Unable to drag the Icon associated with the node

Question

I am working on dragging a node from Tree to a list.
I have to drag the Icon associated with the leaf too. I am able to drag only the string of the node not the Icon that is associated with it. Can you help me with this? I have the code as below. Thanks.
public class IconNode extends DefaultMutableTreeNode {
protected Icon icon;
protected String iconName;
//* IconNode
/**Creates an IconNode Object*/
public IconNode() {
this(null);
}//end IconNode
//* IconNode
/**Creates an IconNode Object*/
public IconNode(Object userObject) {
this(userObject, true, null);
}// end IconNode
//* IconNode
/**Creates an IconNode Object*/
public IconNode(Object userObject, boolean allowsChildren
          , Icon icon) {
super(userObject, allowsChildren);
this.icon = icon;
}//end IconNode
//* setIcon
/**sets the Icon to the node*/
public void setIcon(Icon icon) {
this.icon = icon;
}// end setIcon
//* getIcon
/**gets the Icon of the node*/
public Icon getIcon() {
return icon;
}//end getIcon
//* getIconName
/**gets the IconName*/
public String getIconName() {
if (iconName != null) {
return iconName;
} else {
String str = userObject.toString();
int index = str.lastIndexOf(".");
if (index != -1) {
return str.substring(++index);
} else {
return null;
}//end getIconName
//* setIconName
/**sets the IconName*/
public void setIconName(String name) {
iconName = name;
}//end setIconName
}// end IconNodepublic class IconNode extends DefaultMutableTreeNode {
protected Icon icon;
protected String iconName;
//* IconNode
/**Creates an IconNode Object*/
public IconNode() {
this(null);
}//end IconNode
public class DNDTree extends JTree
public DNDTree (IconNode top)
super (top);
DNDTreeHandler dndHandler = new DNDTreeHandler(this);
setAutoscrolls(true);
public class DNDTreeHandler extends DnDHandler
TransferableDataItem transDataItem = new TransferableDataItem();
public DNDTreeHandler(Component dndComponent)
super(dndComponent);
public DataFlavor[] getSupportedDataFlavors()
return transDataItem.getTransferDataFlavors();
* Gets the data from the selected object being dragged
* @return node DataItem being dragged
public Transferable getTransferable()
TreePath path = getSelectionPath();
//DefaultMutableTreeNode selection = (DefaultMutableTreeNode)path.getLastPathComponent();
IconNode selection = (IconNode)path.getLastPathComponent();
if (path == null)
return(null);
else
TransferableDataItem node = new TransferableDataItem(selection);
return(node);
* Handles the drop of the component after the drag is complete
* @param transferable Object being dropped
* @param event drop event information
public void handleDrop(Transferable transferable, DropTargetDropEvent event) throws Exception
Point location = event.getLocation();
//Get path of node where object being dropped
TreePath path = getClosestPathForLocation(location.x, location.y);
//No drop target
if(path == null)
System.err.println ("Rejected");
event.rejectDrop();
else
Transferable tr = event.getTransferable();
if(tr.isDataFlavorSupported(TransferableDataItem.DEFAULT_MUTABLE_DATAITEM_FLAVOR))
System.out.println("Got transfered data");
Object userObject = tr.getTransferData(TransferableDataItem.DEFAULT_MUTABLE_DATAITEM_FLAVOR);
//DefaultMutableTreeNode node = (DefaultMutableTreeNode)path.getLastPathComponent();
IconNode node = (IconNode)path.getLastPathComponent();
IconNode newNode = new IconNode(userObject);
DefaultTreeModel model = (DefaultTreeModel)getModel();
model.insertNodeInto(newNode, node, 0);
else
System.err.println ("Rejected");
event.rejectDrop();
public abstract class DnDHandler implements DropTargetListener,DragSourceListener, DragGestureListener
protected DropTarget dropTarget;
protected DragSource dragSource;
public DnDHandler(Component dndComponent)
dropTarget = new DropTarget (dndComponent, this);
dragSource = new DragSource();
dragSource.createDefaultDragGestureRecognizer( dndComponent, DnDConstants.ACTION_COPY_OR_MOVE, this);
//creates transferable based on what's selected or returns null if nothings selected
