Multiple Selection in JTree, Drag & Drop

Question

Hi everybody,
I was wondering if anyone knows how to implement Multiple Selection Drag and Drop in a JTree. I know that there used to be a bug in jdk 1.3 that would allow it, but I suspect 1.4 fixed that. I've implemented Single-selection just fine, but I'm trying do Multiple selection by drawing a selection rectangle and selecting whatever nodes are contained within that rectangle. So far I've implemented it by adding a MouseListener to my JTree, finding which rows are intersected by the rectangle and calling addSelectionRow() to add the TreePaths.
Is there an easier way to multiple selection now that the bug of 1.3(I hope) has been fixed?

Answer 1

Okay, now I've implemented the changes in the DragGestureListener, DragSourceListener and DragTargetListener in order to make Multiple Selection possible, however I want to select multiple items the same way Windows Explorer does by:
1. pressing the left-mouse button & dragging a "selection" rectangle which selects all the nodes contained within that rectangle.
2. then drag and drop is accomplished by pressing one of the selected nodes and dragging it (along with it's other selected siblings) to the destination.
In order to accomplish this I added into the Constructor of my JTree extending class this code:
public class MyTree extends JTree {
private static int x1, y1, x2, y2;
public MyTree(DefaultMutableTreeNode rootNode){
// Other Constructor stuff...
this.addMouseMotionListener( new MouseMotionListener() {
public void mouseDragged(MouseEvent e) {  
x2 = e.getX();
y2 = e.getY();
repaint();
public void mouseMoved(MouseEvent e){     }
this.addMouseListener(new MouseAdapter(){
boolean dontRelease = false;
public void mousePressed( MouseEvent e){
x1 = e.getX();
y1 = e.getY();
int[] rows = getSelectionRows();
boolean dropSel = true;
if (rows != null){
for (int i = 0; i < rows.length; i++){
Rectangle rect3 = getRowBounds(i);
if (rect3.contains(x1, y1)){
dropSel = false;
dontRelease = true;
if (dropSel){
for (int i =0; i < rows.length; i++)
removeSelectionRow(i);
public void mouseReleased( MouseEvent e){
x2 = e.getX();
y2 = e.getY();
repaint();
if (dontRelease == false) {
Rectangle rect2 = new Rectangle(Math.min(x1, x2),
Math.min(y1, y2), Math.abs(x1-x2), Math.abs(y1-y2));
int rowCount = getRowCount();
for (int i = 1; i < rowCount; i++) {
Rectangle rect3 = getRowBounds(i);
if ((rect2.contains(rect3)) || (rect2.intersects(rect3))){
addSelectionRow(i);
dontRelease = false;
repaint();
The idea was that for every press of the mouse the 1st set of x,y coords. are taken to be the starting corner of the "selection" rectangle, and every point passed over while dragging would be the ending corner of the rectangle (so that in paintComponents, you could actually draw the rectangle).
Once the mouse is released it will check to see if the selection rectangle had contained or intersected any of the rows (basically I find how many rows are being shown in the tree and go through each one to see if there is intersection/containment). If a row is contained it becomes selected.
The remaining code in MousePressed is used if node(s) were previously selected it goes through and checks to see if this mouse press is at the location of one of the previous selected nodes - if it is then you can drag that node along with all of its siblings to their destination. However if your mouse press is not on one of the selected nodes - all the nodes should be deselected (like in explorer if you press away from your selection, you lose it). If you select and begin to drag your selection dontRelease should not allow the creation of another "selection" rectangle to occur during the drag-n-drop process.
-That's how I thought this code should work. Unfortunately as it does most of these things it does not correctly implement rule #2 of Windows Explorer (2. only by dragging one of the selected nodes can you drag them, otherwise you lose them)...currently as long as something is selected you can do a mouse press and drag from another location and as long as that location does not contain a node (like it is a blank area in the JTree), you can drag everything to the destination from when you start dragging.
I looked around and saw that perhaps it is due to the BasicTreeUI interferring with it's own MouseInputHandler() so I wrote MyTreeUI that extends BasicTreeUI, basically changing only the MouseInputHandler to contain the functions above, and I blocked /**/ those functions from my MyTree Constructor.
Then in my main class (the one of instantiate my MyTree and my DefaultMutableTreeNodes), I wrote:
try
String myTreeUI = "MyTreeUI";
UIManager.put( "MyTreeUI", myTreeUI );
UIManager.put( myTreeUI,
Class.forName( myTreeUI ) );
} catch( ClassNotFoundException cnfe ) {
System.err.println( "My Tree UI class not found" );
System.err.println( cnfe );
...thinking that that would be all I needed in order to set MyTreeUI as the JTree's UI, LooknFeel, etc. and although I did not get that ClassNotFoundException when running the program, it did not have any of the functionality that I had written ( I even wrote a System.out.println() in my MousePressed() function in MyTreeUI so that it would let me know that it is working and it never appeared). It was as if the MyTreeUI was not loaded or attached to the JTree. I also called:
System.out.println("this is UI: " + jTree1.getUIClassID() );
to see which UI my MyTree instantiate was using and it would printout TreeUI, not MyTreeUI. So I'm wondering what it is I'm doing wrong, I think I am very close to having this thing working but I want to know if anybody here would be able to let me know what I'm doing wrong or what would be the best way to go about implementing this Windows Explorer Multiple Selection JTree.
Sorry for the long-winded explanation,
-Meddev24.