Re: Collection implementations and fail-fast iterator problems.

"Mike Schilling" <>
Sat, 03 Nov 2007 00:53:56 GMT
Daniel Pitts wrote:

Eric Sosman wrote:

Daniel Pitts wrote On 11/02/07 17:06,:

I have a simulation where I visit every element in a Collection. While
visiting these, I may find out that I want to add a new
element, or remove some later-occurring element before I get to it.
I have a few Collections like this.

I'd like to avoid having to keep track of "to-be-deleted" and
"to-be-added" elements, but I don't see an elegant way to handle
both those cases without getting a ConcurrentModificationError.


    If your Collection implements List, perhaps you could
use a ListIterator.

How does that help? Adding and Removing STILL causes concurrent
modification errors, does it not?

The ConcurrentModificationException means "I'm an iterator and, oh crap,
someone's modified the collection behind my back and now I can't do my job."
Modifying the collection with the iterator's knowledge (that is, by using
the iterator) won't cause this problem.

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