多线程_先产后销_运行结果有BUG

class Shop
{
    public static void main(String[] args)
    {
        Things t=new Things();
        Custom c=new Custom(t);
        Producer p=new Producer(t);
        p.start();
        c.start();

    }
}

class Producer extends Thread
{
    private Things t;
    public Producer(Things t)//和customer传入的是同一个Things对象，因此共享区域（同步函数）可以实现同步
    {
        this.t=t;//局部变量的作用域妙用，不必命名地复杂难记
        // TODO Auto-generated constructor stub
    }

    public void run()
    {
        for (int i = 1; i < 10; i++)
        {
            t.putNum(i);

        }
    }
}

class Custom extends Thread
{
    Things t;
    public Custom(Things t)//和customer传入的是同一个Things对象，因此共享区域（同步函数）可以实现同步
    {
        this.t=t;
        // TODO Auto-generated constructor stub
    }

    public void run()
    {
        while(true)
        {
            System.out.println("get "+t.getNum());
        }

    }

}

class Things
{
    private int num=0;
    boolean bFull=false;

    public synchronized void putNum(int i)
    {

        if(!bFull)
        {
            this.num=i;
            this.bFull=true;
            System.out.println(num);
            notify();
        }

        try
        {
            wait();
        } catch (InterruptedException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    public synchronized int getNum()
    {
        if(!bFull)
        {

            try {
                wait();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

        this.bFull=false;
        notify();
        return num;

    }
}

不定时的出现如下非预期的运行结果：

put =1
put =2
get 1
get 2
put =3
get 3
put =4
get 4
put =5
get 5
put =6
get 6
put =7
get 7
put =8
get 8
put =9
get 9