Why Do I Get a ConcurrentModificationException Even When Using Synchronized?

ConcurrentModificationException when Using Synchronized

Despite synchronizing the getAnotherX method, you're encountering a ConcurrentModificationException exception when calling iterator.next(). To understand why this occurs, it's crucial to comprehend the nature of the ConcurrentModificationException.

Nature of ConcurrentModificationException

Contrary to its name, ConcurrentModificationException is not primarily caused by multiple threads. It often arises when modifying the collection being iterated over within the iteration loop. Here's an example:

Iterator iterator = collection.iterator();
while (iterator.hasNext()) {
    Item item = (Item) iterator.next();
    if (item.satisfiesCondition()) {
       collection.remove(item);
    }
}

In this scenario, using iterator.remove() instead of collection.remove(item) is essential. This exception can also occur when adding to the collection. Unfortunately, there's no general solution for this case. However, if you're dealing with a List, you can use ListIterator, which has an add() method.

The above is the detailed content of Why Do I Get a ConcurrentModificationException Even When Using Synchronized?. For more information, please follow other related articles on the PHP Chinese website!