设计2个线程，其中一个线程每次对j增加1，另外一个线程对j每次减少1

请大侠提供源代码！谢谢了！

三个类：

加1：
[code="java"]import java.util.concurrent.atomic.AtomicInteger;

public class AddNum extends Thread {
private AtomicInteger i;

public AddNum(AtomicInteger i) {
    this.i = i;
}

@Override
public void run() {
    synchronized (i) {
        i.getAndIncrement();
        System.out.println(i);
    }
}

}[/code]

减1：

[code="java"]import java.util.concurrent.atomic.AtomicInteger;

public class SubstractNum extends Thread {
private AtomicInteger i;

public SubstractNum(AtomicInteger i) {
    this.i = i;
}

@Override
public void run() {
    synchronized (i) {
        i.decrementAndGet();
        System.out.println(i);
    }
}

}[/code]

测试类：
[code="java"]import java.util.concurrent.atomic.AtomicInteger;

public class TestThread {

public static void main(String[] args) {
    AtomicInteger i = new AtomicInteger(30);

    for (int j = 0; j < 1000; j++) {
        new AddNum(i).start();
        new SubstractNum(i).start();
    }
}

}[/code]

[code="java"]import java.util.concurrent.*;
/**

• 通过内部类实现线程的共享变量
  

• */
  
  public class ThreadTest { //测试类
  public static void main(String[] args) {
  ExecutorService exec = Executors.newCachedThreadPool();//线程池
  Mythread thread = new Mythread();
  exec.execute(thread.getThread());//执行线程Thread
  exec.execute(thread.getThreadAnother());//执行线程ThreadAnother
  exec.shutdown();//不许再提交新的线程。
  }
  
  }
  
  class Mythread {
  
  int index = 0; // 共享变量

  private class InnerThread extends Thread { //内部类
  
  public synchronized void run() {
  
  while(true)
  
  try {
  System.out.println(Thread.currentThread().getName()
  
  + "is running and index is " + index++); //++1
  TimeUnit.MICROSECONDS.sleep(1000*100);//休眠
  } catch (InterruptedException e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
  }

  }   
  

  }
  
  private class InnerThreadAnother extends Thread { //内部类
  public synchronized void run() {
  
  while (true) {
  
  try {
  TimeUnit.MICROSECONDS.sleep(1000*100);//休眠
  System.out.println(Thread.currentThread().getName()
  
  + "is running and index is " + index--); //减减1
  } catch (InterruptedException e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
  }
  }
  
  }
  
  }
  public Thread getThreadAnother() {
  
  return new InnerThreadAnother();
  
  }
  
  public Thread getThread() {
  
  return new InnerThread();
  
  }
  
  } [/code]

参考这里讲的多线程间通信的两个方法：共享变量及管道流
[url=http://blog.csdn.net/sodino/archive/2009/07/27/4383916.aspx]http://blog.csdn.net/sodino/archive/2009/07/27/4383916.aspx[/url]

自己动手啊，

提供个学习资料集
http://www.ibm.com/developerworks/cn/java/j-concurrent/