Simply put,
calling wait() forces the current thread
to wait until some other thread invokes notify() or notifyAll() on the same object. For this, the current thread must own the object’s monitor.
Why do we need the wait () and notify () methods?
We wait on an object if we are waiting for some condition to change
– some resource to become available. We notify on an object if we want to awaken sleeping threads. There can be any number of lock objects in your program – each locking a particular resource or code segment.
What is wait () notify ()?
The wait() method causes
the current thread to wait until another thread invokes
the notify() or notifyAll() methods for that object. The notify() method wakes up a single thread that is waiting on that object’s monitor. The notifyAll() method wakes up all threads that are waiting on that object’s monitor.
Can Notify be called after wait?
5 Answers.
Nothing stops you calling notify
on an object that’s not being wait ed by another thread. I’d strongly recommend not re-inventing the wheel. Java’s Future interface is designed for results that may only arrive later, and the FutureTask class implements this interface.
Can we use wait and 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.
What is wait () and notify () in multithreading?
The wait() method causes
the current thread to wait until another thread invokes
the notify() or notifyAll() methods for that object. The notify() method wakes up a single thread that is waiting on that object’s monitor. The notifyAll() method wakes up all threads that are waiting on that object’s monitor.
Does notify Release lock?
No — notify / notifyAll
don’t release locks like wait does
. The awakened thread can’t run until the code which called notify releases its lock. … The thread then waits until it can re-obtain ownership of the monitor and resumes execution.
What happens if notify () is called and no thread is in waiting state?
In other words, if the notify() method is called when no other thread is waiting,
notify() simply returns and the notification is lost
. A thread that later executes the wait() method has to wait for another notification to occur.
What happens when notify () is called and no thread is waiting?
In other words, if the notify() method is called when no other thread is waiting,
notify() simply returns and the notification is lost
. A thread that later executes the wait() method has to wait for another notification to occur.
What will happen if wait () is called from message 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.
Which method is overloaded to accept a duration?
The
wait() method
is overloaded to accept a duration.
What is the difference between wait () notify () and notifyAll ()?
The
wait()
method causes the current thread to wait until another thread invokes the notify() or notifyAll() methods for that object. The notify() method wakes up a single thread that is waiting on that object’s monitor. The notifyAll() method wakes up all threads that are waiting on that object’s monitor.
Can we override wait () or notify () methods?
Can we override wait() or notify() methods? Ans.
wait and notify are declared final in object class and hence cannot be overridden
.
Why wait notify and notifyAll is declared in object class instead of thread?
If wait() and notify() were on the Thread instead then
each thread would have to know the status of every other thread and there is no way to know thread1
that thread2 was waiting for any resource to access. Hence, notify, wait, notifyAll methods are defined in object class in Java.
Which method is used to notify all the threads which are waiting for a lock?
We use the
notify() method
for waking up threads that are waiting for an access to this object’s monitor.
Does wait method release lock?
The major difference is that
wait() releases the lock or monitor
while sleep() doesn’t releases the lock or monitor while waiting. wait() is used for inter-thread communication while sleep() is used to introduce pause on execution, generally. Thread.
