About Question enthuware.ocpjp.v8.2.1707 :

[johnlong]

Hi

Answer says : All modification operations of a CopyOnWriteArrayList are considered atomic.
Just to clarify - all modifications ( i.e. add() ) or modifications that write multiple elements (i.e. addAll() ) will be atomic?

[admin]

Yes, that is correct.

[johnlong]

Sorry, which statement is correct?

a) all modifications ( i.e. add() )
or
b) modifications that write multiple elements (i.e. addAll() )

I believe it is option b only.

[admin]

Well, all modifications include all modifications even though it doesn't make much sense for a single modification. A single modification is, nevertheless, atomic.

[johnlong]

But batch of single modifications run from one method would not block, correct?

[admin]

Not sure what you mean. Please post code.