繪製一個顯示當前時間的StiilClock

## ClockAnimation.java ##

`import javax.swing.*;
import java.awt.event.*;
public class ClockAniamtion extends JFrame{

private StillClock clock=new StillClock();
public ClockAniamtion()
{
    add(clock);
    Timer timer =new Timer(1000,new TimerListener());
    timer.start();
}

private class TimerListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
clock.setCurrentTime();
clock.repaint();
}
}
public static void main(String[] args)
{

JFrame frame=new ClockAniamtion();
frame.setTitle("ClockAAnimation");
frame.setSize(200,200);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);

}
}

    ##子類StillClock.java ##

import java.awt.*;

import javax.swing.*;
import java.util.*;

public class StillClock extends JPanel {
private int hour;
private int minute;
private int second;

/* Construct a default clock with the current time/
public StillClock() {
setCurrentTime();
}

/* Construct a clock with specified hour, minute, and second /
public StillClock(int hour, int minute, int second) {
this.hour = hour;
this.minute = minute;
this.second = second;
}

/* Return hour /
public int getHour() {
return hour;
}

/* Set a new hour /
public void setHour(int hour) {
this.hour = hour;
repaint();
}

/* Return minute /
public int getMinute() {
return minute;
}

/* Set a new minute /
public void setMinute(int minute) {
this.minute = minute;
repaint();
}

/* Return second /
public int getSecond() {
return second;
}

/* Set a new second /
public void setSecond(int second) {
this.second = second;
repaint();
}

/* Draw the clock /
protected void paintComponent(Graphics g) {
super.paintComponent(g);

// 初始化時鐘參數
int clockRadius =
  (int)(Math.min(getWidth(), getHeight()) * 0.8 * 0.5);
int xCenter = getWidth() / 2;
int yCenter = getHeight() / 2;

// 畫圓
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);

//畫秒針
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);

// 畫分針
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);

// 畫時針
int hLength = (int)(clockRadius * 0.5);
int xHour = (int)(xCenter + hLength *
  Math.sin((hour % 12 + minute / 60.0) * (2 * Math.PI / 12)));
int yHour = (int)(yCenter - hLength *
  Math.cos((hour % 12 + minute / 60.0) * (2 * Math.PI / 12)));
g.setColor(Color.BLACK);
g.drawLine(xCenter, yCenter, xHour, yHour);

}

public void setCurrentTime() {
// Construct a calendar for the current date and time
Calendar calendar = new GregorianCalendar();

// Set current hour, minute and second
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);
}
}
“`

注意我發表博客的時間。。。