Thread RUNNABLE or WAITING

[Pushkar]

I am working on some thread problems . In one of the problems , I have to check the state of a thread. What I am doing is, I create a thread , assign one task to it and after starting it I pass this thread to a method ,which checks thread's state using thread.getState().Now the problem is, for one of the thread , in run() method, I created one object and called wait() method on it. Now for this thread some times thread.getState() returns WAITING and some times RUNNABLE. I am surprised that how a waiting thread can be in RUNNABLE state.

Here is the code snippet :

try {
final Object obj = "";
Thread t2 = new Thread(new Runnable() {


public void run() {


try {


synchronized (obj) {
obj.wait();
}


} catch (InterruptedException e) {

}

}
});

t2.start();



Here t2.getState() gives WAITING 9 out of 10 times but once it also gives RUNNABLE.

Please help me out from this problem

[r035198x]

It reaches the RUNNABLE state before it reaches the waiting state.

Sometimes the main thread is calling getState before the waiting state is reached.

[Pushkar]

Thanks for quick reply. I totally agree with u, but the thing is how can i ensure that the waiting state.

[r035198x]

How can you ensure what?
What is the problem that you are trying to solve here?
Why are you unhappy with the thread getting into the RUNNABLE state first?

[Pushkar]

Sorry for incomplete response.

I want to ensure the waiting state of thread t2, because according to my problem structure, I have to interrupt a waiting thread .

So how can I prevent thread t2 to enter from waiting to runnable state.

[r035198x]

If you want to keep the thread waiting then don't call notify/notifyAll as you are already doing. If you want to do something only when t2 is in waiting state then set a flag when t2 starts waiting and continously check for that flag. All this smells bad.
What really is the object of this exercise?

[Pushkar]

Actually I m a student and I have been given these exercises as assignments. That is why I have posted this problem

[r035198x]

Why not post the exact problem description for this one.

[Steve11235]

Just loop and check the state until it goes to waiting, with a short sleep() in the loop.

[Lil_Aziz1]

Yea like Steve11235 mentioned, just sleep() for couple of seconds and then do getState()

[Steve11235]

As long as I'm back here... A few *milli* seconds.