How to avoid java.util.ConcurrentModificationException when iterating through and removing elements from an ArrayList

Two options:

  • Create a list of values you wish to remove, adding to that list within the loop, then call originalList.removeAll(valuesToRemove) at the end
  • Use the remove() method on the iterator itself. Note that this means you can’t use the enhanced for loop.

As an example of the second option, removing any strings with a length greater than 5 from a list:

List<String> list = new ArrayList<String>();
for (Iterator<String> iterator = list.iterator(); iterator.hasNext(); ) {
    String value =;
    if (value.length() > 5) {

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