Swing, Drog and Drop, Transfer Handlers...

Question

I am writing a game that involves dragging and dropping pegs into various holes. Right now I have a bunch of JLabels that act as bins and a bunch of JLabels that act as holes. All the JLabels have a TransferHandler of type icon set:
xxx.setTransferHandler(new TransferHandler("icon"));
The bins have a mouse listener set following the example for adding dnd to swing components without default dnd support:
MouseListener ml = new MouseAdapter() {
public void mousePressed(MouseEvent e) {
JComponent c = (JComponent)e.getSource();
TransferHandler th = c.getTransferHandler();
th.exportAsDrag(c, e, TransferHandler.COPY);
binsxxx.addMouseListener(ml);
The transfer handler sets up both source and target capabilities, which I dont want for the bins so I created a DropTarget, disabled it and set the bins droptarget to that:
DropTarget dt = new DropTarget();
dt.setEnable(false);
binsxxx.setDropTarget(dt);
With these few snippets of code, I can drag a peg (an icon) from bin to hole.
Finally, onto my question. I know from browsing through he awt.dnd package that there is the capablity of adding an icon to follow the cursor on a drag event. Can I easily add this feature to my program without nullifying the default transferHandler behavior (ie requiring me to go and muck around with the awt.dnd stuff directly)?

Answer 1

I was wondering if you got to the bottom of this exception?
I'm implementing dnd between two JTrees in a splitpane & I'm seeing the same exception when the drag leaves a tree. Any suggestions would be greatly appreciated.
java.lang.NullPointerException
     at javax.swing.plaf.basic.BasicTreeUI$TreeDropTargetListener.restoreComponentState(Unknown Source)
     at javax.swing.plaf.basic.BasicDropTargetListener.dragExit(Unknown Source)
     at javax.swing.TransferHandler$SwingDropTarget.dragExit(Unknown Source)
     at sun.awt.dnd.SunDropTargetContextPeer.processExitMessage(Unknown Source)
     at sun.awt.dnd.SunDropTargetContextPeer.access$700(Unknown Source)
     at sun.awt.dnd.SunDropTargetContextPeer$EventDispatcher.dispatchExitEvent(Unknown Source)
     at sun.awt.dnd.SunDropTargetContextPeer$EventDispatcher.dispatchEvent(Unknown Source)
     at sun.awt.dnd.SunDropTargetEvent.dispatch(Unknown Source)
     at java.awt.Component.dispatchEventImpl(Unknown Source)
     at java.awt.Container.dispatchEventImpl(Unknown Source)
     at java.awt.Component.dispatchEvent(Unknown Source)