JTree Lazy Load Expand

I hope you are fine.

I have a JTree that I lazily load using a database query (each node). I have a button on the screen, and when the user clicks the button, I execute several insert/update/deletein the database, and then add the model back to Jtreeonly with the root and its immediate children using SQL (this collapses the tree and selects and all the smoothing of the extended nodes, which expected since this is a lazily loaded tree)

I want to execute, before the user presses the button on insert/update/delete, I read the entire extended state and saved it in memory, and then when I reinitialize the loop JtreeI through these extended children and will call jtree.expandPathbut it does not expand the nodes :(.

I even added the event TreeWillExpandListenerand in treeWillExpand, I added the code to get the data from the node database, and I see that the query is being executed to get the child screen, but Jtreeit still displays as collapsed.

I really need your help. Please advise. Here is a snippet of code.

package marketdatagui;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreeModel;
import javax.swing.tree.TreePath;
import javax.swing.event.TreeModelListener;
import javax.swing.event.TreeModelEvent;
import javax.swing.event.EventListenerList;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.util.HashMap;
import java.io.File;
import java.io.Serializable;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;


public class StressGroupModel
    implements TreeModel,Serializable, Cloneable
{
    protected EventListenerList listeners;

    private static final Object LEAF = new Serializable() { };

    private Map map;

    private NodeData root;

    private class NodeData{
        String id;
        String name;

        public String toString(){
            return name;
        }
    }

    public StressGroupModel()
    {
        this.root = new NodeData();
        root.id = "Root";
        root.name = "Root";

        this.listeners = new EventListenerList();

        this.map = new HashMap();

        List rootChildren = new ArrayList();

        NodeData d1 = new NodeData();
        d1.id = "5000007";
        d1.name = "Name5000007";

        rootChildren.add(d1);

        NodeData d2 = new NodeData();
        d2.id = "10000054";
        d2.name = "Name10000054";

        rootChildren.add(d2);
        map.put(root.id, rootChildren);
    }


    public Object getRoot()
    {
        return root;
    }

    public boolean isLeaf(Object node)
    {
        return map.get(node) == LEAF;
    }

    public int getChildCount(Object node)
    {
        List children = children(node);

        if (children == null)
            return 0;

        return children.size();
    }

    public Object getChild(Object parent, int index)
    {
        return children(parent).get(index);
    }

    public int getIndexOfChild(Object parent, Object child)
    {
        return children(parent).indexOf(child);
    }

    protected List children(Object node)
    {
        NodeData s = (NodeData)node;

        Object value = map.get(s.id);

        if (value == LEAF)
            return null;

        List children = (List)value;

        if (!"Root".equals(s.id))
        {
            String[][] dbData = getChildren(s.id);

            if (dbData != null)
            {
                children = new ArrayList(dbData.length);
                for (int i = 0; i < dbData.length; i++)
                {
                    NodeData d = new NodeData();
                    d.id = dbData[i][1];
                    d.name = dbData[i][1] + "Name";
                    children.add(d);
                    if ("R".equals(dbData[i][2]))
                        map.put(d, LEAF);
                }
            }
            else
                children = new ArrayList(0);

            map.put(s.id, children);       
        }

        return children;
    }

    private String[][] getChildren(String parent_uid){
        String sql = "select parent_uid,child_uid,child_type from stress_groups_mapping "
              + " where parent_uid="+ parent_uid
              +" order by parent_uid, child_uid";

        return Util.getTableData(sql);
    }

    public void valueForPathChanged(TreePath path, Object value)
    {
    }

    public void addTreeModelListener(TreeModelListener l)
    {
        listeners.add(TreeModelListener.class, l);
    }

    public void removeTreeModelListener(TreeModelListener l)
    {
        listeners.remove(TreeModelListener.class, l);
    }

    public Object clone()
    {
        try
        {
            StressGroupModel clone = (StressGroupModel)super.clone();

            clone.listeners = new EventListenerList();

            clone.map = new HashMap(map);

            return clone;
        }
        catch (CloneNotSupportedException e)
        {
            throw new InternalError();
        }
    }

}

• This is how I create a tree

public createTree {

JFrame f = new JFrame("Tree Dragging Tester");
          DefaultMutableTreeNode root = new DefaultMutableTreeNode(new Object());
          jtree = new JTree(new StressGroupModel());
          TreeWillExpandListener treeWillExpandListener = new TreeWillExpandListener() {
                public void treeWillCollapse(TreeExpansionEvent treeExpansionEvent)
                    throws ExpandVetoException {


                }

                public void treeWillExpand(TreeExpansionEvent treeExpansionEvent) throws ExpandVetoException {
                    TreePath path = treeExpansionEvent.getPath();
                    Object node =  path.getLastPathComponent();
                    ((StressGroupModel)jtree.getModel()).getChildCount(node);
                  }


          };

          jtree.addTreeWillExpandListener(treeWillExpandListener);

          f.getContentPane().add(jtree, BorderLayout.CENTER);
          f.setSize(300, 200);
          f.setVisible(true);
}

• This is how I save the advanced state

Enumeration paths = jtree.getExpandedDescendants (new TreePath (jtree.getModel () GetRoot ().));

• Insert / update / delete database files
• Now reinitialize the model and add it back to JTree (so that it selects the latest values ​​from the database)
• Now I execute a loop and call expand to expand the nodes that the user expanded before he clicked the button, but, alas, it crashed :(

jtree.setModel( StressGroupModel());           while (paths.hasMoreElements()) {

            TreePath treePath = (TreePath) paths.nextElement();

            try {

            jtree.expandPath(treePath);
            jtree.setSelectionPath(treePath);

            }
            catch(Exception ex){

            }

        }