Create a file named myJavaApp.java.

~]# touch myJavaApp.java

Add the following markup to myJavaApp.java.

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

Compile myJavaApp. This will create a new file named myJavaApp.class.

~]# javac myJavaApp.java

Execute myJavaApp, and "Hello World" should be displayed.

~]# java myJavaApp
Hello World