http://groups.google.com/groups?q=JTree+expand+all

TreeWillExpandListener

Christian

// If expand is true, expands all nodes in the tree.
// Otherwise, collapses all nodes in the tree.
public void expandAll(JTree tree, boolean expand) {
   TreeNode root = (TreeNode)tree.getModel().getRoot();
   
   // Traverse tree from root
   expandAll(tree, new TreePath(root), expand);
}
private void expandAll(JTree tree, TreePath parent, boolean expand) {
   // Traverse children
   TreeNode node = (TreeNode)parent.getLastPathComponent();
   if (node.getChildCount() >= 0) {
       for (Enumeration e=node.children(); e.hasMoreElements(); ) {
           TreeNode n = (TreeNode)e.nextElement();
           TreePath path = parent.pathByAddingChild(n);
           expandAll(tree, path, expand);
       }
   }
 
   // Expansion or collapse must be done bottom-up
   if (expand) {
       tree.expandPath(parent);
   } else {
       tree.collapsePath(parent);
   }
}