关于在applet中图片显示的问题，不知道如何解决

Question

import java.awt.*;
import java.applet.*;
import javax.swing.*;
import java.net.*;public class MyImageButton extends Applet {
Image image1;
String selectImage;
String unSelectImage;
//CustomCheckBox ccb;public void init()
{
ImageIcon icon1 =null ;
ImageIcon icon2 = null;
unSelectImage = "c:/images/b.gif";
selectImage = "c:/images/y.gif";
    try
    {
      URL url1 = new URL(unSelectImage);
      Image img1 = getImage(url1);
      Image img2 = getImage(new URL("c:/images/y.gif"));
      MediaTracker tracker;
      tracker = new MediaTracker(this);
      tracker.addImage(img1, 0);
      tracker.addImage(img2, 1);
      tracker.waitForID(0);
      tracker.waitForID(1);      icon1 = new ImageIcon(img1, "un");
      icon2 = new ImageIcon(img2, "select");
    }
    catch(Exception e)
    {
      e.printStackTrace();
    }
//ccb = new CustomCheckBox(unSelectImage,selectImage);
//add(ccb);
ButtonGroup group = new ButtonGroup();String description = "";
JRadioButton radio;
radio = new JRadioButton("", icon1);
radio.setIcon(icon1);
radio.setPressedIcon(icon2);
radio.setRolloverIcon(icon2);
radio.setRolloverSelectedIcon(icon2);
radio.setSelectedIcon(icon2);
radio.setMargin(new Insets(0,0,0,0));
group.add(radio);
add(radio);radio = new JRadioButton("", icon1);
radio.setIcon(icon1);
radio.setPressedIcon(icon2);
radio.setRolloverIcon(icon2);
radio.setRolloverSelectedIcon(icon2);
radio.setSelectedIcon(icon2);
radio.setMargin(new Insets(0,0,0,0));
group.add(radio);
add(radio);radio = new JRadioButton("", icon1);
radio.setIcon(icon1);radio.setPressedIcon(icon2);
radio.setRolloverIcon(icon2);
radio.setRolloverSelectedIcon(icon2);
radio.setSelectedIcon(icon2);
radio.setMargin(new Insets(0,0,0,0));group.add(radio);
add(radio);}}