why doesn't the ImageIcon

  To: comp.lang.java.gui
I wrote a simple Swing program. When the click a button and select a jpg file, I want to show this picture in the JScollPanel, but it doesn't appear. The source is here:
private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
    if(evt.getSource() == this.jButton3) {
        JFileChooser chooser = new JFileChooser();
        chooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
        FileNameExtensionFilter filter = new FileNameExtensionFilter("JPG & GIF Images", "jpg", "gif");
        chooser.setFileFilter(filter);
        int returnVal = chooser.showOpenDialog(this);
        if(returnVal == JFileChooser.APPROVE_OPTION) {
            this.jTextField4.setText(chooser.getSelectedFile().getAbsolutePath());
            try{
                this.jScrollPane2.add(new ImagePanel(1, chooser.getSelectedFile()));
            } catch(Exception e) {
                e.printStackTrace();
            }
            
        }
    }
}

package auction.client;

import java.awt.Graphics;
import java.awt.Image;
import java.awt.geom.Point2D;
import java.io.File;
import java.io.IOException;
import java.util.HashSet;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JPanel;

public class ImagePanel extends JPanel {
    //identifier
    private int ID;
    
    //on-screen position
    private Point2D.Double position;
    
    //imageIcon to paint on screen
    private ImageIcon imageIcon;
    
    //stores all ImagePanel children
    private Set panelChildren;
    
    //constructor initilizes position and image
    public ImagePanel(int identifier, String imageFileName) throws IOException {
        super(null);//specify null layou
        this.imageIcon = this.createImageIcon(imageFileName);
        
        this.init(identifier);
    }
    
    public ImagePanel(int identifier, byte[] imageData) {
        super(null);
        this.imageIcon = this.createImageIcon(imageData);
        
        this.init(identifier);
    }
    
    public ImagePanel(int identifier, ImageIcon icon) {
        super(null);
        this.imageIcon = icon;
        
        this.init(identifier);
    }
    
    public ImagePanel(int identifier, File iconFile) throws IOException {
        super(null);
        this.imageIcon = this.createImageIcon(iconFile);
        
        this.init(identifier);
    }
    
    private void init(int identifier) {
        setOpaque(false);//make transparent
        
        // set unique identifier
        ID = identifier;
        
        // set location
        position = new Point2D.Double(0, 0);
        setLocation(0,0);
        
        Image image = imageIcon.getImage();
        setSize(image.getWidth(this), image.getHeight(this));
        
        //create Set to store Panel childre
        panelChildren = new HashSet();
    }
    
    private ImageIcon createImageIcon(String fileName) {
        try {
            return new ImageIcon(ImageIO.read(new File(fileName)));
        } catch (IOException ex) {
            Logger.getLogger(ImagePanel.class.getName()).log(Level.SEVERE, null, ex);
        }
        return null;
    }
    
    private ImageIcon createImageIcon(byte[] imageData) {
        return new ImageIcon(imageData);
    }
    
    private ImageIcon createImageIcon(File file) throws IOException {
        return new ImageIcon(ImageIO.read(file));
    }
    
    //paint Panel to scree
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        
        //if image is ready, paint it to screen
        imageIcon.paintIcon(this, g, 0, 0);
    }
    
    public void add(ImagePanel panel, int index) {
        panelChildren.add(panel);
        super.add(panel, index);
    }
    
    public void remove(ImagePanel panel) {
        panelChildren.remove(panel);
        super.remove(panel);
    }
    
    public void setIcon(ImageIcon icon) {
        this.imageIcon = icon;
    }

    public ImageIcon getImageIcon() {
        return imageIcon;
    }

    public Point2D.Double getPosition() {
        return position;
    }

    public void setPosition(double x, double y) {
        this.position.setLocation(x, y);
        this.setLocation((int) x, (int) y);
    }

    public int getID() {
        return ID;
    }
    
    public Set getChildren() {
        return panelChildren;
    }
    
}

Who can help me?

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