What is fail-fast iterators ?

Can anybody please clarify what does it exactly mean by fail-fast iterator. I had even gone through the entire API which says about this . but coudn't make it out

[170 byte] By [raja.datlaa] at [2007-11-27 11:29:41]
# 1

http://java.sun.com/j2se/1.5.0/docs/guide/collections/overview.html

ejpa at 2007-7-29 16:29:25 > top of Java-index,Core,Core APIs...
# 2

It's an iterator that will throw an exception if something else tries to edit the collection it's iterating through. Namely a concurrentModificationException. This is a good thing because it will mess up a lot worse, later, if this type of thing isn't picked up. Hope that helps.

RedUnderTheBeda at 2007-7-29 16:29:25 > top of Java-index,Core,Core APIs...