How to change TreeModel into DefaultTreeModel?

Question

//This is my own TreeModel class:
package xj.guieditor;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.*;
import org.w3c.dom.*;
import java.io.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
* <p>Title: </p>
* <p>Description: </p>
* <p>Copyright: Copyright (c) 2002</p>
* <p>Company: </p>
* @author unascribed
* @version 1.0
public class MyTreeModel implements TreeModel {
private Document root;
public MyTreeModel(Document doc){
root = doc;
public Object getRoot() {
return root;
public Object getChild(Object parent, int index) {
return ((Node)parent).getChildNodes().item(index);
public int getChildCount(Object parent) {
return ((Node)parent).getChildNodes().getLength();
public boolean isLeaf(Object node) {
return ((Node)node).getChildNodes().getLength() == 0;
public void valueForPathChanged(TreePath path, Object newValue) {  }
public int getIndexOfChild(Object parent, Object child) {
NodeList nl = ((Node)parent).getChildNodes();
for(int i=0; i< nl.getLength(); i++)
if( ((Node)child).equals(nl.item(i)) )
return i;
return -1;
public void addTreeModelListener(TreeModelListener l) {  }
public void removeTreeModelListener(TreeModelListener l) {  }
//And in my main file,I parse the xml file like this:
DOMParser parser = new DOMParser();
String uri = filename;
try{
parser.setIncludeIgnorableWhitespace(true);
this.setTitle("The current file is: " + uri);
parser.parse(uri);
Document doc = parser.getDocument();
doc.normalize();
removeWhiteSpaceNodes(doc.getDocumentElement());
model = new MyTreeModel(doc);
tree = new JTree(model);
//And now I want to do some add and remove actions with the xml tree nodes.I want to use the DefaultTreeModel class ,how can I do?Thank you.

Answer 1

public class MyTreeModel extends DefaultTreeModel {