怎么能让程序正常运行并且显示面板，请在基础上添加程序

import java.awt.event.*;import java.awt.*;class TestStopWatch extends Frame{    public TestStopWatch()    {        this.add(new StopWatch());            addWindowListener(new WindowAdapter()        {            public void WindowClosing(WindowEvent e)            {                dispose();                System.exit(0);            }        });    }    public static void main(String []args)    {        TestStopWatch sw=new TestStopWatch();    }}

import java.awt.*;import java.awt.Canvas;import java.text.SimpleDateFormat;import java.util.Date;import java.awt.event.*;public class StopWatch extends Canvas implements Runnable{    long startTime=0;    long endTime=0;    boolean start=false;    public StopWatch()    {        enableEvents(AWTEvent.MOUSE_EVENT_MASK);    }    protected void processMouseEvent(MouseEvent e)    {        if(e.getID()==MouseEvent.MOUSE_CLICKED)        {            startTime=endTime=System.currentTimeMillis();            repaint();            start=true;            new Thread(this).start();        }else if(e.getID()==MouseEvent.MOUSE_RELEASED)        {            endTime=System.currentTimeMillis();            repaint();            start=false;        }    }    public void paint(Graphics g)    {        SimpleDateFormat sdf=new SimpleDateFormat("HH:mm:ss");        Date date=null;        try        {            date=sdf.parse("00:00:00");        }catch(Exception e)        {            e.printStackTrace();        }        date.setTime(date.getTime()+endTime-startTime);        //new Date(endTime-startTime);        String strName=sdf.format(date);        g.fill3DRect(0,0,78,28,true);        g.setColor(Color.WHITE);        g.drawString(strName,10,20);    }    public void run()    {        while(start)        {            try            {                Thread.sleep(500);            }catch(Exception e)            {                e.printStackTrace();            }            endTime=System.currentTimeMillis();            repaint();        }    }}

import java.awt.event.*;import java.awt.*;class TestStopWatch extends Frame{    public TestStopWatch()    {        this.add(new StopWatch());            addWindowListener(new WindowAdapter()            {                public void windowClosing(WindowEvent e)    //这里写错了,你写成WindowClosing了                {                    dispose();                    System.exit(0);                }            });    }    public static void main(String []args)    {        TestStopWatch sw=new TestStopWatch();        //下面还要加两句        sw.setSize(400, 300);        sw.setVisible(true);    }}