The Rotating Disk Applet:


Code:

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

public class Rotating_Disk extends Applet
{
   //===========================================================
   //  Uses ovals to simulate a rotating disk.
   //===========================================================
   public void paint (Graphics page)
   {
      int width = 0, height = 60;   // initial size
      int x = 120, y = 120;         // position
      int warp = 1;                 // shrink/growth factor
       
      page.setXORMode (getBackground());

      for (int change=1; change < 500; change++)
      {
         width = width + warp * 2;
         x = x - warp;

         if (width == 0 || width == 60)
            warp *= -1;  //switch between growing and shrinking 
        
         // print oval
         page.fillOval (x, y, width, height);

         for (int pause=1; pause <= 1000000; pause++);

         // erase oval
         page.fillOval (x, y, width, height);
      }
   }
}