Enthuware

Hi,
The sleep method doesn't release the lock ? So can we consider the thread not be running ?

Yes, even if the lock is not released, the thread is not running.

- The thread is trying to enter a synchronized block and the monitor is not free.
In this situation, the thread will be blocked until some other thread calls notify()/notifyAll() on the object whose synchronized block this thread is trying to enter.

In this case why thread trying to get monitor, will be blocked until other thread call notify()/notifyAll()? It may be the case that thread tries to get monitor for just synchronized method or block and there is no called wait method.
Isn't it possible ?

And also when some thread tries to get monitor isn't it in running state still?

When the thread tries to get a monitor and if the monitor is not free, then it gets blocked. It was running but not anymore. That is how threading has been designed in Java. Only when another thread that is holding the lock notifies blocked threads, will the blocked threads will be unblocked and become ready to run again.

Also please note that JLS considers a running and runnable thread as 'runnable' state only.

In which of the following cases a thread will definitely be alive but not be running?

The thread has issued a call to wait( ). (Assuming that the thread owns the lock for the object on which wait is called.)
In this situation, the thread will be blocked until some other thread calls notify()/notifyAll() on the object on which this thread has called wait() and this thread is able to reacquire the lock for this object.

Since the thread has already issued the call. Therefore, another thread may have called notify(), so the thread is not definitely not running.

Zoom in a little Right after the call to main, before anything else happens, the thread is definitely not running.

"before anything else happens"
This is not stated in the question