class Buffer2                              //加互斥鎖的緩沖區
{
    private int value;
    private boolean isEmpty = true;        //value是否為空的信號量
    synchronized void put(int i)
    {
        while (!isEmpty)                   //當value不空時,等待
        {
            try
            {
                 this.wait();              //等待
            }
            catch(InterruptedException e)
            {
                 System.out.println(e.getMessage());
            }
        }
        value = i;                         //當value空時,value獲得值
        isEmpty = false;                   //設置value為不空狀態
        notify();                          //喚醒其他等待線程
    }
    synchronized int get()
    {
        while (isEmpty)                    //當value空時,等待
        { 
            try
            {
                 this.wait();
            }
            catch(InterruptedException e)
            {
                 System.out.println(e.getMessage());
            }
        }
        isEmpty = true;                    //設置value為空狀態,并返回值
        notify();
        return value;                      
    }
}
class Sender2 extends Thread               //發送線程
{
    private Buffer2 bf;
    public Sender2(Buffer2 bf)
    {
        this.bf = bf;
    }
    public void run( )
    {
        for (int i=1;i<6;i++)
        {
            bf.put( i );
            System.out.println("Sender  put : " + i );
        }
    }
    public static void main (String args[])
    {
        Buffer2 bf = new Buffer2();
        (new Sender2(bf)).start();
        (new Receiver2(bf)).start();
    }
}
class Receiver2 extends Thread             //接受線程
{
    private Buffer2 bf;
    public Receiver2(Buffer2 bf)
    {
        this.bf = bf ;
    }
    public void run()
    {
        for (int i=1; i<6;i++)
            System.out.println("\t\t     Receiver get : " + bf.get()) ;
    }
}