Hello World Applet in Java

Here is everybody's favorite program in Java, this time as an applet:

import java.applet.*;
import java.awt.*;

public class HiWorld extends Applet
{
  public void paint (Graphics g)
  {
    g.drawString ("Hi, world!", 50, 100);
  }
}

This time, however, you need the following additional file:

<html> <head> <title> Hi World Applet </title> </head> <body> <applet code="HiWorld.class" width=300 height=200></applet> </body> </html>

To run this program,

Copy the Java applet exactly as written onto a file named HiWorld.java. (If you are on a PC, you may need to name the file HiWorld.jav.) Do not give the file some other name.
Copy the HTML onto a file. HiWorld.html is the name used in this example, but it really doesn't matter.
Compile the file by putting it in the same directory as the compiler and issuing the command
javac HiWorld.java
This should create a file named HiWorld.class (I'm not sure what it is if you only have 3-character extensions.)
Run the file either by issuing the command
appletviewer HiWorld.html
or by opening the file HiWorld.html in your favorite browser. (Make sure Java is enabled in your browser.)
This should print "Hi, World!"

Notes

Java cares what file name you use. If your class is named HiWorld, then it must be in a file named HiWorld.java. For PCs that can't have a four-letter extension, the name must end in .jav instead. If your operating system has case-sensitive file names, the first part of the file name (HiWorld in this case) must be capitalized the same way as in your program.
The Java compiler javac requires the name of the file (as you would expect), that is, HiWorld.java.
Neither appletviewer nor your browser cares what the name of your HTML file is; it only cares that the name specified after code= is correct.