Drag a JLabel, drop in a JList

Question

I'm trying to implement a drop-and-drag feature in my program.
I have a class Book, which extends a JLabel with and ID field (as a string) and a get and set method for the ID in it, as well as a toString method which returns the ID.
I need to drag the label over a JList and add the label's ID to the list, directly below the selected index over which the mouse dropped.
So far i have tried to override the transferhandler with example String and List handlers i found on the site (at http://java.sun.com/docs/books/tutorial/uiswing/misc/example-1dot4/ListTransferHandler.java and http://java.sun.com/docs/books/tutorial/uiswing/misc/example-1dot4/StringTransferHandler.java ) however, it seems the problem keeps getting bigger the more i try to edit them.
Also, i have tried to implement Serializable and Transferable Book's, but I'm not entirely familiar with how to use the dataflavors, so that could also be causing the problem.
I have tried a few possible scenarios with the transfer handler and so far this is getting me the most results:
public class dragtest extends JPanel {
public dragtest() {
super(new GridLayout(3,1));
add(createArea());
add(createList());
add(createBookcase(17));
private JPanel createList() {
DefaultListModel listModel = new DefaultListModel();
listModel.addElement("List one");
listModel.addElement("List two");
listModel.addElement("List three");
JList list = new JList(listModel);
list.setSelectionMode(ListSelectionModel.SINGLE_INTERVAL_SELECTION);
JScrollPane scrollPane = new JScrollPane(list);
scrollPane.setPreferredSize(new Dimension(400,100));
// do not allow list items to be dragged
list.setDragEnabled(false);
// list.setDropTarget();
// DropTarget dt = new DropTarget();
// list.setDropTarget(dt);
list.setTransferHandler(new ListTransferHandler());
JPanel panel = new JPanel(new BorderLayout());
panel.add(scrollPane, BorderLayout.CENTER);
panel.setBorder(BorderFactory.createTitledBorder("List"));
return panel;
private JPanel createBookcase(int amount) {
JPanel bookCase = new JPanel();
int X1 = 30; // height from top
int X2 = 20; // height to bottom
int Y1 = 20; // distance from sides
int Y2 = 10; // distance between images
int Z1 = 60; // width of image
int Z2 = 80; // height of image
int numLabelsInCol = 5;
int numDone = 0;
int x = 0;
for (int y = 0; y < numLabelsInCol; y++) {
if (numDone < amount) {
Book lbl = new Book(numDone, "address");
lbl.setBounds( (Y1 + y * (Z1 + Y2)), (X1 + x * (Z2 + X2 + X1)), Z1, Z2);
bookCase.add(lbl);
String text = lbl.ID;
lbl.setText(text);
numDone++;
lbl.setTransferHandler(new TransferHandler("text"));
MouseListener listener = new DragMouseAdapter();
lbl.addMouseListener(listener);
bookCase.setPreferredSize(new Dimension(400, 100));
return bookCase;
private class DragMouseAdapter extends MouseAdapter { public void mousePressed(MouseEvent e) {
JComponent c = (JComponent) e.getSource();
TransferHandler handler = c.getTransferHandler();
handler.exportAsDrag(c, e, TransferHandler.COPY);
I realise it might be a little unconventional, the way i implement the transfer handler, but this actually prints out the ID on a JTextArea, however a list does not even react when i drag or drop the label over it. It does not even show a shaded area under which the mouse is.
I have tried a multitude of examples but none of them have dealt with this. The only one which deals with JLabels dropped on a JList does not care for the order, however my program focuses on it.
Please could anyone help?

Answer 1

1) Swing related questions should be posted in the Swing forum
2) When you poste code use the "code" formatting tags so the code retains its original formatting
Using the ExtendedDnDDemo, from the Swing tutorial you referenced above, as the test program I created the following method:
    private JPanel createLabel() {
         JLabel label = new JLabel("Dnd Label");
        label.setTransferHandler(new LabelTransferHandler());
        label.addMouseListener( new MouseAdapter()
             public void mousePressed(MouseEvent e)
                 JComponent c = (JComponent)e.getSource();
                 TransferHandler handler = c.getTransferHandler();
                 handler.exportAsDrag(c, e, TransferHandler.COPY);
        JPanel panel = new JPanel(new BorderLayout());
        panel.add(label, BorderLayout.CENTER);
        panel.setBorder(BorderFactory.createTitledBorder("Label"));
        return panel;
    }And the following class:
* LabelTransferHandler.java is used by the 1.4
* ExtendedDnDDemo.java example.
import javax.swing.*;
import java.awt.*;
import java.awt.datatransfer.*;
public class LabelTransferHandler extends StringTransferHandler {
    // Get the text for export.
    protected String exportString(JComponent c) {
        JLabel label = (JLabel)c;
        return label.getText();
    //Take the incoming string and set the text of the label
    protected void importString(JComponent c, String str) {
        JLabel label = (JLabel)c;
        label.setText(str);
    protected void cleanup(JComponent c, boolean remove) {
}