JTree update

Question

Hey,
in one of the tools I am currently writing I am displaying data in a JTree.
The user can edit the data that goes with the nodes,save the tree (not yet) and load a tree from a local file.
Right now I want the user to be able to "reset" the tree. That means, whenever the user goes to "File - New Tree" he/she should get a new empty JTree.
I put the JTree into a JScrollpane, which is part of a SplitPane, which is part of a JPanel, which is part of a JFrame.
I wrote a little method "resetTree()" to update the tree.
In this method I tried to just call the setup method again - which build the tree in the first place - but I was still able to see the old tree in my GUI.
I tried to repaint all of the Panes above but that did not work either.
//My constructor:
public MyProgram() extends JPanel
JFrame frame = new JFrame("Test");
setupTree();
setupSplitpane(); //This just takes the two ScrollPanes (one for each side) and
//sets up a SplitPane
this.setLayout(new BorderLayout());
this.add(splitPane,BorderLayout.CENTER);
frame.getContentPane().add(this,BorderLayout.CENTER);
frame.pack();
//This is the method which I call when creating the tree for the first time.
private static void setupTree(String from)
//TreeBuilder builds the tree. It can read a local xml file into
//the tree. "from" is the path of the file. "data" is a Hashtable.
//The method puts the data from the xml file into "data" and builds a tree.
TreeBuilder myTreeBuilder = new TreeBuilder(from,data);
//"tree" is a global JTree. "getTree()" returns the JTree myTreeBuilder build.
tree = myTreeBuilder.getTree();
//treeView is the JScrollPane
treeView = new JScrollPane(tree);
treeView.setPreferredSize(new Dimension( leftWidth, windowHeight ));
tree.addMouseListener(new PopupListener(popup));
//This is the method I call when trying to reset the tree.
public void resetTree(String from)
data = null;
setupTree(from); //from = null in this case.
splitPane.repaint(); //Repaint the Splitpane
frame.repaint(); //Repaint the Frame
this.repaint(); // Repaint the Panel.
Again, my problem is, that when I call resetTree() the tree I can see in my GUI does not change. I want the tree in the left side of my JSplitpane to be setup again from zero (containing no data and no nodes) and than to update the GUI.
I hope somebody got what I am trying to do and is able to show me a solution or just give me a little hint on howto solve this problem.
THX!
Martin

Answer 1

Thank you very much!
I got it working like this:
JTree tree = myX.getTree();
DefaultTreeModel mdel = (DefaultTreeModel)(tree.getModel());
Object t = mdel.getRoot();
if(t instanceof DefaultMutableTreeNode)
DefaultMutableTreeNode root = (DefaultMutableTreeNode)(t);
root.removeAllChildren();          
mdel.reload();
Still quick and dirty but it works...
THX
Martin