java中线程存活和线程执行的问题！

 1 /*
 2 下面的程序会出现下面的情况，当Thread-0， Thread-1， Thread-2都被wait的时候，可能会同时苏醒
 3     Thread-0 put
 4     Thread-1 put
 5     Thread-2 put
 6     Thread-3 get//在此处，Thread-3拿到锁之后，将所有的等待的线程唤醒，才有了下面的输出
 7     Thread-2 put
 8     Thread-1 put
 9     Thread-0 put
10 */
11 
12 
13    虽然多个线程会同时苏醒，但是只有一个能获得cpu的执行权！
14    总之，同步中执行的只能是一个，但是存活的不一定就是一个！
15 
16 
17 class DuckD{
18     public void put(){
19         
20         synchronized(DuckD.class){
21           
22               System.out.println(Thread.currentThread().getName()+" put");
23               try{
24                  DuckD.class.wait();//Thread-0， Thread-1， Thread-2可能会同时在这里苏醒！
25               }catch(InterruptedException e){
26                  
27               }
28               //........
29         }
30     }
31     
32     public void get(){
33         
34         synchronized(DuckD.class){
35 
36                 DuckD.class.notifyAll();
37               System.out.println(Thread.currentThread().getName()+" get");
38               try{
39                  DuckD.class.wait();
40               }catch(InterruptedException e){
41                  
42               }         
43         }
44     }
45 }
46 
47 class ProduceD implements Runnable{
48     DuckD dk;
49     ProduceD(DuckD dk){
50        this.dk=dk;
51     }
52     public void run(){
53        while(true)
54          dk.put();
55     }    
56 }
57 
58 class ConsumeD implements Runnable{
59     DuckD dk;
60     ConsumeD(DuckD dk){
61        this.dk=dk;
62     }
63     public void run(){
64         while(true)
65           dk.get();
66     }    
67 }
68 
69 class Test{
70    public static void main(String[] args){
71        DuckD dk=new DuckD();
72        Thread t1=new Thread(new ProduceD(dk));
73        Thread t2=new Thread(new ProduceD(dk));
74        Thread t3=new Thread(new ProduceD(dk));
75        Thread t4=new Thread(new ConsumeD(dk));
76        
77        t1.start();
78        t2.start();
79        t3.start();
80        t4.start();
81    }
82 }

 

转载于:https://www.cnblogs.com/hujunzheng/p/3920873.html