我想实现左边有两个选项卡,每个选项卡在右边又对应有5个选项卡,但是代码实现不了,我是照着书敲的,麻烦大家帮我看看问题出哪里了?


//选项卡
//

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

public class J41 extends JFrame implements ChangeListener
{

   private JTabbedPane jtp1=new JTabbedPane();
   private JTabbedPane jtp2=new JTabbedPane();
   private JTabbedPane jtp3=new JTabbedPane();
   JLabel jl=new JLabel("您选中了换行法师的选项卡0",JLabel.CENTER);




    public J41()
    {
        jtp1.addTab("换行方式",jtp2);
        jtp1.addTab("滚动方式",jtp3);
        jtp2.setTabLayoutPolicy(JTabbedPane.WRAP_TAB_LAYOUT);
        jtp3.setTabLayoutPolicy(JTabbedPane.SCROLL_TAB_LAYOUT);
        for(int i=0;i<6;i++)
        {
            jtp2.addTab("Tab"+i,new JLabel("这里是选项卡"+i,JLabel.CENTER));
            jtp3.addTab("Tab"+i,new JLabel("这里是选项卡"+i,JLabel.CENTER));


        }
        this.add(jtp1);
        this.add(jl,BorderLayout.CENTER);
        jtp1.addChangeListener(this);
        jtp2.addChangeListener(this);
        jtp3.addChangeListener(this);


        this.setBounds(100,100,500,200);
        this.setVisible(true);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }



    public void stateChanged(ChangeEvent e)
    {
        //获取外层选项卡窗格当前选中的选项卡索引
        int indexOuter=jtp1.getSelectedIndex();
        //获取内层选项卡窗格当前选中的选项卡索引
        int indexInner
            =((JTabbedPane)jtp1.getSelectedComponent()).getSelectedIndex();
        jl.setText("您选中了"+jtp1.getTitleAt(indexOuter)+"选项卡"+indexInner);
    }
 

     
   
    public static void main (String args[])
    {
        J41 j41=new J41();


    }

}