Is List.iterator() thread-safe?

Question

In Java: Is List.iterator() thread-safe, i.e. does the returned iterator reflect the current state of the list at any time or just the state of the list at the

Answer 1

No iterator is thread-safe. If the underlying collection is changed amidst iteration, a ConcurrentModificationException is thrown.

Even iterators of synchronized collections are not thread-safe - you have to synchronize manually.

One exception is the CopyOnWriteArrayList, which holds a snapshot during iteration.