Iterator List Error "java.util.ConcurrentModificationException"

Question

Hi,
I'm with a problem. I've got a set of objects in a List. I'm iterating the list and during this process, I have to add more objects to the list. The system returns the exception "java.util.ConcurrentModificationException".
What is the solution to this problem, that is, how can I iterate a list, adding or removig elements without error
Thanx
MP

Answer 1

You cannot add to a list while iterators are in progress. You can remove elements by calling the remove method on the iterator.
If you need to both iterate and add, consider iterating a copy of the list, like so:
List copy = new ArrayList(originalList);
for (Iterator it = copy.iterator(); it.hasNext(); ) {
   // call originalList.add here
}You could also consider indexing into the list (if it's an ArrayList), and then "bumping" your indices as you add elements.