clock.java

JAVA程序设计课程中各章节的程序实例。

import java.awt.Graphics; 
import java.util.*; 
import java.text.DateFormat; 
import java.applet.Applet; 

public class Clock extends Applet implements Runnable { 
    private Thread clockThread = null; 
    public void start() { 
        if (clockThread == null) { 
            clockThread = new Thread(this, "Clock"); 
            clockThread.start(); 
        } 
    } 
    public void run() { 
        Thread myThread = Thread.currentThread(); 
        while (clockThread == myThread) { 
            repaint(); 
            try { 
                Thread.sleep(1000); 
            } catch (InterruptedException e) { 
                //the VM doesn't want us to sleep anymore, 
                //so get back to work 
            } 
        } 
    } 
    public void paint(Graphics g) { 
        //get the time and convert it to a date 
        Calendar cal = Calendar.getInstance(); 
        Date date = cal.getTime(); 
        //format it and display it 
        DateFormat dateFormatter = DateFormat.getTimeInstance(); 
        g.drawString(dateFormatter.format(date), 5, 10); 
    } 
    //overrides Applet's stop method, not Thread's 
    public void stop() { 
        clockThread = null; 
    } 
}