Table of Contents
- 1 How do you call wait () method using IF block or loop Why?
- 2 What happens if you don’t call wait and notify from synchronized block?
- 3 What happens when a thread executes wait method on an object without owning the objects lock?
- 4 Is it possible to call the wait method in a non Synchronised block?
- 5 Is it important to acquire object lock before calling wait () notify () and notify all ()?
- 6 How do I notify a waiting thread?
- 7 Can Notify be called after wait?
- 8 Why do we need to call wait() inside a synchronized method/block?
- 9 Why should wait() always be called inside a loop?
How do you call wait () method using IF block or loop Why?
To guarantee liveness, programs must test the while loop condition before invoking the wait() method. This early test checks whether another thread has already satisfied the condition predicate and sent a notification. Invoking the wait() method after the notification has been sent results in indefinite blocking.
What happens if you don’t call wait and notify from synchronized block?
If you don’t use synchronized together with wait() or notify() , another thread could enter the same block instead of waiting for the monitor to enter it.
What happens when a thread executes wait method on an object without owning the objects lock?
A thread cannot call wait(), notify() or notifyAll() without holding the lock on the object the method is called on. If it does, an IllegalMonitorStateException is thrown. Once a thread is awakened it cannot exit the wait() call until the thread calling notify() has left its synchronized block.
What is difference between wait () and sleep () method?
It tells the calling thread (a.k.a Current Thread) to wait until another thread invoke’s the notify() or notifyAll() method for this object, The thread waits until it reobtains the ownership of the monitor and Resume’s Execution….Difference between wait and sleep in Java.
| Wait() | Sleep() |
|---|---|
| Wait() is not a static method. | Sleep() is a static method. |
Is it possible to call the wait () method in a non synchronized block?
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.
Is it possible to call the wait method in a non Synchronised block?
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. Now when the methods are called no exception is thrown.
Is it important to acquire object lock before calling wait () notify () and notify all ()?
If no threads are waiting in the waiting queue, then notify() and notifyAll() have no effect. Before calling the notify() or notifyAll() method of an object, a thread must own the lock of the object. Hence it must be in one of the object’s synchronizedmethods or synchronized block.
How do I notify a waiting thread?
There are two ways of notifying waiting threads.
- 4.1. notify() For all threads waiting on this object’s monitor (by using any one of the wait() methods), the method notify() notifies any one of them to wake up arbitrarily.
- 4.2. notifyAll() This method simply wakes all threads that are waiting on this object’s monitor.
How do you use wait and notify?
When wait() is called on a thread holding the monitor lock, it surrenders the monitor lock and enters the waiting state. When the notify() is called on a thread holding the monitor lock, it symbolizes that the thread is soon going to surrender the lock. There can be multiple threads in the waiting state at a time.
Can Wait method be overloaded?
The wait() method is overloaded to accept a duration. The notify() method is overloaded to accept a duration. Both wait() and notify() must be called from a synchronized context.
Can Notify be called after wait?
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.
Why do we need to call wait() inside a synchronized method/block?
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 should wait() always be called inside a loop?
Why should wait() always be called inside a loop. The primary reason why while loops are so important is race conditions between threads. Certainly spurious wakeups are real and for certain architectures they are common, but race conditions are a much more likely reason for the while loop.
What happens if I don’t use wait() and notify() together?
If you don’t use synchronized together with wait () or notify (), another thread could enter the same block instead of waiting for the monitor to enter it.
What happens if a thread calling wait() method does not own the inherent lock?
If a thread calling wait () method does not own the inherent lock, an error will be thrown. We’ll now create Sender and Receiver and implement the Runnable interface on both so that their instances can be executed by a thread. First, we’ll see how Sender will work: