TreeStructureChanged vs treeNodesChanged

Question

Hi all,
I'm working with tree models to show to the user a tree data structure. The idea is simple: I've got a few Person objects, each person has a few properties (in this example the name and the surname) and a list of Skill objects, each with a couple of properties. I want to show the data in a tree using a model.
I worked on the thread http://forum.java.sun.com/thread.jspa?threadID=5242097 and found that I had to inform the tree about changes. This rises a new problem (the one of this question): I found that only if I call listener.treeStructureChanged(event); I can see the node changing, but a treeNodesChanged instead should be more appropriate, since it does not forces loading the whole tree. Anybody can help me understanding why a call to treeNodesChanged does not work?
import java.awt.Component;
import java.util.*;
import javax.swing.*;
import javax.swing.event.TreeModelEvent;
import javax.swing.event.TreeModelListener;
import javax.swing.tree.*;
class Person{
    String name = null;
    String surname = null;
    int id = 0;
    private List<Skill> skills = new LinkedList<Skill>();
    private static int counter = 1;
    Person(String name, String surname){
     this.name = name;
     this.surname = surname;
     id = counter++;
    public String getName() {
        return name;
    public void setName(String name) {
        this.name = name;
    public String getSurname() {
        return surname;
    public void setSurname(String surname) {
        this.surname = surname;
    public String toString(){
     return "Person number " + id;
    public void addSkill(Skill skill){
     this.skills.add(skill);
    public List<Skill> getSkills(){
     return this.skills;
    public void removeSkill(Skill sk){
     this.skills.remove(sk);
class Skill{
    private int skillId = 0;
    private String skillDescription = null;
    public Skill(int id, String description){
     super();
     this.skillId = id;
     this.skillDescription = description;
    public String toString(){
     return "Skill number " + this.skillId + " {" + this.skillDescription + "}";
     * Returns the value of the field <code>skillDescription</code>.
     * @return the skillDescription
    public String getSkillDescription() {
        return skillDescription;
     * Allows the set-up of the field <code>skillDescription</code> to the specified value.
     * @param skillDescription the <code>skillDescription</code> value to set
    public void setSkillDescription(String skillDescription) {
        this.skillDescription = skillDescription;
     * Returns the value of the field <code>skillId</code>.
     * @return the skillId
    public int getSkillId() {
        return skillId;
     * Allows the set-up of the field <code>skillId</code> to the specified value.
     * @param skillId the <code>skillId</code> value to set
    public void setSkillId(int skillId) {
        this.skillId = skillId;
class PersonModel implements TreeModel{
     private List<Person> people = null;
     private String root = "## HERE THE ROOT ##";
     private LinkedList<TreeModelListener> listeners = new LinkedList<TreeModelListener>();
     public PersonModel(List<Person> people){
          super();
          this.people = people;
     @Override
     public void addTreeModelListener(TreeModelListener l) {
          this.listeners.add(l);
     @Override
     public Object getChild(Object parent, int index) {
          System.out.println("getChild called with " + parent + " - " + index);
          Object ret = null;
          if( parent instanceof Person ){
               Person parentPerson = (Person) parent;
               // index = 1 => name
               switch(index){
               case 0:     ret = parentPerson.getName(); break;
               case 1: ret = parentPerson.getSurname(); break;
               default: ret = parentPerson.getSkills().get(index - 2); break;
               System.out.println("\n\treturning " + ret);
               return ret;
          else
          if( parent instanceof Skill ){
               Skill parentSkill = (Skill) parent;
               switch(index){
               case 0: ret = parentSkill.getSkillId(); break;
               case 1: ret = parentSkill.getSkillDescription(); break;
               default: ret = "SKILL WHAT?"; break;
               System.out.println("\n\t returning " + ret);
               return ret;
          else
          if( parent.equals(root)){
               ret = this.people.get(index);
               System.out.println("\n\t returning " + ret);
               return ret;
          else
               return "NOT FOUND IN THE MODEL";
     @Override
     public int getChildCount(Object parent) {
          System.out.println("getChildCount called " + parent);
          if( parent instanceof Person )
               return 2 + ((Person)parent).getSkills().size();
