import java.awt.*;
import java.awt.event.*;
import java.lang.Thread;
import java.net.*;

public class prob6 extends java.applet.Applet implements Runnable {
  Image ball,squish;
  int loc;
  Thread t;
  public void start() {
    try {
      ball = getImage(new URL(getCodeBase()+"ball1.gif"));
      squish = getImage(new URL(getCodeBase()+"ball2.gif"));
      MediaTracker mt = new MediaTracker(this);
      mt.addImage(ball, 0);
      mt.addImage(squish, 0);
      mt.waitForAll();
    }
    catch(Exception e) { System.err.println("Exception "+e);return; }
    t = new Thread(this);
    t.start();
    super.start();
  }
  public void stop() {
    t.stop();
    super.stop();
  }
  public void run() {
    while(true) {
      for(loc = 0; loc <= 435; loc+=5) {
        repaint();
        t.yield();
      }
      for(;loc >= 5; loc-=5) {
        repaint();
        t.yield();
      }
    }
  }
  public void paint(Graphics g) {
    g.drawImage((loc>425 ? squish : ball), 50, loc, this);
    super.paint(g);
  }
}