ConcurrentModificationException for ArrayList [duplicate]

Answer 1

Like the other answers say, you can't remove an item from a collection you're iterating over. You can get around this by explicitly using an Iterator and removing the item there.

Iterator iter = list.iterator();
while(iter.hasNext()) {
  Item blah = iter.next();
  if(...) {
    iter.remove(); // Removes the 'current' item
  }
}