Re: building DefaultTreeM

  To: comp.lang.java.gui

Jeff Higgins wrote:


Solution follows:


Takes about five minutes to fill my JTree this way
with about 58000 groups :P
I guess a lazy load will be necessary.

package newsgroup;

import java.util.ArrayList;
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;

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

  private static void fillGroup(
      DefaultMutableTreeNode node,
      List<Group> lst, int count)
  {
    if(count < lst.size())
    {
      Enumeration children = node.children();
      String grpString = lst.get(count).getLabel();
      boolean contains = false;
      while(children.hasMoreElements())
      {
        DefaultMutableTreeNode tmpNode =
          (DefaultMutableTreeNode)children.nextElement();
        if(grpString.compareTo(
            tmpNode.getUserObject().toString()) == 0)
        {
          contains = true;
          node = tmpNode;
          count++;
        }
      }
      if(!contains)
      {
        while(count < lst.size())
        {
          DefaultMutableTreeNode newNode =
            new DefaultMutableTreeNode(lst.get(count));
          node.add(newNode);
          node = newNode;
          count++;
        }
      }
      else
      {
        fillGroup(node, lst, count);
      }
    }
  }

  private static void fillModel(
      DefaultMutableTreeNode current)
  {
    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);
    }

    for (List<Group> lst : groups)
    {
      fillGroup(current, lst, 0);
    }
  }

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

    public String getLabel()
    { return label; }

    public String toString()
    { return label; }
  }

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

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