CopyOnWriteArraySet is a thread-safe collection and it internally uses CopyOnWriteArrayList for all of its operations.

Since it uses CopyOnWriteArrayList internally so thread-safety is achieved in the same way in CopyOnwriteArraySet as in CopyOnWriteArrayList - all mutative operations (add, set, and so on) are implemented by MAKING a fresh copy of the underlying array.

The ITERATOR returned by CopyOnwriteArraySet is fail-safe which means any STRUCTURAL modification made to the CopyOnwriteArraySet won't throw ConcurrentModificationException.

CopyOnWriteArraySet is a thread-safe collection and it internally uses CopyOnWriteArrayList for all of its operations.

Since it uses CopyOnWriteArrayList internally so thread-safety is achieved in the same way in CopyOnwriteArraySet as in CopyOnWriteArrayList - all mutative operations (add, set, and so on) are implemented by making a fresh copy of the underlying array.

The iterator returned by CopyOnwriteArraySet is fail-safe which means any structural modification made to the CopyOnwriteArraySet won't throw ConcurrentModificationException.