On 29/05/2015 2:08 AM, Ulf Zibis wrote:
Hi all,
in the Javadoc of notify(), notifyAll() and wait(...) I read, that this
methods should only be used with synchronisation on it's instance.
So I'm wondering, why they don't have the synchronized modifier out of
the box in Object class.
Because, as others have said, the way you use a monitor is to acquire
the monitor lock, then inspect/modify mutable object state, then do a
wait/notify/notifyAll as appropriate, and finally release the monitor.
Making the methods themselves synchronized would be useless from a
synchronization correctness perspective and would prevent coding errors
from resulting in IllegalMonitorStateException.
Also I think, the following note should be moved from wait(long,int) to
wait(long):
/The current thread must own this object's monitor. The thread releases
ownership of this monitor and waits until either of the following two
conditions has occurred://
/
* /Another thread notifies threads waiting on this object's monitor to
wake up either through a
call to the notify method or the notifyAll method./
* /The timeout period, specified by timeout milliseconds plus nanos
nanoseconds arguments, has
elapsed. /
Why would you move it when wait(long) already has the more detailed:
* <p>
* The current thread must own this object's monitor.
* <p>
* This method causes the current thread (call it <var>T</var>) to
* place itself in the wait set for this object and then to relinquish
* any and all synchronization claims on this object. Thread <var>T</var>
* becomes disabled for thread scheduling purposes and lies dormant
* until one of four things happens:
...
David
-----
Cheers,
Ulf
