Why wait and notify called from synchronized method?

Why wait and notify called from synchronized method?

The wait() is called, so that the thread can wait for some condition to occur when this wait() call happens, the thread is forced to give up its lock. To give up something, you need to own it first. Thread needs to own the lock first. Hence the need to call it inside a synchronized method/block.

Why wait () notify () and notifyAll () methods have to be called from synchronized method?

Calling notify() or notifyAll() methods issues a notification to a single or multiple threads that a condition has changed and once the notification thread leaves the synchronized block, all the threads which are waiting for fight for object lock on which they are waiting and lucky thread returns from wait() method …

Can Wait notify without synchronized?

If you need to call wait(), notify(), or notifyAll() from within a non-synchronized method, then you must first obtain a lock on the object’s monitor. If you don’t, an exception will be generated when an attempt is made to call the method in question.

Can we use wait and notify without synchronized?

Is it possible to call the wait method in a non synchronized block?

What happens if thread waits outside synchronization block?

If Thread wait outside the synchronization block then there is no monitoring object and also other thread notify to access for the monitoring object, so how would the thread outside the synchronization block would know that it has been notified.

What happens if you do not synchronize before wait ( )?

The problem it may cause if you do not synchronize before wait () is as follows: If the 1st thread goes into makeChangeOnX () and checks the while condition, and it is true ( x.metCondition () returns false, means x.condition is false) so it will get inside it.

Why is wait always in a synchronized method in Java?

When a thread invokes d.wait, it must own the intrinsic lock for d — otherwise an error is thrown. Invoking wait inside a synchronized method is a simple way to acquire the intrinsic lock. When you call notify () from an object t, java notifies a particular t.wait () method. But, how does java search and notify a particular wait method.

Why is notify always called between isempty and wait?

Once you understand the issue, the solution is obvious: Use synchronized to make sure notify is never called between isEmpty and wait. Without going into details: This synchronization issue is universal.