Runnablej接口

public class Example8_4{
 public static void main(String arg[]){
  Left targetOfLeft=new Left();
  Thread left=new Thread(targetOfLeft);
  Right targetOfRight=new Right();
  Thread right=new Thread(targetOfRight);
  left.start();
  right.start();
  while(true){
   if(targetOfLeft.n==8||targetOfRight.n==8)
   System.exil(0);
  }
 }
}
class  Left implements Runnable{
 int n=0;
 public void run(){
  while(true){
   n++;
   System.out.printf(" %s","我在左面写字");
   try{
    Thread.sleep((int)(Math.random()*100)+100);
   }
   catch(InterruptedException e){}
  }
 }
}
class Right implements Runnable{
 int n=0;
 public void run(){
  while(true){
   n++;
   System.out.printf(" %40s","我在右面写字");
   try{
    Thread.sleep((int)(Math.random()*100)+100);
   }
   catch(InterruptendException e){}
  }
 }
}