          else
          if( parent instanceof Skill )
               return 2;
          else
          if( parent.equals(root))
               return this.people.size();
          else
               return -1;
     @Override
     public int getIndexOfChild(Object parent, Object child) {
          System.out.println("getIndexOfChild called " + parent + " - " + child);
          if( parent instanceof Person ){
               Person parentPerson = (Person) parent;
               if( child instanceof Skill )
                    return parentPerson.getSkills().indexOf(child);
               else
               if( child instanceof String ){
                    String childString = (String) child;
                    if( childString.equals( parentPerson.getName() )){
                         System.out.println("\n\tfound child at index 1");
                         return 1;
                    else{
                         System.out.println("\n\t found child at index 2");
                         return 2;
          else
          if( parent instanceof Skill ){
               Skill parentSkill = (Skill) parent;
               String childString = (String) child;
               if( childString.equals( parentSkill.getSkillId())){
                    System.out.println("\n\tfound child at index 1");
                    return 1;
               else{
                    System.out.println("\n\tfound child at index 2");
                    return 2;
          else
          if( parent.equals( this.root )){
               System.out.println("\n\treturning person " + this.people.indexOf(child));
               return this.people.indexOf(child);
               return -1;
     @Override
     public Object getRoot() {
          return this.root;
     @Override
     public boolean isLeaf(Object node) {
          System.out.println("isLeaf called " + node);
          if( node instanceof String && node.equals(this.root) == false){
               System.out.println("\n\tthis is a leaf");
               return true;
          else{
               System.out.println("\n\tthis is not a leaf");
               return false;
     @Override
     public void removeTreeModelListener(TreeModelListener l) {
          // TODO Auto-generated method stub
     @Override
     public void valueForPathChanged(TreePath path, Object newValue) {
          // TODO Auto-generated method stub
     protected void fireTreeStructureChanged(Person p){
          TreeModelEvent event = new TreeModelEvent(this, new Object[]{ this.getRoot(), p});
          for(TreeModelListener listener : this.listeners){
               System.out.println("Notifico evento di ristrutturazione a " + listener);
               listener.treeStructureChanged(event);
public class PersonTreeTest extends JFrame {
     private JTree tree = null;
     private TreeModel model = null;
     public PersonTreeTest(List<Person> people){
          super("Tree Test");
          this.model = new PersonModel(people);
          this.tree = new JTree(model);
          this.add(new JScrollPane(this.tree) );
          this.setSize(300,300);
          this.setVisible(true);
     public static void main(String argv[]) throws Exception{
          List<Person> people = new LinkedList<Person>();
          for(int i=0;i<10000;i++){
               Person p = new Person("PERSON" + i,"---");
               people.add(p);
          Person p1 = new Person("Luca", "Ferrari");
          Skill s1 = new Skill(1,"A FIRST SKILL");
          Skill s2 = new Skill(2, "A SECOND SKILL");
          Skill s3 = new Skill(3, "A THIRD SKILL");
          p1.addSkill(s1);
          p1.addSkill(s2);
          Person p2 = new Person("Sam","Ferrari");
          p2.addSkill(s3);
          people.add(p1);
          people.add(p2);
          PersonTreeTest test = new PersonTreeTest(people);
          Thread.currentThread().sleep(5000);
          System.out.println("Changing a node");
          p1.setName("LLUUCCAA");
          PersonModel model = (PersonModel) test.tree.getModel();
          model.fireTreeStructureChanged(p1);
}

Answer 1

Hi,
I've tried also to notify the tree of a node changes specifying the root node (and no one child path), but it still does not work:
protected void fireTreeStructureChanged(Person p){
                TreeModelEvent event = new TreeModelEvent(this, new Object[]{ this.getRoot()});
                for(TreeModelListener listener : this.listeners){
                        listener.treeNodesChanged(event);
        }The javadoc for the treeNodesChanged says that: The node(s) have not changed locations in the tree or altered their children arrays, but other attributes have changed and may affect presentation. Example: the name of a file has changed, but it is in the same location in the file system.
So it should be correct, in my example, to call the treeNodesChanged, but it is not working. Any idea?
Thanks,
Luca