Question

Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop

TuteeHUB · Accepted Answer

{"id":131466,"user_id":8,"qa_id":94600,"answer_id":0,"answer":"_x000D_
Iterator.remove() is safe, you can use it like this:

List list = new ArrayList();

// This is a clever way to create the iterator and call iterator.hasNext() like
// you would do in a while-loop. It would be the same as doing:
//     Iterator iterator = list.iterator();
//     while (iterator.hasNext()) {
for (Iterator iterator = list.iterator(); iterator.hasNext();) {
    String string = iterator.next();
    if (string.isEmpty()) {
        // Remove the current element from the iterator and the list.
        iterator.remove();
    }
}

Note that Iterator.remove() is the only safe way to modify a collection during iteration; the behavior is unspecified if the underlying collection is modified in any other way while the iteration is in progress.

Source: docs.oracle > The Collection Interface

And similarly, if you have a ListIterator and want to add items, you can use ListIterator#add, for the same reason you can use Iterator#removeÂ â€” it's designed to allow it.

In your case you tried to remove from a list, but the same restriction applies if trying to put into a Map while iterating its content. 
    ","credit":0,"created_at":"2022-08-16T00:49:07.000000Z","updated_at":"2022-08-16T00:49:07.000000Z"}

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Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop

Manpreet Singh

Answers (1)

manpreet Best Answer 2 years ago

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