Concurrent Modification exception

Question

I have this little piece of code and it gives me the concurrent modification exception. I cannot understand why I keep getting it, even though I do not see any concurrent mo

Answer 1

You are not allowed to continue iterating over an iterator after the underlying list is modified. Here you create the iterator before adding a few items to s, and then proceed to do a hasNext() and a next() on it after the additions, leading to the ConcurrentModificationException