building DefaultTreeModel

  To: comp.lang.java.gui
Hi,
  I hope someone can explain to me how to build
my DefaultTreeModel from a List of delimited Strings.

I get from my news server a list
(some tens of thousands) of newsgroups in the form:

comp.lang.java.gui
comp.lang.java.help
comp.lang.java.programmer
news.software.nntp
news.software.readers
rec.models.railroad
rec.models.scale

Now, my latest attempt to build GroupTreeModel
produces:

MyNewsServer
  |
   comp
     |
      lang
        |
         java
           |
            gui
  |
   comp
     |
      lang
        |
         java
           |
            help

Instead of the desired:

MyNewsServer
  |
   comp
     |
      lang
        |
         java
           |
            gui
           |
            help
           |
            programmer

Also, with tens of thousands of groups
I haven't been able to wait long enough
for this method to complete. I've waited
some tens of minutes, I don't think there's
an infinite loop, I think it is just taking
a very long time - not sure.

Anyway, the GroupTreeDemo.fillModel()
method is my latest attempt, I hope someone
will help me accomplish my goal.

Thanks,
Jeff Higgins

package newsgroup;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.Enumeration;
import java.util.List;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.MutableTreeNode;
import javax.swing.tree.TreeNode;

@SuppressWarnings("serial")
public class GroupTreeDemo extends JFrame
{
  public GroupTreeDemo()
  {
    super("GroupTreeModel Demo");
    setSize(300, 400);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    Group f = new Group("MyNewsServer");
    DefaultMutableTreeNode root =
      new DefaultMutableTreeNode(f);
    GroupTreeModel model =
      new GroupTreeModel(root, new StringComparator());
    fillModel(model);
    JTree tree = new JTree(model);
    getContentPane().add(new JScrollPane(tree));
  }

  private void fillModel(GroupTreeModel model)
  {
    String[] myGroups =
    { "comp.lang.java.gui",
      "comp.lang.java.help",
      "comp.lang.java.programmer",
      "news.software.nntp",
      "news.software.readers",
      "rec.models.railroad",
      "rec.models.scale"
    };
    ArrayList<List<Group>> groups =
      new ArrayList<List<Group>>(myGroups.length);
    List<Group> list;
    for (String str : myGroups)
    {
      list = new ArrayList<Group>();
      String[] strArray = str.split("\\.");
      for (String s : strArray)
      {
        list.add(new Group(s));
      }
      groups.add(list);
    }

    // here is where I attempt to build my model
    for (List<Group> lst : groups)
    {
      DefaultMutableTreeNode current =
        (DefaultMutableTreeNode) model.getRoot();
      for (Group g : lst)
      {
        boolean contains = false;
        Enumeration enumeration = current.children();
        while (enumeration.hasMoreElements())
        {
          if (enumeration.nextElement() == g)
          {
            contains = true;
          }
        }
        if (!contains)
        {
          DefaultMutableTreeNode tmp =
            new DefaultMutableTreeNode(g);
          current.add(tmp);
          current = tmp;
        }
      }
    }
  }

  public class Group
  {
    String label;
    public Group(String s)
    { label = s; }

    public String getLabel()
    { return label; }

    public String toString()
    { return label; }
  }

  public class StringComparator
  implements Comparator<TreeNode>
  {
    public int compare(TreeNode o1, TreeNode o2)
    {
      if (!(o1 instanceof DefaultMutableTreeNode
          && o2 instanceof DefaultMutableTreeNode))
      {
        throw new IllegalArgumentException(
  "Can only compare DefaultMutableTreeNode objects");
      }
      String s1 = ((DefaultMutableTreeNode) o1)
      .getUserObject().toString();
      String s2 = ((DefaultMutableTreeNode) o2)
      .getUserObject().toString();
      return s1.compareToIgnoreCase(s2);
    }
  }

  @SuppressWarnings("serial")
  class GroupTreeModel extends DefaultTreeModel
  {
    private Comparator<TreeNode> comparator;

    public GroupTreeModel(
        TreeNode node, Comparator<TreeNode> c)
    {
      super(node);
      comparator = c;
    }

    public GroupTreeModel(
        TreeNode node, boolean asksAllowsChildren,
        Comparator<TreeNode> c)
    {
      super(node, asksAllowsChildren);
      comparator = c;
    }

    public void insertNodeInto(
        MutableTreeNode child, MutableTreeNode parent)
    {
      int index = findIndexFor(child, parent);
      super.insertNodeInto(child, parent, index);
    }

    public void insertNodeInto(
        MutableTreeNode child, MutableTreeNode par, int i)
    {
      // The index is useless in this model,
      // so just ignore it.
      insertNodeInto(child, par);
    }

    // Perform a recursive binary search
    // on the children to find the right
    // insertion point for the next node.
    private int findIndexFor(
        MutableTreeNode child, MutableTreeNode parent)
    {
      int cc = parent.getChildCount();
      if (cc == 0)
      {
        return 0;
      }
      if (cc == 1)
      {
        return comparator.compare(
            child, parent.getChildAt(0)) <= 0 ? 0 : 1;
      }
      // First & last index
      return findIndexFor(child, parent, 0, cc - 1);
    }

    private int findIndexFor(
        MutableTreeNode child, MutableTreeNode parent,
        int i1, int i2)
    {
      if (i1 == i2)
      {
        return comparator.compare(
        child, parent.getChildAt(i1)) <= 0 ? i1 : i1 + 1;
      }
      int half = (i1 + i2) / 2;
      if (comparator.compare(
          child, parent.getChildAt(half)) <= 0)
      {
        return findIndexFor(child, parent, i1, half);
      }
      return findIndexFor(child, parent, half + 1, i2);
    }
  }

  public static void main(String args[])
  {
    GroupTreeDemo demo = new GroupTreeDemo();
    demo.setVisible(true);
  }
}

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