e9_3.java

java 初学者学习实例

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class E9_3 extends Applet implements Runnable
{  Thread redBall,blueBall; Graphics redPen, bluePen;int t=0;
   public void init()
    {redBall=new Thread(this); blueBall=new Thread(this);
     redPen=getGraphics();
     bluePen=getGraphics();
     redPen.setColor(Color.red);
     bluePen.setColor(Color.blue);
    }
public void start()
{redBall.start ( ) ;blueBall.start ( );
}
public void run()
 { while (true)
  { t=t+1;
  if(Thread.currentThread()==redBall)
   {if(t>100) t=0;
        redPen.clearRect(0, 0, 110, 500);
        redPen.fillOval(50,  (int) (1.0/2*t*9.8), 5, 5);
        try{redBall.sleep(40);}
            catch(InterruptedException e){}
     }
      else if(Thread.currentThread()==blueBall)
         {bluePen.clearRect(120, 0, 900, 500);
          bluePen.fillOval(120+7*t,  (int) (1.0/2*t*9.8), 5, 5);
            try{blueBall.sleep(40);}
            catch(InterruptedException e){}
       }
    }
 }
}