JTree的用法

最新推荐文章于 2022-05-12 16:25:51 发布

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本文介绍了一个使用 Java Swing 的 JTree 控件创建树形结构视图的示例程序。该程序展示了如何构建多层次的节点结构，并通过监听选择事件来显示所选节点的路径、索引及对象。

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.*;

class JTreeTest
{
JFrame f = new JFrame("JTree的用法");
JScrollPane jsp = new JScrollPane();
JPanel jp = new JPanel(new GridLayout(3,1,5,10));
JLabel l1 = new JLabel("显示节点路径");
JLabel l2 = new JLabel("显示节点索引");
JLabel l3 = new JLabel("显示节点对象");
Font ft = new Font("Serif",Font.BOLD,18);
JTree tr;
void go()
{
  DefaultMutableTreeNode root,node1,node11;
  f.getContentPane().add(jsp);
  f.getContentPane().add("East",jp);
  jp.add(l1);jp.add(l2);jp.add(l3);
  jp.setBackground(Color.white);
  root = new DefaultMutableTreeNode("学校");
  root.add(node1 = new DefaultMutableTreeNode("南京师范大学"));
  node1.add(node11 = new DefaultMutableTreeNode("数科院"));
  node11.add(new DefaultMutableTreeNode("计算机系"));
  node11.add(new DefaultMutableTreeNode("软件工程系"));
  node11.add(new DefaultMutableTreeNode("数学系"));
  node1.add(node11 = new DefaultMutableTreeNode("文学院"));
  node11.add(new DefaultMutableTreeNode("古代文学系"));
  node11.add(new DefaultMutableTreeNode("现代文学系"));
  root.add(node1 = new DefaultMutableTreeNode("东南大学"));
  node1.add(node11 = new DefaultMutableTreeNode("建筑学院"));
  node11.add(new DefaultMutableTreeNode("设计系"));
  node11.add(new DefaultMutableTreeNode("材料系"));
  node11.add(new DefaultMutableTreeNode("力学系"));
  node1.add(node11 = new DefaultMutableTreeNode("计算机学院"));
  node11.add(new DefaultMutableTreeNode("网络系"));
  node11.add(new DefaultMutableTreeNode("计算机安全系"));
  root.add(node1 = new DefaultMutableTreeNode("海南大学"));
  tr = new JTree(root);
  tr.setFont(ft);
  tr.setShowsRootHandles(true);
  jsp.getViewport().add(tr);
  l1.setFont(ft);
  l2.setFont(ft);
  l3.setFont(ft);
  f.setSize(400,350);
  f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  f.setResizable(true);
  f.setVisible(true);
  tr.addTreeSelectionListener(new TreeH());

}
public static void main(String[] args)
{
  JTreeTest that = new JTreeTest();
  that.go();
}
class TreeH implements TreeSelectionListener
{
  public void valueChanged(TreeSelectionEvent e)
  {
   TreePath tp;
   int idx;
   String str;
   DefaultMutableTreeNode dmt;
   tp = tr.getSelectionPath();
   dmt = (DefaultMutableTreeNode)tr.getLastSelectedPathComponent();
   str = (String)dmt.getUserObject();
   idx = tr.getRowForPath(tp);
   l1.setText(tp.toString());
   l2.setText("索引=" +idx);
   l3.setText(str);
  }
}
}