clockdemo.java

用JAVA线程编写的时钟小应用程序已经过调 试运行无错误

import java.awt.Graphics;
import java.awt.Color;
import java.util.Date;
public class  ClockDemo extends java.applet.Applet implements Runnable
{
	Date timeNow;
	Clock myClock;
	Thread clockThread=null;
	public void start() {
	     if (clockThread==null)
	     {
			 clockThread=new Thread(this);
			 clockThread.start();
	     }
	}
	public void stop() {
	    clockThread.stop();
		clockThread=null;
	}
	public void run() {
	    while (true)
	    {
			repaint();
			try
			{
				Thread.sleep(1000);
			}
			catch (InterruptedException e){}
			
			
	    }
	}
	/*public void update(Graphics g)
	{
		myClock.clear(g,100,100,100,getBackground());
		g.setColor(getForeground());
		paint(g);
	}*/
	public void paint(Graphics g){
	    timeNow=new Date();
		myClock=new Clock(timeNow.getHours(),timeNow.getMinutes(),timeNow.getSeconds());
		g.drawString(timeNow.toString(),25,240);
		myClock.show(g,100,100,100);
	};
	
}
class Clock
{
	Clock(int hrs,int min,int sec) 
		{
		   hour=hrs%12;
		   minute=min;
		   second=sec;
	}
	void show(Graphics g,int center_x,int center_y,int radius) {
	     int hrs_nid_len=(int)(radius*0.5),
			 min_nid_len=(int)(radius*0.7),
			 sec_nid_len=(int)(radius*0.85);
		 double theta;
		 g.drawOval(center_x-radius,center_y-radius,radius*2,radius*2);
		 theta=(double)(hour*60*60+minute*60+second)/43200.0*2.0*Math.PI;
		 drawNiddle(g,Color.blue,center_x,center_y,hrs_nid_len,theta);
		 theta=(double)(minute*60+second)/3600.0*2.0*Math.PI;
		 drawNiddle(g,Color.blue,center_x,center_y,min_nid_len,theta); 
		 theta=(double) second/60.0*2.0*Math.PI;	
		 drawNiddle(g,Color.red,center_x,center_y,sec_nid_len,theta); 
 }
 /*void clear(Graphics g,int center_x,int center_y,int radius,Color clearColor)
	{
       int hrs_nid_len=(int)(radius*0.5),
			 min_nid_len=(int)(radius*0.7),
			 sec_nid_len=(int)(radius*0.85);
		 double theta;
		// g.drawOval(center_x-radius,center_y-radius,radius*2,radius*2);
		 theta=(double)(hour*60*60+minute*60+second)/43200.0*2.0*Math.PI;
		 drawNiddle(g,clearColor,center_x,center_y,hrs_nid_len,theta);
		 theta=(double)(minute*60+second)/3600.0*2.0*Math.PI;
		 drawNiddle(g,clearColor,center_x,center_y,min_nid_len,theta); 
		 theta=(double) second/60.0*2.0*Math.PI;	
		 drawNiddle(g,clearColor,center_x,center_y,sec_nid_len,theta); 
 }*/
 private void drawNiddle(Graphics g,Color c,int x,int y,int len,double theta) {
      g.setColor(c);
	  g.drawLine(x,y,(int)(x+len*Math.sin(theta)),(int)(y-len*Math.cos(theta)));
 }
 int hour,minute,second;
}