如何创建动态树？

private TreeNode root;private TreeNode selectedNode;public TreeBean() {root = new DefaultTreeNode("Root", null);List rootNodes<Employee> = SearchDao.getRootNodes();Iterator it = rootNodes.iterator();while (it.hasNext()) {TreeNode node1 = new DefaultTreeNode(**it.next()**, root);    ****}}public TreeNode getRoot() {return root;}public TreeNode getSelectedNode() {return selectedNode;}public void setSelectedNode(TreeNode selectedNode) {this.selectedNode = selectedNode;}public void addChildNode(ActionEvent actionEvent) {System.out.println("Selected Node: "+getSelectedNode().toString());TreeNode newNode = new DefaultTreeNode("Node New", getSelectedNode());getSelectedNode().setExpanded(true);}public void addTopicBelow(ActionEvent actionEvent){TreeNode newNode = new DefaultTreeNode("Node New", getSelectedNode().getParent());}public void deleteNode(ActionEvent actionEvent){ System.out.println("Node to be deleted: "+getSelectedNode().toString()); //getSelectedNode().}