import java.awt.*;
public class Eksam1 extends Frame implements Runnable{
 Pall1[] pallid;
 public Eksam1(){
 pallid=new Pall1[1];
 for(int i=0; i<pallid.length; i++)
  pallid[i]=new Pall1();
  setSize(200, 200);
  setVisible(true);
  new Thread(this).start();
 }
public void joonista(){
  Image pilt=createImage(200, 200);
  Graphics piltg=pilt.getGraphics();
  for(int i=0; i<pallid.length; i++){
    piltg.drawOval(pallid[i].x()-10, pallid[i].y()-10, 20, 20);
  }
  this.getGraphics().drawImage(pilt, 0, 0, this);
}
public void run(){
  while(true){
   joonista();
   Thread.yield();
   try{Thread.sleep(100);}catch(Exception e){}
   }
}
public static void main(String argumendid[]){
 new Eksam1();
 }
}
class Pall1 extends Thread{
  double x=200, y=200, dx, dy;
  int vasak=20, ulal=50, parem=200, all=200;
  public Pall1(){
    dx=5*Math.random();
    dy=5*Math.random();
    start();
  }
  public int x(){
    return (int)x;
  }
  public int y(){
     return (int)y;
  }
  public void run(){
    setPriority(Thread.NORM_PRIORITY-2);
    while(true){
       if(x>parem)dx=-Math.abs(dx);
       if(y>all)dy=-Math.abs(dy);
       if(x<vasak)dx=Math.abs(dx);
       if(y<ulal)dy=Math.abs(dy);
       x+=dx;
       y+=dy;
       yield();
        try{Thread.sleep(100);}catch(Exception e){}
        }
     }
}