Certification practice exam on timed wait

Question

Why is the second answer correct? What exception was thrown and why?

P.S. Thanks for the answer!

Now I see that t1.wait() shall be inside synchronized(t1) - on t1, the same instance used to call wait(). Also this answer was helpful.

This is a free test taken from here

you call `t1.wait()` without holding a lock on `t1` object so exception `IllegalMonitorStateException` will be thrown. — Michał Krzywański, Sep 10 '19 at 06:43
But go() instance method is synchronized, meaning I call wait() from a synchronized block - doesn't it prevent IllegalMonitorStateException ? — Code Complete, Sep 10 '19 at 06:47

score 4 · Accepted Answer · answered Sep 10 '19 at 06:48

Since this code calls t1.wait without holding the lock on t1 object - the IllegalMonitorStateException will be thrown - as is documented in Object::wait(time) method. This is a RuntimeException so it does not have to be specified in method signature. synchronized on Bees::go method will make sure that thread invoking this method will hold lock on Bees object - not t1 object.

Certification practice exam on timed wait

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