import java.awt.*;
import java.awt.event.*;

public class Example2411
extends Frame
implements Runnable
{
   private Thread th;
   private int actx;
   private int dx;
   private int actarc1;
   private int actarc2;
   private Image dbImage;
   private Graphics dbGraphics;

   public static void main(String[] args)
   {
      Example2411 frame = new Example2411();
      frame.setSize(210,170);
      frame.setVisible(true);
      frame.startAnimation();
   }

   public Example2411()
   {
      super("Example2411");
      //WindowListener
      addWindowListener(
         new WindowAdapter() {
            public void windowClosing(WindowEvent event)
            {
               if (th != null) {
                  th.stop();
                  th = null;
               }
               setVisible(false);
               dispose();
               System.exit(0);
            }
         }
      );
   }

   public void startAnimation()
   {
      Thread th = new Thread(this);
      th.start();
   }

   public void run()
   {
      actx = 50;
      dx = 5;
      actarc1 = 0;
      actarc2 = 0;
      while (true) {
         repaint();
         actx += dx;
         if (actx < 0 || actx > 100) {
            dx = -dx;
            actx += 2*dx;
         }
         actarc1 = (actarc1 + 1) % 360;
         actarc2 = (actarc2 + 2) % 360;
         try {
            Thread.sleep(40);
         } catch (InterruptedException e) {
            //nichts
         }
      }
   }

   public void update(Graphics g)
   {
      //Double-Buffer initialisieren
      if (dbImage == null) {
         dbImage = createImage(
            this.getSize().width,
            this.getSize().height
         );
         dbGraphics = dbImage.getGraphics();
      }
      //Hintergrund löschen
      dbGraphics.setColor(getBackground());
      dbGraphics.fillRect(
         0,
         0,
         this.getSize().width,
         this.getSize().height
       );
      //Vordergrund zeichnen
      dbGraphics.setColor(getForeground());
      paint(dbGraphics);
      //Offscreen anzeigen
      g.drawImage(dbImage,0,0,this);
   }

   public void paint(Graphics g)
   {
      int xoffs = getInsets().left;
      int yoffs = getInsets().top;
      g.setColor(Color.lightGray);
      g.fillOval(xoffs+actx,yoffs+20,100,100);
      g.setColor(Color.red);
      g.drawArc(xoffs+actx,yoffs+20,100,100,actarc1,10);
      g.drawArc(xoffs+actx-1,yoffs+19,102,102,actarc1,10);
      g.setColor(Color.blue);
      g.drawArc(xoffs+actx,yoffs+20,100,100,360-actarc2,10);
      g.drawArc(xoffs+actx-1,yoffs+19,102,102,360-actarc2,10);
   }
}