Adding nodes to JTree (algorithm needed)...

Question

Hi,
I hope someone can give me a solution or at least a hint on how to solve the following problem:
I've a JTree with a DefaultMutableTreeNode as the root node. Now I'll have to add nodes dynamically in a specified order. The numbers in brackets are node ids. Here's an example:
[73691178][73691179]
[73691178][73691179][73359970]
[73691178][73691179][73359970][1762]
[73691178][73691179][73359970][3092]
[73691178][73691179][73359970][1396]
[73691178][73691179][73359970][2301]
[73691178][73691180]
[73691178][73691180][73359972]
[73691178][73691180][73359972][1762]
[73691178][73691180][73359972][3092]
[73691178][61262304]
...The first part specifies the root node (73691178) of my JTree, the next part specifies the node directly below the root node etc. - now I'll have to collect these values and build up my tree accordingly.
        private void buildUpTreeNodes(DefaultMutableTreeNode root) {
          if (root != null) {
               List childTreeNodes = new NamedQueriesDAOHibernate().fetchChildTreeNodes(_rootNodeId, _mcId);
               for (Iterator treeNodesIter = childTreeNodes.iterator(); treeNodesIter.hasNext();) {
                    NodeBean bean = (NodeBean) treeNodesIter.next();
                    DefaultMutableTreeNode newNode = new DefaultMutableTreeNode(bean);
                    List nodeIds = SwingUtil.extractNodeIdsFromNpath(bean.getNPathChild());
                    for (Iterator nodeIdsIter = nodeIds.iterator(); nodeIdsIter.hasNext();) {
                         Long nodeId = (Long) nodeIdsIter.next();
                         if (!_rootNodeId.equals(nodeId)) {
                              // not sure, what to do...
                    root.add(newNode);
childTreeNodes is a list with beans which contain the path information ([73691178][73691180], see above) among other things. The posting above adds every node to the root node which is not correct (the root node has to be changed according to the path information). Perhaps recursion is the only way to solve the problem but I'm not quite sure...
Can anyone show some kind of algorithm on how to build up my tree in correct order?
Thanks a lot and best regards
- Stephan

Answer 1

assuming you want to read in the ids from a text file (in the format shown),
perhaps something like this might do
import java.awt.*;
import java.io.*;
import javax.swing.*;
import javax.swing.tree.*;
class Testing
  java.util.Map<String,DefaultMutableTreeNode> nodes = new java.util.HashMap<String,DefaultMutableTreeNode>();
  JTree tree;
  public void buildGUI()
    String rootNode = "73691178";
    nodes.put(rootNode,new DefaultMutableTreeNode(rootNode));
    tree = new JTree(nodes.get(rootNode));
    loadTree();
    tree.expandRow(0);
    JFrame f = new JFrame();
    f.getContentPane().add(new JScrollPane(tree));
    f.setSize(200,200);
    f.setLocationRelativeTo(null);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setVisible(true);
  public void loadTree()
    try
      BufferedReader br = new BufferedReader(new FileReader("NodeIDs.txt"));
      String line = "";
      while ((line = br.readLine()) != null)
        String[] ids = line.replaceAll("\\[","").split("\\]");
        String newID = ids[ids.length-1];
        String parentID = ids[ids.length-2];
        nodes.put(newID,new DefaultMutableTreeNode(newID));
        nodes.get(parentID).add(nodes.get(newID));
      br.close();
    catch(IOException ioe){ioe.printStackTrace();}
  public static void main(String[] args)
    SwingUtilities.invokeLater(new Runnable(){
      public void run(){
        new Testing().buildGUI();
}