GetTreeCellRendererComponent(): get path to value without using row-arg?

Question

I'm using a JTree to display hierarchical data which include cyclic dependencies (i.e. an item may be its own ancestor).
If a node shows up for the second time in a hierarchical tree path, I put a stop to further expansion (using the getPath() of a TreeExpansionEvent in a TreeWillExpandListener), and I give the node a special display (using a tree-cell renderer with a custom implementation of getTreeCellRendererComponent()). The implementation uses tree.getPathForRow(row) to get the path by which can be detected if a node is cyclic, but this does not always work: sometimes tree.getPathForRow(row).getLastPathComponent() corresponds to the value-object given as argument to getTreeCellRendererComponent(), but sometimes it does not.
The example below shows the difference (switch the lines marked "Not OK" by the line marked "OK"; to keep it simple, I left the cyclic dependencies out).
Checking the swing source files reveals that if getTreeCellRendererComponent() is called by paintRow() in BasicTreeUI, value and row correspond. But if getTreeCellRendererComponent() is called by getNodeDimensions() in one of the LayoutCache-classes, the given value-object does not correspond to the object at the given tree-row. Somewhere I read that getNodeDimensions() is called to determine preferred sizes of nodes before they are shown for the first time. If that's the case, it is logical that value and row do not correspond, although I would have liked to get a hint, e.g. a row value of -1.
To detect a cyclic node, I need a treepath, but the row-argument is unreliable. Is there another way to determine the path corresponding to the value-object passed to getTreeCellRendererComponent(), so without having to use the row-argument?
* treeUpdate.java
package treeupdate;
import java.awt.Component;
import java.awt.Dimension;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JLabel;
import javax.swing.JTree;
import javax.swing.event.EventListenerList;
import javax.swing.event.TreeModelListener;
import javax.swing.tree.TreeCellRenderer;
import javax.swing.tree.TreeModel;
import javax.swing.tree.TreePath;
public class treeUpdate extends javax.swing.JFrame {
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTree jTree1;
    private ItemInHierarchy root = null;
    private SimpleTreeModel htm = new SimpleTreeModel();
    private SimpleTreeCellRenderer htcr = new SimpleTreeCellRenderer();
    public treeUpdate() {
        initComponents();
        generateHierarchy();
        jTree1.setModel(htm);
        jTree1.setCellRenderer(htcr);
    // init
    private void initComponents() {
        setTitle("row-value correspondence");
        setSize(new Dimension(300,500));
        jScrollPane1 = new javax.swing.JScrollPane();
        jTree1 = new javax.swing.JTree();
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        jScrollPane1.setViewportView(jTree1);
        add(jScrollPane1);
    // generate data
    private void generateHierarchy() {
        root = new ItemInHierarchy("Joverra");
        ItemInHierarchy c1 = new ItemInHierarchy("Kondat Kalbendate");
        c1.children.add(new ItemInHierarchy("Linovar Welchessante Somtanessia"));
        c1.children.add(new ItemInHierarchy("Muzarra Frontiminoi Wioppallae"));
        c1.children.add(new ItemInHierarchy("Niobitia Fyttichiokla Quantianou"));
        root.children.add(c1);
        ItemInHierarchy c2 = new ItemInHierarchy("Orud Kalbene");
        c2.children.add(new ItemInHierarchy("Pascalite Welchessante Somtanessia"));
        c2.children.add(new ItemInHierarchy("Quinnime Frontiminoi Wioppallae"));
        c2.children.add(new ItemInHierarchy("Ruttinovi Fyttichiokla Quantianou"));
        root.children.add(c2);
        ItemInHierarchy c3 = new ItemInHierarchy("Si Kae");
        c3.children.add(new ItemInHierarchy("Tonniate Welchessante Somtanessia"));
        c3.children.add(new ItemInHierarchy("Uvverten Frontiminoi Wioppallae"));
        c3.children.add(new ItemInHierarchy("Vlioppala Fyttichiokla Quantianou"));
        root.children.add(c3);
     * Tree model
    private class SimpleTreeModel implements TreeModel {
        protected EventListenerList listenerList = new EventListenerList();
        public Object getRoot() {
            return root;
        public Object getChild(Object parent, int index) {
            ItemInHierarchy i = (ItemInHierarchy)parent;
            return i.children.get(index);
        public int getChildCount(Object parent) {
            ItemInHierarchy i = (ItemInHierarchy)parent;
            return i.children.size();
        public boolean isLeaf(Object node) {
            ItemInHierarchy i = (ItemInHierarchy)node;
            return i.children.size()==0;
        public void valueForPathChanged(TreePath path, Object newValue) {
            // do nothing
        public int getIndexOfChild(Object parent, Object child) {
            ItemInHierarchy i = (ItemInHierarchy)parent;
            for (int k = 0; k < i.children.size(); k++) {
                if (i.children.get(k).equals((ItemInHierarchy)child)) {
                    return k;
            return -1;
        public void addTreeModelListener(TreeModelListener l) {
            listenerList.add(TreeModelListener.class, l);
        public void removeTreeModelListener(TreeModelListener l) {
            listenerList.remove(TreeModelListener.class, l);
     * Cell renderer
    private class SimpleTreeCellRenderer extends JLabel implements TreeCellRenderer {
        public SimpleTreeCellRenderer() {
            setOpaque(true);
        public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row, boolean hasFocus) {
            // OK
            // setText(value.toString());
            // Not OK
            TreePath tp = tree.getPathForRow(row);
            if (tp!=null) {
                setText(tp.getLastPathComponent().toString());
            } else {
                setText("?");
            return this;
     * Item in hierarchy
    public class ItemInHierarchy {
        public List<ItemInHierarchy> children = new ArrayList<ItemInHierarchy>();
        public String name;
        public ItemInHierarchy() {
        public ItemInHierarchy(String name) {
            this.name = name;
        @Override
        public String toString() {
            return name;
    // main
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new treeUpdate().setVisible(true);
}

Answer 1

Kleopatra wrote:
The only general way to hack-around, as far as I remember, is to force the VariableSomething out of the way and make a FixedSomething takes it place. No api, but you can reach that by doing both:
- tree.setLargeModel(true)
- tree.setRowHeight(somevalueabovezero)
Your memory's fine. I ran a short test, this seems to make row- and value-arguments correspond to each other consistently.
Kleopatra wrote:
... before expanding a node it calls the renderer with the row set to the the row following the row of the node to expand (same for all children)...I suspected something like this, and it opens up a way to solve my question, but it seemed like a too shallow basis for coding. I'm satisfied with fixed row heights, so I'll stick to your suggestion above, and I'll include a short equality test in getTreeCellRendererComponent(), just to make sure:
value.equals(tree.getPathForRow(row).getLastPathComponent())Thanks for the help - Jan