FULL PRODUCT VERSION :
java version "1.6.0_05"
Java(TM) SE Runtime Environment (build 1.6.0_05-b13)
Java HotSpot(TM) Client VM (build 10.0-b19, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [Version 5.1.2600]

A DESCRIPTION OF THE PROBLEM :
When dragging a DefaultMutableTreeNode that implements Transferable inside of a JTree (local), the Transferable retrieved inside of importData, is not the "same" object that was exported with createTransferable.


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Using the code posted below, drag the JTree node with name "choco" onto itself.


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
I would expect that the Transferable containers be the same. The one created during export, should be the one given during import.
ACTUAL -
Note the output, the hashcodes on the Transferables do not verify (though as side note, the contents of their getUserObject functions do).

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreePath;
import java.io.*;


/**
 * Dragging and dropping chocolate milk onto default category should remove
 * the node from its parent, but it doesn't. *puzzle*
 */
public class Test extends JFrame{
private static final long serialVersionUID = 1L;

private static Category root;

static{
root = new Category( "root category" );

Category milk = new Category( "milk" );
Category cmilk = new Category( "chocolate milk" );
Category choco = new Category( "choco" );

String test = "ATEST";

choco.setUserObject( test );

milk.add( cmilk );
root.add( milk );
root.add( choco );
}


public static void main( String args[]) throws Exception {
JFrame f = new JFrame();
f.setSize( 400, 400 );
f.getContentPane().add( new JScrollPane( new TestTree() ) );
f.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
f.setVisible( true );
}


/**
* Our tree
*/
private static final class TestTree extends JTree {
private static final long serialVersionUID = 1L;

private DefaultTreeModel model;
private TreePath selectedPath;
private Category originalTransferable;

public TestTree(){
model = new DefaultTreeModel( root );
setModel( model );
setDragEnabled( true );
setTransferHandler( new TreeNodeTransferHandler() );
setDropMode( DropMode.ON_OR_INSERT );

addTreeSelectionListener( new TreeSelectionListener() {
public void valueChanged( TreeSelectionEvent e ){
TreePath path = e.getNewLeadSelectionPath();

if( path != null ){
selectedPath = path;
}
}
});
}

private class TreeNodeTransferHandler extends TransferHandler {
private static final long serialVersionUID = 1L;


public boolean importData( TransferSupport info ) {
if( !canImport(info) )
return false;

try{
// fetch the drop location
JTree.DropLocation dl = (JTree.DropLocation)info.getDropLocation();
TreePath path = dl.getPath();
Category dragged = (Category)info.getTransferable().getTransferData( Category.categoryFlavor );
Category target = (Category)path.getLastPathComponent();

System.out.println(
" --> Original transferable hashcode : " +
originalTransferable.hashCode() +
"\n --> Actual transferable hashcode : " +
((Category)info.getTransferable().getTransferData( Category.categoryFlavor )).hashCode()
);

System.out.println(
" --> Original transferable hashcode : " +
originalTransferable.getUserObject().hashCode() +
"\n --> Actual transferable hashcode : " +
((Category)info.getTransferable().getTransferData( Category.categoryFlavor )).getUserObject().hashCode()
);


System.out.println( "droppped " + dragged + " onto " + target );
((Category)dragged.getParent()).removeSubcategory( dragged, model );

return true;
}
catch( Exception x ){
x.printStackTrace();
}
return false;

}

public int getSourceActions( JComponent c ){
return TransferHandler.MOVE;
}

@Override
protected Transferable createTransferable( JComponent c ){
if( c.equals( TestTree.this ) ){
if( selectedPath != null && !((Category)selectedPath.getLastPathComponent()).isRoot() ){
originalTransferable = (Category)selectedPath.getLastPathComponent();
return originalTransferable;
}
}
return null;
}

public boolean canImport( TransferSupport info ){
if( !info.isDrop() )
return false;

if( !info.isDataFlavorSupported( Category.categoryFlavor ) )
return false;

JTree.DropLocation dl = (JTree.DropLocation)info.getDropLocation();

if( dl == null || dl.getPath() == null )
return false;

Object transferdata = null;
try{
transferdata = info.getTransferable().getTransferData( Category.categoryFlavor );
}
catch( Exception e ){
e.printStackTrace();
}


// can't drop a null node, nor can a node be dropped onto itself
return dl.getPath().getLastPathComponent() != null
&& dl.getPath().getLastPathComponent() != transferdata;
}

}
}


/**
* Dummy node object
*/
private static final class Category extends DefaultMutableTreeNode implements Transferable{
private static final long serialVersionUID = 1L;
public static final DataFlavor categoryFlavor = new DataFlavor( Category.class, "Category" );
public static final DataFlavor[] transferDataFlavors = new DataFlavor[]{ categoryFlavor };

private String title;

public Category( String t ){
title = t;
}

@Override
public String toString() {
return title;
}

@Override
public Object getTransferData(DataFlavor flavor)
throws UnsupportedFlavorException, IOException {
if( flavor.equals( categoryFlavor ) )
return this;

return null;
}

@Override
public DataFlavor[] getTransferDataFlavors() {
return transferDataFlavors;
}

@Override
public boolean isDataFlavorSupported(DataFlavor flavor) {
return flavor.equals( categoryFlavor );
}

/**
* Remove a child category from this category
* @param n
*/
public void removeSubcategory( final Category n, final DefaultTreeModel model ){
int[] childIndex = new int[1];
Object[] removedArray = new Object[1];
childIndex[0] = getIndex( n );
removedArray[0] = n;
remove( n );
model.nodesWereRemoved( this, childIndex, removedArray );
}
}
}

---------- END SOURCE ----------