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

public class flimmer extends Applet implements Runnable {
	private Thread	animatorThread = null;
  private int posX, posY;             // Position
  private int incx=1, incy=1;         // Richtungszuwachs
  private final int rad = 20;
  private Image offScreenBuffer;
  private Graphics offScreenGraphics; // Grafik kontext für den offScreenBuffer.

  public void init(){
    offScreenBuffer = this.createImage(size().width , size().height);
    // Wir müssen unser Buffer-Image als Graphics object benutzen:
    offScreenGraphics = offScreenBuffer.getGraphics();
  }


  // Überschreiben der Methode Paint()
	public void paint(Graphics g) {
    g.setColor(Color.black);
    g.fillRect(0,0,size().width, size().height);
	  //g.clearRect(0,0,size().width, size().height);
    g.setColor(Color.cyan);
    g.create().fillOval(posX-rad-3*incx ,posY-rad-3*incy ,rad*2 ,rad*2 );

    g.setColor(Color.blue);
    g.create().fillOval(posX-rad ,posY-rad ,rad*2 ,rad*2 );
  }

  public void run() {
   while (Thread.currentThread() == animatorThread){
      posX+= incx;
      posY+= incy;
      if ((posX <= rad) || (posX >= size().width-rad))
        incx*=-1;
      if ((posY <= rad) || (posY >= size().height-rad))
        incy*=-1;
      repaint();

      try {
			  Thread.sleep(10);
      }
      catch(InterruptedException e){
	  	  showStatus("Error: " + e.toString());
      }
    }
  }

	public void start() {
		if(animatorThread == null) {
			animatorThread = new Thread(this, "Test Thread");

      posX = (int)(size().width/2);
      posY = (int)(rad*2);
      incx = (Math.random() < 0.5) ? 2 : -2;
      incy = (Math.random() < 0.5) ? 2 : -2;
 			animatorThread.start();
		}
	}

	public void stop() {
		animatorThread = null;
	}      

}