Problem with JTree in expanded mode?

Question

Hi I have a JTree and I have added few nodes to it. Now when i run my program it is displaying all the nodes in the expanded mode. but at some point of time i need to add few more nodes. when i am am adding nodes to the root node when the tree in expanded mode the newly added nodes are not visible. They are not getting added. what could be the problem? how do i add nodes to the tree when in expanded mode as well as remove few nodes when in expanded mode?
My code is as follows.
import java.awt.BorderLayout;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
public class Main extends JFrame{
     private DefaultMutableTreeNode top;
     public JTree mainTree;
     public Main(){
          super();
          JDesktopPane dp=new JDesktopPane();          
          dp.setLayout(new BorderLayout());
          top =new DefaultMutableTreeNode("All Active Nodes");                    
          mainTree=new JTree(top);          
          JScrollPane mtsp=new JScrollPane(mainTree);
          dp.add(mtsp,BorderLayout.CENTER);
          this.setContentPane(dp);          
          this.setDefaultCloseOperation(DISPOSE_ON_CLOSE);          
          this.setSize(300, 550);
          this.setVisible(true);
     public static void main(String[]args)throws Exception{
          Main as=new Main();
          DefaultMutableTreeNode top=as.getTop();
          DefaultMutableTreeNode node=new DefaultMutableTreeNode("murali");
          top.add(node);
          as.mainTree.expandRow(0);          
          Thread.sleep(10000);
          System.out.println("there");
          DefaultMutableTreeNode node1=new DefaultMutableTreeNode("murali12");
          top.add(node1);
      * @return the top
     public DefaultMutableTreeNode getTop() {
          return top;
}

Answer 1

I got the solution. The solution is to invoke nodesWereInserted(TreeNode node, int[] childIndices) this on treeModel after adding nodes are removing nodes.