关于JTabbedPane,该如何处理

import java.awt.Dimension;import java.awt.event.MouseAdapter;import java.awt.event.MouseEvent;import javax.swing.BorderFactory;import javax.swing.JFrame;import javax.swing.JPanel;import javax.swing.JTabbedPane;public class TabPane {    private JPanel pane1,pane2,pane3;    private JTabbedPane tabbedPane;    private int count;        TabPane(){        JFrame jf=new JFrame();        jf.setSize(520,500);        Dimension screen  = jf.getToolkit().getScreenSize();//获取屏幕大小        jf.setLocation(screen.width/2-jf.getSize().width/2,screen.height/2-jf.getSize().height/2);//设置程序居中显示                tabbedPane = new JTabbedPane(JTabbedPane.TOP);//切换面边标题在上面        pane1=new JPanel();        pane2=new JPanel();        pane3=new JPanel();        count=3;                        tabbedPane.addTab("1",null,pane1,"第1个Tab");//加入面板,实现多面板切换        tabbedPane.addTab("2",null,pane2,"第2个Tab");        tabbedPane.addTab("3",null,pane3,"第3个Tab");        tabbedPane.addTab("+",null,null,"添加新面板");                tabbedPane.addMouseListener(new MouseAdapter() {//选项卡点击事件            public void mouseClicked(MouseEvent arg0) {                addtab();//调用addtab方法            }        });                tabbedPane.setBorder(BorderFactory.createEmptyBorder(35,0,0,0));//设置tabPane与周边的距离        jf.add(tabbedPane);                jf.setVisible(true);    }        public void addtab(){        if(tabbedPane.getSelectedComponent()==null){            JPanel newpane=new JPanel();//新的面板            count++;            tabbedPane.removeTabAt(tabbedPane.getTabCount()-1);            tabbedPane.addTab(count+"",null,newpane,"第"+count+"个Tab");            tabbedPane.addTab("+",null,null,"添加新面板");        }    }        public static void main(String[] args){        new TabPane();    }}