如何使用Applet显示时钟？（How to display clock using Applet?）

问题描述 (Problem Description)

如何使用Applet显示时钟？

解决方案 (Solution)

下面的示例演示如何使用String Class的valueOf（）方法显示时钟。 使用Calender类获得第二，分钟和小时。

import java.awt.*;
import java.applet.*;
import java.applet.*;
import java.awt.*;
import java.util.*;
public class ClockApplet extends Applet implements Runnable { 
   Thread t,t1;
   public void start() {
      t = new Thread(this);
      t.start();
   }
   public void run() { 
      t1 = Thread.currentThread();
      while(t1 == t) {
         repaint();
         try {
            t1.sleep(1000);    
         }
         catch(InterruptedException e){}
      }
   }
   public void paint(Graphics g) {
      Calendar cal = new GregorianCalendar();
      String hour = String.valueOf(cal.get(Calendar.HOUR));
      String minute = String.valueOf(cal.get(Calendar.MINUTE));
      String second = String.valueOf(cal.get(Calendar.SECOND));
      g.drawString(hour + ":" + minute + ":" + second, 20, 30);
   }
}

结果 (Result)

上面的代码示例将在启用Java的Web浏览器中生成以下结果。

View in Browser. 

以下是使用Applet显示时钟的另一个示例示例。

import java.applet.*;  
import java.awt.*;  
import java.util.*;  
import java.text.*;  
public class javaApplication6 extends Applet implements Runnable {  
   Thread t1 = null;  
   int hours = 0, minutes = 0, seconds = 0;
   String time = "";
   public void init() {  
      setBackground( Color.green);  
   }  
   public void start() {
      t1 = new Thread( this );
      t1.start();
   } 
   public void run() {
      try {
         while (true) {
            Calendar cal = Calendar.getInstance();  
            hours = cal.get( Calendar.HOUR_OF_DAY );  
            if ( hours > 12 ) hours -= 12;  
            minutes = cal.get( Calendar.MINUTE );  
            seconds = cal.get( Calendar.SECOND );
            SimpleDateFormat formatter = new SimpleDateFormat("hh:mm:ss");  
            Date d = cal.getTime();  
            time = formatter.format( d );
            repaint();  
            t1.sleep( 1000 ); 
         }  
      }  
      catch (Exception e) { }  
   } 
   public void paint( Graphics g ) {
      g.setColor( Color.blue );  
      g.drawString( time, 50, 50 );  
   }  
}