Code Samples from the Java Developers Almanac 2000

 import java.awt.*;
 import javax.swing.*;
     
 public class AnimApp extends JComponent 
   implements Runnable {
     Image[] images = new Image[2];
     int frame = 0;
     
     public void paint(Graphics g) {
       Image image = images[frame];
       if (image != null) {
         g.drawImage(image, 0, 0, this);
       }
     }  
     
     public void run() {
       images[0] = new ImageIcon(
         "image1.gif").getImage();
       images[1] = new ImageIcon(
         "image2.gif").getImage();
       int delay = 1000;    // 1 second
     
       try {
         while (true) {
                 frame = (frame+1)%images.length;
                     repaint();
                     Thread.sleep(delay);
          }
        } catch (Exception e) {
        }
     }
     
     public static void main(String[] args) {
       AnimApp app = new AnimApp();
       JFrame frame = new JFrame();
       frame.getContentPane().add(app);
       frame.setSize(300, 300);
       frame.setVisible(true);
     
       (new Thread(app)).start();
      }
 }