Runtime dynamic filtering TreeModel

Question

Hello,
Changing a tree during runtime seems to be a problem. I've looked at different threads and now I have the following class which filters a delegated DefaultTreeModel (see SimpleFilteredTreeModel and the corresponding TestFilteredTreeModel classes below). Notice, that the commented lines in the isShown-method do filter out alternaitve objects behind the tree at startup of the application correctly.
I used the following two steps to extend the SimpleFilteredTreeModel to make it refreshing dynamically:
1. Step: ViewFilter Interface
First I enabled the SimpleFilteredTreeModel to set filter roules dynamically by introducing an interface (ViewFilter) and three implementions according to the alternatives shown in the isShown method. The filter is set by a method setViewFilter(ViewFilter).
2. Step: Update the Model
The method setViewFilter(ViewFilter) basically sets the new filter and tries to update the model so it shows up under the new behaviour.
    public void setViewFilter(ViewFilter filter) {
        this.filter = filter;
        // Notify the model
        final TreeNode root = (TreeNode) getRoot();
        final int childCount = root.getChildCount();
        final int[] indices = new int[childCount];
        final Object[] children = new Object[childCount];
        for (int i = 0; i < childCount; i++) {
            indices[i] = i;
            children[i] = getChild(root, i);
        fireTreeStructureChanged(this, new Object[]{root}, indices, children);
    }However, the view does not move at all. I tried also reload() and nodeChange(root) of the filter model and its delegate. No success.
If somebody knows how to extend this example to work dynamically, I would appreciate it highly.
-- Thanks
-- Daniel Frey
// File: SimpleFilteredTreeModel.java
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreeNode;
public class SimpleFilteredTreeModel extends DefaultTreeModel {
    private DefaultTreeModel delegate;
    public SimpleFilteredTreeModel(DefaultTreeModel delegate) {
        super((TreeNode) delegate.getRoot());
        this.delegate = delegate;
    public Object getChild(Object parent, int index) {
        int count = 0;
        for (int i = 0; i < delegate.getChildCount(parent); i++) {
            final Object child = delegate.getChild(parent, i);
            if (isShown(child)) {
                if (count++ == index) {
                    return child;
            else {
                final Object child2 = getChild(child, index - count);
                if (child2 != null) {
                    return child2;
                count += getChildCount(child);
        return null;
    public int getIndexOfChild(Object parent, Object child) {
        return delegate.getIndexOfChild(parent, child);
    public int getChildCount(Object parent) {
        int count = 0;
        for (int i = 0; i < delegate.getChildCount(parent); i++) {
            final Object child = delegate.getChild(parent, i);
            if (isShown(child)) {
                count++;
            else {
                count += getChildCount(child);
        return count;
    public boolean isLeaf(Object node) {
        return delegate.isLeaf(node);
    private boolean isShown(Object node) {
        final DefaultMutableTreeNode treeNode = (DefaultMutableTreeNode) node;
        final Object obj = treeNode.getUserObject();
        //return obj instanceof TestFilteredTreeModel.Datum1 || obj instanceof TestFilteredTreeModel.Datum2;
        //return obj instanceof TestFilteredTreeModel.Datum1;
        return obj instanceof TestFilteredTreeModel.Datum2;
// File: TestFilteredTreeModel
import java.util.Arrays;
import java.util.List;
import java.util.Random;
import java.util.ArrayList;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.MutableTreeNode;
import javax.swing.tree.TreeNode;
import javax.swing.tree.TreeModel;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.JTree;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
public class TestFilteredTreeModel {
    private DefaultMutableTreeNode[] nodes = new DefaultMutableTreeNode[0];
    public static void main(String[] args) {
        new TestFilteredTreeModel();
    public TestFilteredTreeModel() {
        final TreeNode root = createRootNode();
        final TreeModel model = new SimpleFilteredTreeModel(new DefaultTreeModel(root));
        final JTree tree = new JTree(model);
        final JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(new JScrollPane(tree));
        f.setSize(200, 300);
        f.setVisible(true);
    // Random tree generation
    private Random random = new Random();
    private TreeNode createRootNode() {
        final MutableTreeNode rootNode = createRandomNode();
        updateCache(rootNode);
        for (int i = 0; i < 30; i++) {
            final DefaultMutableTreeNode childNode = createRandomNode();
            pickRandom(nodes).add(childNode);
            updateCache(childNode);
        return rootNode;
    private void updateCache(MutableTreeNode childNode) {
        final List list = new ArrayList(Arrays.asList(nodes));
        list.add(childNode);
        nodes = (DefaultMutableTreeNode[]) list.toArray(new DefaultMutableTreeNode[0]);
    private DefaultMutableTreeNode createRandomNode() {
        final Datum[] data = new Datum[]{new Datum2(), new Datum1()};
        return new DefaultMutableTreeNode(data[random.nextInt(2)]);
    private DefaultMutableTreeNode pickRandom(DefaultMutableTreeNode[] nodes) {
        return nodes[random.nextInt(nodes.length)];
    public static class Datum {
        private static int counter = 0;
        protected int thisCounter = 0;
        public Datum() {
            thisCounter = counter++;
    public static class Datum2 extends Datum {
        public String toString() {
            return "Datum2 " + thisCounter;
    public static class Datum1 extends Datum {
        public String toString() {
            return "Datum1 " + thisCounter;
// file: ViewFilter.java
import javax.swing.tree.DefaultMutableTreeNode;
public interface ViewFilter {
    boolean isShown(DefaultMutableTreeNode node);
// file: Data1Filter.java
import javax.swing.tree.DefaultMutableTreeNode;
public class Data1Filter implements ViewFilter {
    public boolean isShown(DefaultMutableTreeNode node) {
        final Object obj = node.getUserObject();
        return obj instanceof TestFilteredTreeModel.Datum1;
// file: Data2Filter.java
import javax.swing.tree.DefaultMutableTreeNode;
public class Data2Filter implements ViewFilter {
    public boolean isShown(DefaultMutableTreeNode node) {
        final Object obj = node.getUserObject();
        return obj instanceof TestFilteredTreeModel.Datum2;
// file: Data12Filter.java
import javax.swing.tree.DefaultMutableTreeNode;
public class Data12Filter implements ViewFilter {
    public boolean isShown(DefaultMutableTreeNode node) {
        final Object obj = node.getUserObject();
        return obj instanceof TestFilteredTreeModel.Datum1 || obj instanceof TestFilteredTreeModel.Datum2;
}

