From Java source to execution

Compiling a Java program

Using javac

javac [filename].java

Executing a Java program

Stand-alone program (java)

java [classname]

Applet (appletviewer)

Create an html page with <applet code="[classname].class" width="" height=""> (code, width, and height are required)
appletviewer [page].html

Example (stand-alone)

Source code (hello.java):

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

Compiling and Executing:

javac hello.java
java hello
Hello

Example (applet)

Source code (hello_applet.java):

import java.awt.Graphics;

public class HelloWorld extends java.applet.Applet {
   public void paint(Graphics g) {
      g.drawString("Hello", 50, 25);
   }
}

HTML code (hello_applet.html):

<applet code="hello_applet.class" width="100" height="50">
</applet>

Compiling and Executing:

javac hello_applet.java
appletviewer hello_applet.html