Copy on write arraylist java

A thread-safe variant of ArrayList in which all mutative operations ( add , set , and so on) are implemented by making a fresh copy of the underlying array. This is ordinarily too costly, but may be more efficient than alternatives when traversal operations vastly outnumber mutations, and is useful when you cannot or don’t want to synchronize traversals, yet need to preclude interference among concurrent threads. The «snapshot» style iterator method uses a reference to the state of the array at the point that the iterator was created. This array never changes during the lifetime of the iterator, so interference is impossible and the iterator is guaranteed not to throw ConcurrentModificationException . The iterator will not reflect additions, removals, or changes to the list since the iterator was created. Element-changing operations on iterators themselves ( remove , set , and add ) are not supported. These methods throw UnsupportedOperationException . All elements are permitted, including null . Memory consistency effects: As with other concurrent collections, actions in a thread prior to placing an object into a CopyOnWriteArrayList happen-before actions subsequent to the access or removal of that element from the CopyOnWriteArrayList in another thread. This class is a member of the Java Collections Framework.

Constructor Summary

Creates a list containing the elements of the specified collection, in the order they are returned by the collection’s iterator.

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Method Summary

Appends all of the elements in the specified collection to the end of this list, in the order that they are returned by the specified collection’s iterator.

Inserts all of the elements in the specified collection into this list, starting at the specified position.

Appends all of the elements in the specified collection that are not already contained in this list, to the end of this list, in the order that they are returned by the specified collection’s iterator.

Performs the given action for each element of the Iterable until all elements have been processed or the action throws an exception.

Returns the index of the first occurrence of the specified element in this list, searching forwards from index , or returns -1 if the element is not found.

Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.

Returns the index of the last occurrence of the specified element in this list, searching backwards from index , or returns -1 if the element is not found.

Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.

Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list.

Returns an array containing all of the elements in this list in proper sequence (from first to last element).

Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array.

Источник

Class CopyOnWriteArrayList

A thread-safe variant of ArrayList in which all mutative operations ( add , set , and so on) are implemented by making a fresh copy of the underlying array.

This is ordinarily too costly, but may be more efficient than alternatives when traversal operations vastly outnumber mutations, and is useful when you cannot or don’t want to synchronize traversals, yet need to preclude interference among concurrent threads. The «snapshot» style iterator method uses a reference to the state of the array at the point that the iterator was created. This array never changes during the lifetime of the iterator, so interference is impossible and the iterator is guaranteed not to throw ConcurrentModificationException . The iterator will not reflect additions, removals, or changes to the list since the iterator was created. Element-changing operations on iterators themselves ( remove , set , and add ) are not supported. These methods throw UnsupportedOperationException .

All elements are permitted, including null .

Memory consistency effects: As with other concurrent collections, actions in a thread prior to placing an object into a CopyOnWriteArrayList happen-before actions subsequent to the access or removal of that element from the CopyOnWriteArrayList in another thread.

This class is a member of the Java Collections Framework.