Please let me know that where i can find the suitable and simple example to use wait(),notify() and notifyall() metods in java.....
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Thread communicates by using objects without referencing communicating threads. If these methods are moves to Thread class then each needs a reference to other thread to communicate with it. |
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I understand the essence of his question. I ask myself this question about once every 6 months... But her answer is complete. Usually notify all is not what you want. If your threads are waiting on the same lock, the notify all will waste time since only 1 thread can get through anyway. However, if your threads are simply waiting for ... |
notify will wake one thread, but you can not predict which one or that it will be the right one. notifyAll will wake all threads that are waiting on some lock. Best practice is usually to always invoke wait in a while loop with some condition test ("spin lock"), and use notifyAll. Having wait in a loop protects against accidental notifications ... |
Hi folks, Just wondering, from what I've read, there's no harm in replacing all calls to notify() in a program to notifyAll(). It seems that it might wake up threads that may not need waking, but they should be coded well enough to know to go back to sleep. This approach would make things faster/easier to code I feel. Regards, merlin_bar ... |
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Hi, wait() notify(), and notifyAll() are very rarely, if ever, called on a java.lang.Thread. Every Java object contains a lock (also called a "mutex"). When you call a synchronized method, the Thread that calls that method must "grab" the lock for the object the method is called on. This can only happen if no other Thread already holds the lock. While ... |
I am currently studying threads and synchronization. What I have not been able to figure out a detail in the difference between notify and notifyAll. I read that notifyAll() notifies all the threads that are waiting, and that notify() notifies only one thread waiting. I have no problem understanding who notifyAll() works. - What if I call notify() and there are ... |
Dear Friends...! What will happen if we use a wait() without having notify() call in the programme. According to the theory the thread waiting shoud wait forever until another thread notifies on that object, which the previous thread is waiting for . But in the following programme I coudn't see any differenecs in the out put when I use wait() with ... |
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Hi. The reason that these functions are in the Object class is because you want to be able to lock on any object and not only on Thread objects. For example, let's say i want to lock on a specific Class I created named Lock. Then i can use this code below even though Lock doesn't inherit from Thread (it is ... |
If zero or one threads are waiting on the object, notify() and notifyAll() do the same. If more than one thread is waiting, notify() only wakes up one of them, but notifyAll() wakes up all of them. You can't control which one is woken by notify(). In practice, notifyAll() is used much more often. |
I am having a lot of difficulty in using notify and notifyAll methods.Whenever i try to do so i get IllegalMonitorStateException:current class not owner. Please help me out.Please explain what this means and where am i doing wrong and what is the correct way to do it.All the books on this issue seem to confuse me.Here is my code.all the places ... |
From the point of view of completing a project, there's not a great deal to be gained by asking why things are how they are in the Java API and wishing they were different. Most things in Java are how they are for good reasons. Some things are not as good as they could be (clone, calendars etc.), but cannot change ... |
It is the object which has to wait for a monitor to finish. That is why Object has the wait() method in. In multithreading waiting is something which every object might ahve to do. That is why it is in the Object class. When the Object has finished doing whatever it has to do, it holds the responsibility for notifying other ... |
i have a doubt relating wait()/notify() Its said ,wait() without notify() is uselss. I tried , 1. It gave error ,illegalMonitorStateException .Is it because of missing notify() or some other error. 2. Will wait() keep on waiting indefinitly, without notify() unless some external /JVM interrupt comes. or wait() in such case doesnt work. Thnks |
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This has been covered before. In short, it's because most people like the ability to use objects that are not direct subclasses of Thread as lock objects for synchronization. If you take the time to think the issues through, you'll realise that an object like a Database connection pool store might not need to run in a thread, but still requires ... |
Hello group, I know that its a very lame question to ask experts like you but still i cannot help myself asking the question that "What is the Diffrence Between Notify & NotifyAll" method in the Object Class. Well so far my search on the Internet reveals that 'notify()' method wakes up a single thread waiting on the object and passes ... |
Why does the Object class have methods such as the wait, notify , notifyall? also Can we extend the Thread class and implement the runnable interface at the same time?.Why I am confused is because the effectiveness of the Runnable class is lost as we don't have methods such as sleep, join and yield as its members. though we can call ... |
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Folks, I know it's basic level questaion to ask. I have doubt is why these there methods wait(),notify(),notifyAll() is in object class? After so much digging i came up with some solution -> 1. JAVA is root heirarchy language and every ojbect has some internal thread run( like garbage collection thread).So if we put it in Thread then we have to ... |
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Dear all Please tell me why these wait(), notify() and notifyAll() methods have been defined in the Object class instead in Thread class ? As we know these three methods are used inside the synchronized block only then what is the use of defining these methods in Object class why they had not defined in Thread class.Evidently you see that these ... |
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Hi, The other day I was going through Kathy sierra/Bert bates book on SCJP and came across the code which is given as an example of wait/notify/notifyAll(chapter 9, code with classes - Reader and Calculator.). But the weird thing is that even if I remove the call to notify/notifyAll, the waiting threads come out of wait stage. Is this a case ... |
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Henry Wong wrote: As already mentioned, the reason these methods are part of the Object class, is because any object can be used for synchronization, and hence, any object should be able to be used for notification. Having these methods as part of the Object class is, of course, better than the Thread class, in this regard. However, there is a ... |
This question should probably be a sticky as we've answered it so many times .. if you search this forum you'll find several good answers and I recommend you do this. The quick answer is they apply to a specific object instance i.e. if you didn't implement them on object you'd be left with implementing some static functions on say a ... |
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Good question. So I looked at the API documentation for the wait() method of Object and it said: Causes current thread to wait until another thread invokes the notify() method or the notifyAll() method for this object. If your theory were correct, and there were three threads waiting for a single thread to notify them of completion, then two of the ... |
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A: Because wait() method is called in a lock context(where objects are involved, you should be able to call wait from any class not only from the thread class.) what wait() does : it suspends execution of the current thread until it recieves a notify) --> you cannot call wait from a thread class bcoz u hv no idea which thread ... |
I understand threading, I understand implementing and extending etc... But... I do not understand how to freaking implement wait() notify() and notifyAll()... Do not get me wrong, I understand exactly what they do... I've tried making a simple program that counts to 10 and then while the other thread is waiting, it's SUPPOSED to notify it to 'wake up' and for ... |
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Hi everyone, According to API docs, notify()/notifyAll() will only wake thread waiting for an Object's monitor as a result of calling one of the Object's method wait(). My question is: what if there are threads, which are waiting for an object's monitor, the wait() method has never been called and currently running thread which owns the monitor calls notify()/notifyAll() method ? ... |
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Hi I could not find when notifyAll fits in the concurrency maze. Say n threads are in the wait pool on an object, then notify and notifyall will have same effect, as ultimatly only one thread will actually accuire a lock and the rest will move to waiting state. Can any one tell me what i am missing here? Thanks Ashish ... |
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Second of all, the way that Thread is implemented, at least on windows, it that calling Thread.join does a wait() on that thread object. Thus, if you call notify() on a thread, you could actually be waking up joined threads, which wouldn't be good. And if you called wait, you could get woken up if the thread finishes which violates the ... |
Hi... I have doubt regading wait(), and notify(), and notifyall() methods this methods is useful only threads. why this methods give in the object class,insted of giveing Thread class. only sleep() method is given in Thread class. What is the reason...for all this methods, I would be very thankfull to given this answer Thank you Ramesh |