Java Swing - 如何创建JTree节点可变工具提示

import java.awt.Component;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;

import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.ToolTipManager;
import javax.swing.tree.DefaultTreeCellRenderer;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreeNode;

public class Main {
  public static void fillTree(Node parent, int level, String label) {
    for (int i = 0; i < 5; i++) {
      Node node = new Node(label + " " + i);
      parent.addNode(node);
      if (level > 0) {
        fillTree(node, level - 1, label);
      }
    }
  }
  public static void main(String[] args) {
    Node root = new Node("Root");
    fillTree(root, 5, "tree label");
    DefaultTreeModel model = new DefaultTreeModel(root);

    JTree tree = new JTree(model);
    ToolTipManager.sharedInstance().registerComponent(tree);
    tree.setCellRenderer(new MyTreeCellRenderer());
    JFrame f = new JFrame();
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.add(new JScrollPane(tree));
    f.pack();
    f.setVisible(true);
  }
}

class MyTreeCellRenderer extends DefaultTreeCellRenderer {
  int rendering = 0;
  @Override
  public Component getTreeCellRendererComponent(JTree tree, Object value,
      boolean sel, boolean expanded, boolean leaf, int row, boolean hasFocus) {
    Component cell = super.getTreeCellRendererComponent(tree, value, sel,
        expanded, leaf, row, hasFocus);
    if (cell instanceof JComponent) {
      ((JComponent) cell).setToolTipText("Hello " + rendering++);
      if (value instanceof Node && cell instanceof JLabel) {
        ((JLabel) cell).setText(((Node) value).name);
      }
    }
    return cell;
  }
}

class Node implements TreeNode {

  private Node parent;
  private List<Node> children;
  public String name;

  public Node(String name) {
    this.name = name;
    this.children = new ArrayList<Node>();
  }

  public void addNode(Node child) {
    children.add(child);
    child.parent = this;
  }

  @Override
  public TreeNode getChildAt(int childIndex) {
    return children.get(childIndex);
  }

  @Override
  public int getChildCount() {
    return children.size();
  }

  @Override
  public Node getParent() {
    return parent;
  }

  @Override
  public int getIndex(TreeNode node) {
    return children.indexOf(node);
  }

  @Override
  public boolean getAllowsChildren() {
    return true;
  }

  @Override
  public boolean isLeaf() {
    return children.size() == 0;
  }

  @Override
  public Enumeration<Node> children() {
    return Collections.enumeration(children);
  }
}