写一个不会动的时钟

package thinking;import java.awt.*;import javax.swing.*;import java.util.*;public class My extends JFrame{public My(){StillClock clock = new StillClock();MessagePanel messagePanel = new MessagePanel("" + clock.getHour() + ":" + clock.getMinute() + ":" + clock.getSecond());messagePanel.setCenter(true);messagePanel.setForeground(Color.blue);messagePanel.setFont(new Font("Courier",Font.BOLD,16));setLayout(new GridLayout(0,1,5,5));add(messagePanel);add(clock);}public static void main(String[] args){My frame = new My();frame.setTitle("DisplayClock");frame.setSize(500,500);frame.setLocationRelativeTo(null);frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);frame.setVisible(true);}}class MessagePanel extends JPanel{private String message = "welcome to Java!";private boolean centered;private int xCoodinate = 20;private int yCoodinate = 20;public MessagePanel(){}public MessagePanel(String message){this.message = message;}public String getMessage(){return message;}public void setMessage(String message){this.message = message;repaint();}public boolean isCenter(){return centered;}public void setCenter(boolean centered){this.centered = centered;}protected void paintComponent(Graphics g){super.paintComponent(g);if(centered){FontMetrics fm = g.getFontMetrics();int stringWidth = fm.stringWidth(message);int stringAscent = fm.getAscent();xCoodinate = getWidth()/2 - stringWidth/2;yCoodinate = getHeight()/2 - stringAscent/2;}g.drawString(message, xCoodinate, yCoodinate);}}class StillClock extends JPanel{private int hour;private int minute;private int second;public StillClock(){setCurrentTime();}public StillClock(int hour , int minute , int second){this.hour = hour;this.minute = minute;this.second = second;}public int getHour(){return hour;}public void setHour(int hour){this.hour = hour;repaint();}public int getMinute(){return minute;}public void setMinute(int minute){this.minute = minute;repaint();}public int getSecond(){return second;}public void setSecond(int second){this.second = second;repaint();}protected void paintComponent(Graphics g){super.paintComponent(g);int clockRadius = (int)(Math.min(getWidth(), getHeight())*0.8*0.5);int xCenter = getWidth()/2;int yCenter = getHeight()/2;g.setColor(Color.BLACK);g.drawOval(xCenter - clockRadius , yCenter - clockRadius , 2*clockRadius , 2*clockRadius); g.drawString("12", xCenter - 5 , yCenter - clockRadius + 12);g.drawString("9", xCenter - clockRadius + 3 , yCenter + 5);g.drawString("3", xCenter + clockRadius - 10 , yCenter + 3);g.drawString("6", xCenter - 3 , yCenter + clockRadius - 3);int sLength = (int)(clockRadius * 0.8);int xSecond = (int)(xCenter + sLength * Math.sin(second * (2 * Math.PI/60)));int ySecond = (int)(yCenter - sLength * Math.cos(second * (2 * Math.PI/60)));g.setColor(Color.RED);g.drawLine(xCenter,yCenter,xSecond,ySecond);int mLength = (int)(clockRadius * 0.65);int xMinute = (int)(xCenter + mLength * Math.sin(minute * (2 * Math.PI/60)));int yMinute = (int)(yCenter - mLength * Math.cos(minute * (2 * Math.PI/60)));g.setColor(Color.BLUE);g.drawLine(xCenter, yCenter, xMinute, yMinute);int hLength = (int)(clockRadius * 0.5);int xHour = (int)(xCenter + hLength * Math.sin(hour * (2 * Math.PI/60)));int yHour = (int)(yCenter - hLength * Math.cos(hour * (2 * Math.PI/60)));g.setColor(Color.BLACK);g.drawLine(xCenter, yCenter, xHour, yHour);}public void setCurrentTime(){Calendar calendar = new GregorianCalendar();this.hour = calendar.get(Calendar.HOUR_OF_DAY);this.minute = calendar.get(Calendar.MINUTE);this.second = calendar.get(Calendar.SECOND);}public Dimension getPreferredSize(){return new Dimension(200,200);}}