Why Am I Getting ConcurrentModificationException in a Synchronized Method?

ConcurrentModificationException in Synchronized Method: Unraveling the Confusion

In a synchronized method like the one provided, the ConcurrentModificationException exception can arise even with the synchronized modifier. This exception usually results from modifying the collection being iterated over within the iteration loop.

The issue here is that synchronizing the method doesn't guarantee that the collection will not be modified while iteration is occurring. To prevent this exception, it's imperative to avoid modifying the collection during iteration.

A typical example of a code snippet that would trigger this exception is:

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

Instead, the code should use the iterator.remove() method to remove items from the collection during iteration. If additions to the collection are necessary, the ListIterator subtype can be utilized as it provides an add() method when dealing with a list.

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