New Jtree node not displaying

Question

I have created a Jtree with some default elements. Later on I add new ones with the: treeModel.insertNodeInto() method. However the new node is not displayed. If I colapse and expand the tree it's still not displayed. Is there anything I need to do to tell the tree to refresh itself.

Answer 1

Here are some more details that might help isolate this refresh problem. I've got a custom JPanel that displays a JTree. The root of JTree has 2 children: A, and B. You can dynamically add a Foler to A, where Folder implements TreeNode. You can drag elements from the tree rooted at B to a Batch. I've subclassed JTree to handle the drag and drop.
public class Folder implements MutableTreeNode {
public class MyPanel extends JPanel {
    private DefaultMutableTreeNode root, A, B;
    private MyTree tree;
    public MyPanel() {
        root = new DefaultMutableTreeNode();
        A = new DefaultMutableTreeNode("A");
        B = new DefaultMutableTreeNode("B");
        root.add(A);
        root.add(B);
        tree = new MyTree(root);
    // this method refreshes the tree correctly!!!
    public void addFolder(Folder f) {
        A.insert(f, A.getChildCount());
        // let the model know that the node was inserted
        DefaultTreeModel model = (DefaultTreeModel)tree.getModel();
        model.nodesWereInserted(A, new int[] {A.getChildCount() - 1});
        tree.makeVisible(new TreePath(new Object[] {root, A, f}));
public class MyTree extends JTree
implements DropTargetListener, DragSourceListener, DragGestureListener {
    public MyTree(DefaultMutableTreeNode root) {
        super(root);
    // method that handles the drop
    // DnDNode is a subclass of MutableTreeNode that implements Transferable
    // this method does _not_ update the UI correctly
    public void drop(DropTargetDropEvent dtde) {
        try {
            Transferable t = dtde.getTransferable();
            if ( t.isDataFlavorSupported(...) ) {
                Point p = dtde.getLocation();
                TreePath path = getPathForLocation(p.x, p.y);
                if (path != null && path.getLastPathComponent() instanceof Folder) {
                    dtde.acceptDrop(DnDConstants.ACTION_COPY);
                    Folder parent = (Folder)path.getLastPathComponent();
                    DnDNode child = (DnDNode)t.getTransferData(...);
                    parent.insert(child, parent.getChildCount());
                    model.nodesWereInserted(parent, new int[] {parent.getChildCount() - 1});
                    makeVisible(path.pathByAddingChild(child));
                    dtde.getDropTargetContext().dropComplete(true);
                else dtde.rejectDrop();
            else dtde.rejectDrop();
        catch(Exception ioe) {... }
}To sum up, the UI is correctly refreshed when I call the addFolder() method in the class MyPanel. The UI does not refresh correctly after the drop() method in the MyTree class. Even though the same methods are used for both insertions.