Answer 1

The filtering works (after a fasion). Please clarify your problem.
I extended SimpleFitleredTreeModel as you described, along with changing isLeaf to use the filter
if (filter != null)  return filter.isShown( treeNode );I extended TestFiltredTreeModel constructor as follows, add the member
import javax.swing.*;
import java.awt.event.*;
private SimpleFilteredTreeModel model;Altered TestFilteredTreeModel constructor as follows:
       JMenuBar bar = new JMenuBar();
        JMenu menu = new JMenu("Filters");
        JMenuItem item;
        item = new JMenuItem( "Data1Filter" );
        item.addActionListener( new ActionListener() {
               public void actionPerformed( ActionEvent ev ) {
                    model.setViewFilter( new Data1Filter() );
          menu.add( item );
        item = new JMenuItem( "Data2Filter" );
        item.addActionListener( new ActionListener() {
               public void actionPerformed( ActionEvent ev ) {
                    model.setViewFilter( new Data2Filter() );
          menu.add( item );
        item = new JMenuItem( "Data12Filter" );
        item.addActionListener( new ActionListener() {
               public void actionPerformed( ActionEvent ev ) {
                    model.setViewFilter( new Data12Filter() );
          menu.add( item );
        bar.add( menu );
        f.setJMenuBar( bar );