program

Here is an example Java program. It is about as small as a Java program can be. When it runs, it writes Hello World! on the computer monitor. The details will be explained later.

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

This program can be created using a text editor such as the Notepad editor that comes with Windows. (Details later.) This source program is a text file saved on a hard disk. The file is named Hello.java.

A source program is a text file that contains a program (such as above) written in a programming language. Since it contains ordinary text (stored as bytes) it can not be directly executed (run) by the computer system. As a text file, you can print it, display it on the monitor, or alter it with a text editor.