import java.util.*;import java.awt.*;import java.applet.*;public class Clock extends Applet implements Runnable {    Thread timer = null;    int lastxs=0, lastys=0, lastxm=0, lastym=0, lastxh=0, lastyh=0;    public void init()     {        setBackground(Color.white);                //設置Applet背景    }    public void paint(Graphics g)                  //顯示數字和圖形時鐘    {        int xh, yh, xm, ym, xs, ys, s, m, h, xcenter, ycenter;        Date rightnow = new Date();                //獲取當前日期和時間        String today = rightnow.toLocaleString();  //時間對應的字符串        s = rightnow.getSeconds();        m = rightnow.getMinutes();        h = rightnow.getHours();        xcenter=80;                                //圖形鐘的原點        ycenter=80;                      //以下計算秒針、分針、時針位置        xs = (int)(Math.cos(s * 3.14f/30 - 3.14f/2) * 45 + xcenter);        ys = (int)(Math.sin(s * 3.14f/30 - 3.14f/2) * 45 + ycenter);        xm = (int)(Math.cos(m * 3.14f/30 - 3.14f/2) * 40 + xcenter);        ym = (int)(Math.sin(m * 3.14f/30 - 3.14f/2) * 40 + ycenter);        xh = (int)(Math.cos((h*30+m/2)*3.14f/180-3.14f/2)*30+xcenter);        yh = (int)(Math.sin((h*30+m/2)*3.14f/180-3.14f/2)*30+ycenter);        g.setFont(new Font("TimesRoman", Font.PLAIN, 14));        g.setColor(Color.blue);        g.drawArc(xcenter-50,ycenter-50,100,100,0,360);    //畫圓和數字        g.setColor(Color.darkGray);        g.drawString("9",xcenter-45,ycenter+3);         g.drawString("3",xcenter+40,ycenter+3);        g.drawString("12",xcenter-5,ycenter-37);        g.drawString("6",xcenter-3,ycenter+45);        //時間變化時，需要重新畫各個指針，即先消除原有指針，然后畫新指針        g.setColor(getBackground());  //用背景色畫線，可以消除原來畫的線        if (xs != lastxs || ys != lastys)          //秒針變化        {            g.drawLine(xcenter, ycenter, lastxs, lastys);            g.drawString(today, 5, 150);           //消除數字時鐘        }        if (xm != lastxm || ym != lastym)          //分針變化        {            g.drawLine(xcenter, ycenter-1, lastxm, lastym);            g.drawLine(xcenter-1, ycenter, lastxm, lastym);         }        if (xh != lastxh || yh != lastyh)          //時針變化        {            g.drawLine(xcenter, ycenter-1, lastxh, lastyh);            g.drawLine(xcenter-1, ycenter, lastxh, lastyh);         }        g.setColor(Color.darkGray);                //顯示數字時鐘        g.drawString(today, 5, 150);          g.setColor(Color.blue);                    //畫新指針        g.drawLine(xcenter, ycenter, xs, ys);        g.drawLine(xcenter, ycenter-1, xm, ym);        g.drawLine(xcenter-1, ycenter, xm, ym);        g.drawLine(xcenter, ycenter-1, xh, yh);        g.drawLine(xcenter-1, ycenter, xh, yh);        lastxs=xs; lastys=ys;                      //保存指針位置        lastxm=xm; lastym=ym;        lastxh=xh; lastyh=yh;    }    public void start()                            //啟動線程    {        if(timer == null)        {             timer = new Thread(this);             timer.start();        }    }    public void stop()                             //停止線程     {        timer = null;    }     public void run()                    //每隔一秒鐘，刷新一次畫面    {        while (timer != null)         {             try              {             	Thread.sleep(1000);             }             catch (InterruptedException e) {}             repaint();                  //調用paint()方法重畫時鐘        }        timer = null;    }    public void update(Graphics g)     {        paint(g);                        //重寫該方法是為了消除抖動現象    }}