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The backing list (i.e., this list) is structurally modified inĪny way other than via the returned list. The semantics of the list returned by this method become undefined if LastIndexOf(Object), and all of the algorithms in theĬollections class can be applied to a subList. Similar idioms may be constructed for indexOf(Object) and Any operation that expectsĪ list can be used as a range operation by passing a subList view The sort that commonly exist for arrays). This method eliminates the need for explicit range operations (of The returned list supports all of the optional list operations. (IfįromIndex and toIndex are equal, the returned list isĮmpty.) The returned list is backed by this list, so non-structuralĬhanges in the returned list are reflected in this list, and vice-versa. Returns a view of the portion of this list between the specifiedįromIndex, inclusive, and toIndex, exclusive. This list NullPointerException - if the specified array is null Is not a supertype of the runtime type of every element in Returns: an array containing the elements of the list Throws: ArrayStoreException - if the runtime type of the specified array Same runtime type is allocated for this purpose. List only if the caller knows that the list does not containĪny null elements.) Specified by: toArray in interface Collection Specified by: toArray in interface List Overrides: toArray in class AbstractCollection Type Parameters: T - the component type of the array to contain the collection Parameters: a - the array into which the elements of the list are toīe stored, if it is big enough otherwise, a new array of the (This is useful in determining the length of the The array immediately following the end of the collection is set to (i.e., the array has more elements than the list), the element in If the list fits in the specified array with room to spare Otherwise, a new array isĪllocated with the runtime type of the specified array and the size of Sequence (from first to last element) the runtime type of the returnedĪrray is that of the specified array. Returns an array containing all of the elements in this list in proper Therefore, it would be wrong to write a program that depended on thisĮxception for its correctness: the fail-fast behavior of iterators Throw ConcurrentModificationException on a best-effort basis. Presence of unsynchronized concurrent modification. Note that the fail-fast behavior of an iterator cannot be guaranteedĪs it is, generally speaking, impossible to make any hard guarantees in the Than risking arbitrary, non-deterministic behavior at an undetermined Thus, in the face ofĬoncurrent modification, the iterator fails quickly and cleanly, rather If the list is structurally modified at any time after the iterator isĬreated, in any way except through the iterator's ownĬoncurrentModificationException. The iterators returned by this class's iterator and List list = Collections.synchronizedList(new ArrayList(.)) This is best done at creation time, to prevent accidental

If no such object exists, the list should be "wrapped" using the Synchronizing on some object that naturally encapsulates the list. Resizes the backing array merely setting the value of an element is notĪ structural modification.) This is typically accomplished by (A structural modification isĪny operation that adds or deletes one or more elements, or explicitly If multiple threads access an ArrayList instance concurrently,Īnd at least one of the threads modifies the list structurally, it Note that this implementation is not synchronized. This may reduce the amount of incremental reallocation. Specified beyond the fact that adding an element has constant amortizedĪn application can increase the capacity of an ArrayList instanceīefore adding a large number of elements using the ensureCapacity It is alwaysĪt least as large as the list size. The size of the array used to store the elements in the list. To that for the LinkedList implementation.Įach ArrayList instance has a capacity. That is, adding n elements requires O(n) time. The add operation runs in amortized constant time, Iterator, and listIterator operations run in constant Vector, except that it is unsynchronized.)

This class provides methods to manipulate the size of the array that is In addition to implementing the List interface, ImplementsĪll optional list operations, and permits all elements, including Resizable-array implementation of the List interface.