protected abstract Transferable getTransferable();
protected abstract void handleDrop(Transferable transferable, DropTargetDropEvent event) throws Exception;
protected abstract DataFlavor[] getSupportedDataFlavors();
public void dropFailed (DragSourceDropEvent event)
System.out.println("Drop Failed");
public void dropSuccess (DragSourceDropEvent event)
System.out.println("Drop was successful");
private boolean isTransferableSupported(Transferable t)
DataFlavor[] flavors = getSupportedDataFlavors();
for (int i=0; i<flavors.length; i++)
if (t.isDataFlavorSupported(flavors) )
return true;
return false;
public void dragGestureRecognized( DragGestureEvent event)
Transferable trans = getTransferable();
Cursor dragIcon = getDragCursor(event);
if (trans != null)
// Starts the dragging
dragSource.startDrag (event, dragIcon, trans, this);
else
System.out.println( "nothing was selected");
* a drop has occurred
public void drop (DropTargetDropEvent event)
try
Transferable transferable = event.getTransferable();
// we accept only Strings
if (isTransferableSupported (transferable))
event.acceptDrop(event.getDropAction());
handleDrop(transferable, event);
event.getDropTargetContext().dropComplete(true);
else
event.rejectDrop();
catch (Exception e)
e.printStackTrace();
System.err.println( "Drop Exception" + e.getMessage());
event.rejectDrop();
//DragSourceListener interfaces
* is invoked when you are dragging over the DropSite
public void dragEnter (DropTargetDragEvent event)
// debug messages for diagnostics
//System.out.println( "dragEnter");
int action = event.getDropAction();
event.acceptDrag (action);
* is invoked when you are exit the DropSite without dropping
public void dragExit (DropTargetEvent event)
//System.out.println( "dragExit");
* is invoked when a drag operation is going on
public void dragOver (DropTargetDragEvent event)
//System.out.println( "dragOver");
* is invoked if the use modifies the current drop gesture
public void dropActionChanged ( DropTargetDragEvent event )
//gets the cursor to start drag
protected Cursor getDragCursor( DragGestureEvent event)
if (event.getDragAction() == DnDConstants.ACTION_MOVE)
return DragSource.DefaultMoveDrop;
if (event.getDragAction() == DnDConstants.ACTION_COPY_OR_MOVE)
return DragSource.DefaultCopyDrop;
else
return Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR);
* this message goes to DragSourceListener, informing it that the dragging
* has ended
public void dragDropEnd (DragSourceDropEvent event) {
if ( event.getDropSuccess())
dropSuccess(event);
else
dropFailed(event);
* this message goes to DragSourceListener, informing it that the dragging
* has entered the DropSite
public void dragEnter (DragSourceDragEvent event)
//System.out.println( " dragEnter");
* this message goes to DragSourceListener, informing it that the dragging
* has exited the DropSite
public void dragExit (DragSourceEvent event)
//System.out.println( "dragExit");
* this message goes to DragSourceListener, informing it that the dragging is currently
* ocurring over the DropSite
public void dragOver (DragSourceDragEvent event)
//System.out.println( "dragExit");
* is invoked when the user changes the dropAction
public void dropActionChanged ( DragSourceDragEvent event)
//System.out.println( "dropActionChanged");
public class TransferableDataItem extends DefaultMutableTreeNode implements Transferable
final static int DATA_ITEM = 0;
final static int STRING = 1;
final static int PLAIN_TEXT = 2;
//final public static DataFlavor DEFAULT_MUTABLE_DATAITEM_FLAVOR =
// new DataFlavor(DefaultMutableTreeNode.class, "Default Mutable Data Item");
final public static DataFlavor DEFAULT_MUTABLE_DATAITEM_FLAVOR =
new DataFlavor(IconNode.class, "Default Mutable Data Item");
static DataFlavor flavors[] = {DEFAULT_MUTABLE_DATAITEM_FLAVOR, DataFlavor.stringFlavor, DataFlavor.plainTextFlavor};
private Object data;
public TransferableDataItem()
public TransferableDataItem(Object data)
this.data = data;
public DataFlavor[] getTransferDataFlavors()
