java ImageIcon enkel fråga

import javax.swing.*;
import java.awt.*;
import java.net.*;

public class DynamicImageIcon extends ImageIcon{
    private JComponent p;
    
    public DynamicImageIcon(String filename){
        super(filename);
    }
    
    public DynamicImageIcon(URL location){
        super(location);
    }
    
    public DynamicImageIcon(Image image){
        super(image);
    }
    
    public void setParent(JComponent parent){
        p = parent;
    }
    
    public Dimension getIconSize(){
        // räkna ut bildens ursprungsstorlek
        int iw = getImage().getWidth(component),
            ih = getImage().getHeight(component);
        if(p==null)
            return new Dimension(iw, ih);
        else{
            int pw, ph;
            pw = p.getWidth() -p.getInsets().left-p.getInsets().right;
            ph = p.getHeight()-p.getInsets().top - p.getInsets().bottom;
           if(pw/(double)ph <iw/(double)ih)
               return new Dimension(pw, pw*ih/iw);
           else
               return new Dimension(ph*iw/ih, ph);
        }
    }
    
    public int getIconWidth(){
        return getIconSize().width;
    }
    
    public int getIconHeight(){
        return getIconSize().height;
    }
    
    public void paintIcon(Component c, Graphics g, int x, int y){
        g.drawImage(getImage(), x, y, getIconWidth(), getIconHeight(), component);
    }
}
class ImagePlayer extends JFrame{
    ImagePlayer(){
        DynamicImageIcon d1 = new DynamicImageIcon("hund.gif");
        DynamicImageIcon d2 = new DynamicImageIcon("exit.gif");
        DynamicImageIcon d3 = new DynamicImageIcon("hammer.gif");
        JLabel l1 = new JLabel(d1, JLabel.CENTER);
        JLabel l2 = new JLabel(d2, JLabel.CENTER);
        JLabel l3 = new JLabel(d3, JLabel.CENTER);
        d1.setParent(l1); d2.setParent(l2); d3.setParent(l3);
        setLayout(new GridLayout(1,3));
        add(l1); add(l2); add(l3);
        setVisible(true);
        pack();
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        
    }
    
    public static void main (String[]args){
        new ImagePlayer();
    }
}