What is notify and notifyAll in Java?

Notification to number of threads : We can use notify() method to give the notification for only one thread which is waiting for a particular object whereas by the help of notifyAll() methods we can give the notification to all waiting threads of a particular object.

What is the difference between notify () and notifyAll () in Java?

1. First and main difference between notify() and notifyAll() method is that, if multiple threads are waiting on any locks in Java, notify method to send a notification to only one of the waiting thread while notifyAll informs all threads waiting on that lock.

When should I use notify () and notifyAll () methods in threads?

Useful differences:

• Use notify() if all your waiting threads are interchangeable (the order they wake up doesn’t matter), or if you only ever have one waiting thread.
• Use notifyAll() for other cases where the waiting threads may have different purposes and should be able to run concurrently.

What is notify () in Java?

notify() wakes up a single thread that is waiting on this object’s monitor. If many threads are waiting on this object, one of them is chosen to be awakened. The choice is arbitrary and occurs at the discretion of the implementation. A thread waits on an object’s monitor by calling one of the wait methods.

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 is the notifyAll method?

The notifyAll method wakes up all threads waiting on the object in question (in this case, the CubbyHole ). The awakened threads compete for the lock. The Object class also defines the notify method, which arbitrarily wakes up one of the threads waiting on this object.

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 join () in Java?

lang. Thread class provides the join() method which allows one thread to wait until another thread completes its execution. If t is a Thread object whose thread is currently executing, then t. join() will make sure that t is terminated before the next instruction is executed by the program.

Does wait method release lock?

Thread inside the synchronized method is set as the owner of the lock and is in RUNNABLE state. Any thread that attempts to enter the locked method becomes BLOCKED. When thread calls wait it releases the current object lock (it keeps all locks from other objects) and than goes to WAITING state.

What is notify function in Java?

– wait ( ) tells the calling thread to give up the monitor and go to sleep until some other thread enters the same monitor and calls notify ( ). – notify ( ) wakes up the first thread that called wait ( ) on the same object. – notifyAll ( ) wakes up all the threads that called wait ( ) on the same object. The highest priority thread will run first.

Why wait and notify is in object class in Java?

The threads can communicate with each other through wait (), notify () and notifyAll () methods in Java. These are final methods defined in the Object class and can be called only from within a synchronized context.

What is a method in Java?

Init method is a life cycle method for servlets for java. It is started by the browser when java program is loaded and run by the browser. Init method is a predefine method to initialize an object after its creation.

How to wait in Java?

The Wait method in Java hold the thread to release the lock till the thread hold the object. The most important point is to be remember that wait method is used inside the synchronized code. The wait ( ) is defined inside the object class. When the wait method is called the following event to be occurred –