import java.applet.Applet;
import java.awt.Graphics;

public class Circle extends Thread
{
   private  int x, y, radius=15;
   private  double dx = 2;
   private  double dy = 2;
   private  int width, height;
   private  Applet parent;


   //-------------------------------------------------------
   public Circle( Applet parent )
   {   this.parent = parent;
       //width  = parent.getSize().width;
       //height = parent.getSize().height;
       width  = parent.size().width;
       height = parent.size().height;
       x = radius + (int)Math.floor( (width - 2 * radius) * Math.random() );
       y = radius + (int)Math.floor( (height - 2 * radius) * Math.random() );
   }


   public void draw( Graphics g )
   {    g.fillOval( x, y, radius *2, radius * 2 );
   }

   public void move()
   {
         // Change position of Circle
         x += dx;
         y += dy;
         if (x<0) { x=1; dx=-dx; }
         if (x + 2*radius >= width) { x -= dx; dx=-dx; }
         if (y<0) { y=1; dy=-dy; }
         if (y + 2*radius >= height) { y -= dy; dy=-dy; }
         //System.out.println("Circle at: ("+ x + ", "+ y + ") ");
   }

   public void run()
   {    while ( true )
        { parent.repaint();

          try { Thread.sleep( 100 ); }
          catch ( InterruptedException e ) {}
        }
   }
}