Java wait（）/ notify（）在同一对象中不起作用？

Question

Essentially, this is what I'm trying to do:

1. A while loop is running some I/O code. It has a conditional section that executes if a volatile boolean is true. It then enters a synchronized block with a while loop. Standard practice. It calls 'this.wait()' and waits for the notification.

     while((len=ais.read(buff))>=0) { source.write(buff, 0, len); if(paused) { synchronized(this) { while(paused && playing) { try { System.out.println("waiting..."); this.wait(); System.out.println("out of wait"); } catch (InterruptedException e) { e.printStackTrace(); } } } } if(!playing) break; } 

2. Other methods in the SAME object change the boolean 'paused' to false. The method then calls 'this.notify'

    public void resume() { synchronized(this) { if(paused) { paused = false; this.notify(); } } } 

   The problem is when you call that method, the thread isn't waking up. The "out of wait" println never even prints. Why is this? Can you not do wait/notify within the same object.

Solved! Completely forgot that that first part of code (the waiting part) was in a nested class and therefore wasn't the same object. I came to realize this when I noticed their hash codes weren't the same.

Answer 1

Are paused and playing declared as volatile? It is possible that one of the threads does not see the other thread's modification of these global variables. Also, we do not know anything about the value of playing.

Answer 2

只需尝试使用notifyAll() ，一切都应该没问题