Wait and Notify

• The wait() method can be called to have the currently running thread wait for a notification.

• The wait() method can only be called by the current thread; if it is called by a different thread, a runtime error is generated:

  java.lang.IllegalMonitorStateException: current thread not owner

  (Note that this effects how the code is organized.)

• The wait() method must be called from within synchronized code (method or blocked), and must be inside a try/catch block for an InterruptedException or in a method that throws that exception.
• Once the thread enters the wait state, it remains there until it is notified, or for a time version of wait(), when the time is up.
• Another thread can call notify() or notifyAll() to notify a waiting thread that it can continue.
• Calling notify() will notify one thread that is waiting on that object, but you don't know which one.
• Calling notifyAll() will notify all threads waiting on that object.
• Also note, that wait() releases all locks, but sleep() does not.