Introduction to Programming in Java

This page extends on the previous resource to delve deeper into Java itself, relating its use to its history.

5. "Hello World"

Anytime you learn a computer programming language, it is tradition that the first program you write should be to make your computer say, "Hello World". This is a small feat, but is a good opportunity to make sure that you installed the JDK properly.

The Java compiler reads basic text files. Open up a text editor like Notepad (Don't use a complex program like Word for this). Type this code, remembering that Java is case-sensitive:

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

Save this file as HelloWorld.java. Start your system's command line and navigate to the folder that you saved HelloWorld.java to. Type javac HelloWorld.java. This runs the java compiler, javac, and creates a class file, which contains the bytecode for the application. Next type java -cp . HelloWorld. This runs the class file that was just created by the compiler. Your console should print:

Hello World!