Analysis of a multi-threaded communication case

The procedure is as follows:

Public static void main (String[] args)  throws  Exception{     final list list = new arraylist ();     final object  lock = new object ();     thread t1 = new thread ( New runnable ()  {         @Override          public void run ()  {             synchronized  (Lock) {                 for (int i = 0 ; i < 10 ; i + +) {                     list.add (i);                     if (List.size ()  == 5) {                         lock.notify ();                          system.out.println (Thread.CurrentThread (). GetName ()  +  "give notice!");                      }                }             }             system.out.println (Thread.CurrentThread (). GetName ()  +  "execute  over! ");         }    });     thread  t2 = new&nbSp Thread (new runnable ()  {         @Override          public void run ()  {             synchronized  (Lock) {                 if (List.size ()  != 5) {                     try {                          lock.wait ();                     } catch  (interruptedexception e)  {                         &nbSp;e.printstacktrace ();                     }                 }                 system.out.println (Thread.CurrentThread (). GetName ()  +  "  receive notification!");             }             system.out.println (Thread.CurrentThread (). GetName ()  +  "execute  over! ");         }    });     t2.start () ;     thread.sleep (+);     t1.start ();}

Analysis:

The intention of the program is to use the communication between multithreading, using wait/notify implementation, but the result of the operation is that although the thread T1 issued a notification, but the thread T2 did not immediately receive notification to execute, this is why? because only the thread T1 execution has released the lock, T2 can execute, that is, wait/notify is not real-time (wait to release the lock, and notify does not release the lock caused ), then the real-time communication between the threads what to do? Can be achieved using Countdownlatch.

Improvements to the program:

Public static void main (String[] args)  throws  Exception{     final list list = new arraylist ();     final object  lock = new object ();     final countdownlatch countdownlatch  = new countdownlatch (1);     thread t1 = new thread (new  runnable ()  {         @Override          public void run ()  {                 for (int i = 0 ; i < 10 ;  i++) {                     list.add (i);                     if (List.size ()  == 5) {                          Countdownlatch.countdown ();                         system.out.println (Thread.currentThread (). GetName ()  +  "give notice!");                      }                }             system.out.println ( Thread.CurrentThread (). GetName ()  +  "execute over!");         }    });     thread  t2 = new thread (new runnable ()  {         @Override         public void  run ()  {                 if (List.size ()  != 5) {                     try {                          Countdownlatch.await ();                     } catch  (interruptedexception e)  {                          e.printstacktrace ();                     }                 System.out.println (Thread.CurrentThread (). GetName ()  +  "  receive notification!");             }             system.out.println (Thread.CurrentThread (). GetName ()  +  "execute  over! ");         }    });     t2.start () ;     thread.sleep (+);     t1.start ();}

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Analysis of a multi-threaded communication case