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

class A extends JFrame implements TreeSelectionListener{
   JTextArea text=new JTextArea(20,20);
   JTree tree=null;
   public A(){
      super("实验");
      
      Container con=getContentPane();   //定义JFrame窗体容器
       
      DefaultMutableTreeNode root=new DefaultMutableTreeNode("c:\\");
      DefaultMutableTreeNode t1=new DefaultMutableTreeNode("备份资料");
      DefaultMutableTreeNode t2=new DefaultMutableTreeNode("Java学习");
      DefaultMutableTreeNode t1_1=new DefaultMutableTreeNode("思维论坛精华帖子");
      DefaultMutableTreeNode t1_2=new DefaultMutableTreeNode("来往邮件");
      DefaultMutableTreeNode t2_1=new DefaultMutableTreeNode("视频教程");
      DefaultMutableTreeNode t2_2=new DefaultMutableTreeNode("Java3D");   //定义结点

      JTree tree=new JTree(root);   
      root.add(t1);
      root.add(t2);   //定义root的子结点
 
      t1.add(t1_1);
      t1.add(t1_2);   //定义t1_1 t1_2为t1的结点

      t2.add(t2_1);
      t2.add(t2_2);   //定义t2_1 t2_2为t2的子结点
      
      JScrollPane s=new JScrollPane(text);   //带滚动条的面板（树放置其中）
      JSplitPane sp=new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,true,tree,s);
      con.add(sp);
      tree.addTreeSelectionListener(this);
      setVisible(true);
      setSize(300,300);
      validate();      
      addWindowListener(new WindowAdapter(){
         public void windowClosing(WindowEvent e){
            System.exit(0);
         }
      });
   }
   
   public void valueChanged(TreeSelectionEvent e){
      if(e.getSource()==tree){    //用来判断发起事件的控件是不是tree
         DefaultMutableTreeNode node=(DefaultMutableTreeNode)tree.getLastSelectedPathComponent();   //返回最后选定的节点
         if(node!=null && node.isLeaf()){               

            String str=node.toString();
            if(str.equals("思维论坛精华帖子")){
               text.setText(str);
            }
            else if(str.equals("来往邮件")){
               text.setText(str);
            }
            else if(str.equals("视频教程")){
               text.setText(str);
            }
            else if(str.equals("Java3D")){
               text.setText(str);
            } 
         }
         else{
               text.setText(node.getUserObject().toString());
            } 
      }
   }
}


class B{
   public static void main(String[]args){
      A a=new A();
   }
}