生产者消费者中多线程安全问题（即线程间通信的安全问题）

 1 class Product
 2 {
 3     private String name;
 4     private int count;
 5     private boolean flag;
 6     
 7     //生产产品的功能
 8     public synchronized void produce(String name)
 9     {
10         while (flag) 
11         //if (flag)
12         {
13             try{wait();}catch (InterruptedException e){e.printStackTrace();}
14         }
15         this.name = name+"..."+count;
16         System.out.println(Thread.currentThread().getName()+"***生产了***"+this.name);
17         count++;
18         flag = true;
19         notifyAll();
20         //notify();
21     }
22 
23     //消费产品的功能
24     public synchronized void consume()
25     {
26         while (!flag)
27         //if (flag)
28         {
29             try{wait();}catch (InterruptedException e){e.printStackTrace();}
30         }
31         System.out.println(Thread.currentThread().getName()+"---消费了---"+this.name);
32         flag = false;
33         notifyAll();
34         //notify();
35     }
36 }
37 
38 //生产任务
39 class Producer implements Runnable
40 {
41     private Product pro;
42     public Producer(Product pro)
43     {
44         this.pro = pro;
45     }
46     public void run()
47     {
48         while(true)
49         {
50             pro.produce("笔记本电脑");
51         }
52     }
53 }
54 
55 //消费任务
56 class Consumer implements Runnable
57 {
58     private Product pro;
59     public Consumer(Product pro)
60     {
61         this.pro = pro;
62     }
63     public void run()
64     {
65         while(true)
66         {
67             pro.consume();
68         }
69     }
70 }
71 
72 class Demo
73 {
74     public static void main(String[] args) 
75     {
76         Product pro = new Product();
77         
78         Producer producer = new Producer(pro);
79         Consumer consumer = new Consumer(pro);
80 
81         new Thread(producer,"生产线01").start();
82         new Thread(consumer,"消费者01").start();
83         new Thread(producer,"生产线02").start();
84         new Thread(consumer,"消费者02").start();
85     }
86 }