You're calling both wait and notifyAll without using a synchronized block. In both cases the calling thread must own the lock on the monitor you call the method on.
From the docs for notify (wait and notifyAll have similar documentation but refer to notify for the fullest description):
This method should only be called by a thread that is the owner of this object's monitor. A thread becomes the owner of the object's monitor in one of three ways:
- By executing a synchronized instance method of that object.
- By executing the body of a synchronized statement that synchronizes on the object.
- For objects of type Class, by executing a synchronized static method of that class.
Only one thread at a time can own an object's monitor.
Only one thread will be able to actually exit wait at a time after notifyAll as they'll all have to acquire the same monitor again - but all will have been notified, so as soon as the first one then exits the synchronized block, the next will acquire the lock etc.