"class Junk extends Hashtable .. implements MutableTreeNode" seems flakey

Question

If I add 3 child nodes to one root and then use DefaultTreeModel(root) in a JTree using this very basic implementation of MutableTreeNode, I can see all three children. Just by merely adding "extends Hashtable.." only the last child shows & blank space is shown in place of the other two (the lines are missing for them as well). Can anybody explain this? For now, I no longer am extending Hashtable - after several hours of figuring out what my problem was.
Regards,
Monty
package temp;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Vector;
import javax.swing.tree.MutableTreeNode;
import javax.swing.tree.TreeNode;
public class Node  implements MutableTreeNode {
     final Vector<Node> v = new Vector<Node>();
     final String name;
     Node parent;
     Node(String n) {
          name = n;
     public void insert(MutableTreeNode child, int index) {
          // TODO Auto-generated method stub
     public void remove(int index) {
          // TODO Auto-generated method stub
     public void remove(MutableTreeNode node) {
          // TODO Auto-generated method stub
     public void removeFromParent() {
          // TODO Auto-generated method stub
     public void setParent(MutableTreeNode newParent) {
          parent = (Node) newParent;
     public void setUserObject(Object object) {
     public Enumeration children() {
          return v.elements();
     public String toString() {
          return name;
     public boolean getAllowsChildren() {
          return true;
     public TreeNode getChildAt(int childIndex) {
          // TODO Auto-generated method stub
          return v.get(childIndex);
     public int getChildCount() {
          return v.size();
     public int getIndex(TreeNode node) {
          return v.indexOf(node);
     public TreeNode getParent() {
          return parent;
     public boolean isLeaf() {
          return v.isEmpty();
}

Answer 1

Define equals() and hashCode() methods appropriately in your custom tree node class otherwise the methods from Hashtable, which would be empty in your tested code, are used resulting a weird JTree object. See the API documentation for the TreeModel interface for the issue.
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