About Question enthuware.ocpjp.ii.v11.2.1101 :

[liugengyu]

Option B: remove(Object key) returns V, not boolean

[admin]

Right. That is why it is not the correct option.

[noeloo]

The explanation is clear, but only from options description one gets the impression that the methods are atomic in the Map interface.

[pavvel]

I see boolean remove(Object key, Object value) int specification here:
https://docs.oracle.com/en/java/javase/ ... ntMap.html

But in the answers, it is marked as an incorrect option.
Some kind of confusion.

[admin]

Yes, but the question asks for methods that are there in ConcurrentMap in addition to Map. The method you have mentioned exists in Map that is why it is not a correct option.