return flavors;
public Object getTransferData(DataFlavor flavor)
throws UnsupportedFlavorException, IOException
Object returnObject;
if (flavor.equals(flavors[DATA_ITEM]))
returnObject = data;
else if (flavor.equals(flavors[STRING]))
returnObject = data.toString();
else if (flavor.equals(flavors[PLAIN_TEXT]))
returnObject = new ByteArrayInputStream(data.toString().getBytes());
else
throw new UnsupportedFlavorException(flavor);
return returnObject;
public boolean isDataFlavorSupported(DataFlavor flavor)
boolean returnValue = false;
for (int i=0, n=flavors.length; i<n; i++) {
if (flavor.equals(flavors[i]))
returnValue = true;
break;
return returnValue;
public class DNDList extends JList
DropTarget dropTarget;
public DNDList()
DNDListHandler dndHandler = new DNDListHandler(this);
setModel(new DefaultListModel());
//private void addElement(Point location, Object element)
private void addElement(Point location, IconNode element)
int index = locationToIndex(location);
// If index not found, add at end, otherwise add one beyond position
if (index == -1) {
index = getModel().getSize();
else
index++;
((DefaultListModel)getModel()).add(index, element);
public class DNDListHandler extends DnDHandler
TransferableDataItem transDataItem = new TransferableDataItem();
public DNDListHandler(Component dndComponent)
super(dndComponent);
public DataFlavor[] getSupportedDataFlavors()
return transDataItem.getTransferDataFlavors();
public DataFlavor[] getTransferDataFlavors()
return transDataItem.getTransferDataFlavors();
* Gets the data from the selected object being dragged
* @return node Node being dragged
public Transferable getTransferable()
Object selectedItem = getSelectedValue();
System.out.println("Selected Value is " + selectedItem);
TransferableDataItem item = new TransferableDataItem(selectedItem);
return(item);
* Handles the drop of the component after the drag is complete
* @param transferable Object being dropped
* @param event drop event information
public void handleDrop(Transferable transferable, DropTargetDropEvent event) throws Exception
Transferable tr = event.getTransferable();
Point location = event.getLocation();
if (tr.isDataFlavorSupported(TransferableDataItem.DEFAULT_MUTABLE_DATAITEM_FLAVOR))
//event.acceptDrop (DnDConstants.ACTION_COPY_OR_MOVE);
// Object userObject = tr.getTransferData(TransferableDataItem.DEFAULT_MUTABLE_DATAITEM_FLAVOR);
IconNode userObject = (IconNode)tr.getTransferData(TransferableDataItem.DEFAULT_MUTABLE_DATAITEM_FLAVOR);
addElement(location, userObject);
//dropTargetDropEvent.getDropTargetContext().dropComplete(true);
else
System.err.println ("Rejected");
event.rejectDrop();

Answer 1

I think your problem come from this method :
if (tr.isDataFlavorSupported(TransferableDataItem.DEFAULT_MUTABLE_DATAITEM_FLAVOR))
   System.out.println("Got transfered data");
   Object userObject = tr.getTransferData(TransferableDataItem.DEFAULT_MUTABLE_DATAITEM_FLAVOR);
//DefaultMutableTreeNode node = (DefaultMutableTreeNode)path.getLastPathComponent();
   IconNode node = (IconNode)path.getLastPathComponent();
   IconNode newNode = new IconNode(userObject);
   DefaultTreeModel model = (DefaultTreeModel)getModel();
   model.insertNodeInto(newNode, node, 0);
...You should write :
if (tr.isDataFlavorSupported(TransferableDataItem.DEFAULT_MUTABLE_DATAITEM_FLAVOR))
   IconNode node = (IconNode)tr.getTransferData(TransferableDataItem.DEFAULT_MUTABLE_DATAITEM_FLAVOR);
   IconNode node = (IconNode)path.getLastPathComponent();
   IconNode newNode = new IconNode(node);
   DefaultTreeModel model = (DefaultTreeModel)getModel();
   model.insertNodeInto(newNode, node, 0);
...and create a construcor for IconNode :
public IconNode(IconNode node) {
   super(node.getUserObject, node.getAllowsChildren());
   icon = node.icon;
}When you use IconNode newNode = new IconNode(userObject), the icon is null (see your constructor).
If I can say something, you should simplify your code : you can do the same thing dividing the size of your code by five (at less).
Denis