Java JTree collapse entire tree

import java.awt.Container;
import java.awt.FlowLayout;
import java.util.Enumeration;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.TreePath;

public class Main {
   public static void main(String args[]) {
      final JFrame f = new JFrame("JTree Demo");
      f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      Container c = f.getContentPane();
      c.setLayout(new FlowLayout());
      DefaultMutableTreeNode root = new DefaultMutableTreeNode("Root");
      DefaultMutableTreeNode c1 = new DefaultMutableTreeNode("A");
      DefaultMutableTreeNode c2 = new DefaultMutableTreeNode("B");
      DefaultMutableTreeNode c3 = new DefaultMutableTreeNode("C");
      root.add(c1);//from   www  .  j  a  va 2 s.co  m
      root.add(c2);
      root.add(c3);

      c1.add(new DefaultMutableTreeNode("1"));
      c1.add(new DefaultMutableTreeNode("2"));

      c2.add(new DefaultMutableTreeNode("3"));
      c2.add(new DefaultMutableTreeNode("4"));

      c3.add(new DefaultMutableTreeNode("5"));
      DefaultMutableTreeNode n6 = new DefaultMutableTreeNode("6");

      c3.add(n6);

      JTree t = new JTree(root);

      collapseEntireTree(t, root, true);

      c.add(new JScrollPane(t));
      f.pack();
      f.setVisible(true);
   }

   public static void collapseEntireTree(JTree tree, DefaultMutableTreeNode root, boolean collapseRoot) {

      Enumeration<DefaultMutableTreeNode> children = root.children();

      while (children.hasMoreElements()) {
         DefaultMutableTreeNode child = children.nextElement();

         if (child.children().hasMoreElements()) {
            collapseEntireTree(tree, child, collapseRoot);
         }
         tree.collapsePath(new TreePath(child.getPath()));
      }

      if (collapseRoot) {
         tree.collapsePath(new TreePath(root.getPath()));
      }
   }
}