Threading - wait()

The wait() method on an object can be called only in the synchronized context i.e. the current thread must have 开发者_开发技巧a lock on the object to invoke the wait() method. Now if a thread T1 has a lock on an object(obj) and invokes its wait method obj.wait() . How can other threads get lock on this object(obj) so that they can also call wait, which is already possessed T1 ?

wait releases the synchronized context. From the documentation:

The current thread must own this object's monitor. The thread releases ownership of this monitor and waits until another thread notifies threads waiting on this object's monitor to wake up (...)

You only need to be synchronized for the duration of calling the wait() method, not for the duration of the wait time.