Here is an example of a ConcurrentModificationException thrown when attempting to remove an element from an ArrayList using the remove() method while traversing it using an enhanced for loop: import java.util. Single-threaded environment - When an element is attempted to be removed from an ArrayList using the remove() method while it is being traversed using an enhanced for loop.Multithreaded environment - If a thread is traversing over a Collection using an Iterator and another thread attempts to add or remove elements to the Collection.This exception can occur in both multithreaded and single-threaded Java environments. As others have mentioned, movies.clear() is the simplest way to empty the movies list. 2.1 removeIf examples 2.2 removeIf uses Iterator 3. This article shows a few ways to solve it. Each time through the loop, index increases by 1, and tempMovieSize also increases by 1. In Java, if we remove items from a List while iterating it, it will throw. Usage would be: list1.retainAll (list2) It might not be any more efficient than a naive iteration approach, however, unless you use Set. Your second attempt is even more problematic. In other words, removes from this collection all of its elements that are not contained in the specified collection. The Collection classes in Java are very fail-fast and if they are attempted to be modified while a thread is iterating over it, a ConcurrentModificationException is thrown. Retains only the elements in this collection that are contained in the specified collection. The ConcurrentModificationException generally occurs when working with Java Collections. What Causes ConcurrentModificationException The ConcurrentModificationException can occur in both multithreaded and single-threaded environments. So far, I've got three total ways I've coded. Note that this means you cant use the enhanced for loop. For example, if a Collection is modified while a thread is traversing it using an Iterator, a ConcurrentModificationException is thrown from the Iterator.next() method. 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. This exception occurs when an object is attempted to be modified concurrently without permission. The ConcurrentModificationException is used to fail-fast when something being iterated on is modified. I want to remove an object from a list, but I have a thread that is consistently checking the same list using an iterator. If it's the latter, make sure to get a new iterator from the entry set. Either wait until the iterator is 'on' the entry you want to remove and use Iterator.remove (), or do it outside of (before/after) the iteration loop. The ConcurrentModificationException is a very common exception in Java that occurs usually while working with Collections. If you use any remove method other than Iterator.remove () during iteration, the results of the iteration are undefined.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |