need help with jTree isNodeAncestor()

[Max Simpson]

isNodeAncestor keeps returning false even though the value I pass in is an an ancestor node... here is what i am doing:

1. read a key from a HashMap and create a new node
2. before adding the new node (child) to the current node (node), I want to make sure that it is not an ancestor (parent or grandparent, etc..) of the current node. To do this I call:

node.isNodeAncestor(child);

But if always returns false.. my guess is that it is because the child node, even though it may be the same as an ancestor, is not the actual ancestor node.

Any idea on how I can make this work?

[Craig Wood]

import java.awt.*;
import java.awt.event.*;
import java.util.Enumeration;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.*;
 
public class NodeTest
{
    JTree tree;
 
    public NodeTest()
    {
        tree = getTree();
        JList list = getList();
        JPanel panel = new JPanel(new GridLayout(0,2));
        panel.add(tree);
        panel.add(list);
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new JScrollPane(panel));
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
    }
 
    private boolean isNodeAncestor(String text)
    {
        TreeSelectionModel model = tree.getSelectionModel();
        if(model.isSelectionEmpty())  // no selection
            return true;
        TreePath path = model.getSelectionPath();
        //System.out.println(path.toString());
 
        // check for siblings of perspective parent node
        TreeNode node = (TreeNode)path.getLastPathComponent();
        if(isNodeSibling(node, text))
            System.out.println("* sibling exists for " + text);
 
        // check nodes back up the path to the root node, bottom to top
        TreePath parentPath = path.getParentPath();
        int n = parentPath.getPathCount();
        DefaultMutableTreeNode nextParent;
        for(int j = n - 1; j >= 0; j--) // check last first
        {
            nextParent = (DefaultMutableTreeNode)parentPath.getPathComponent(j);
            String s = (String)nextParent.getUserObject();
            //System.out.println("nextParent[" + j + "] = " + s);
            if(s.equals(text))
                return true;
        }
        return false;
    }
 
    private boolean isNodeSibling(TreeNode node, String text)
    {
        TreeNode parent = node.getParent();
        DefaultMutableTreeNode child;
        for(int j = 0; j < parent.getChildCount(); j++)
        {
            child = (DefaultMutableTreeNode)parent.getChildAt(j);
            String s = (String)child.getUserObject();
            //System.out.println("child[" + j + "] = " + s);
            if(s.equals(text))
                return true;
        }
        return false;
    }
 
    private JTree getTree()
    {
        String[] birds = {
            // branches |<-- child leaf nodes -->|
            "hawks", "gray", "red-tailed", "rough-legged",
            "falcons", "harrier", "kestrel", "kite", 
            "owls", "barred", "saw-whet", "snowy"
        };
        DefaultMutableTreeNode root = new DefaultMutableTreeNode("birds");
        DefaultMutableTreeNode[] nodes = new DefaultMutableTreeNode[birds.length];
        for(int j = 0; j < nodes.length; j++)
            nodes[j] = new DefaultMutableTreeNode(birds[j]);
        for(int j = 0; j < 9; j += 4)
        {
            root.insert(nodes[j], j % 3);
            for(int k = j + 1; k < j + 4; k++)
                nodes[j].insert(nodes[k], k - j - 1);
        }
        DefaultTreeModel model = new DefaultTreeModel(root);
        JTree tree = new JTree(model);
        tree.getSelectionModel().setSelectionMode(
                                     TreeSelectionModel.SINGLE_TREE_SELECTION);
        return tree;
    }
 
    private JList getList()
    {
        DefaultListModel model = new DefaultListModel();
        DefaultMutableTreeNode root = (DefaultMutableTreeNode)tree.getModel().getRoot();
        Enumeration e = root.preorderEnumeration();
        while(e.hasMoreElements())
        {
            DefaultMutableTreeNode node = (DefaultMutableTreeNode)e.nextElement();
            String s = (String)node.getUserObject();
            model.addElement(s);
        }
        final JList list = new JList(model);
        list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        list.addListSelectionListener(new ListSelectionListener()
        {
            public void valueChanged(ListSelectionEvent e)
            {
                if(!e.getValueIsAdjusting())
                {
                    String item = (String)list.getSelectedValue();
                    String answer = isNodeAncestor(item) ? "" : "not ";
                    System.out.println(item + " is " + answer +
                                       "found in path of selected node");
                }
            }
        });
        return list;
    }
 
    public static void main(String[] args)
    {
        new NodeTest();
    }
}