SequencedCollection
interface SequencedCollection<E : Any!> : MutableCollection<E>
| java.util.SequencedCollection |
A collection that has a well-defined encounter order, that supports operations at both ends, and that is reversible. The elements of a sequenced collection have an encounter order, where conceptually the elements have a linear arrangement from the first element to the last element. Given any two elements, one element is either before (closer to the first element) or after (closer to the last element) the other element.
(Note that this definition does not imply anything about physical positioning of elements, such as their locations in a computer's memory.)
Several methods inherited from the Collection interface are required to operate on elements according to this collection's encounter order. For instance, the iterator method provides elements starting from the first element, proceeding through successive elements, until the last element. Other methods that are required to operate on elements in encounter order include the following: forEach, parallelStream, spliterator, stream, and all overloads of the java.util.Collection#toArray method.
This interface provides methods to add, retrieve, and remove elements at either end of the collection.
This interface also defines the reversed method, which provides a reverse-ordered view of this collection. In the reverse-ordered view, the concepts of first and last are inverted, as are the concepts of successor and predecessor. The first element of this collection is the last element of the reverse-ordered view, and vice-versa. The successor of some element in this collection is its predecessor in the reversed view, and vice-versa. All methods that respect the encounter order of the collection operate as if the encounter order is inverted. For instance, the iterator method of the reversed view reports the elements in order from the last element of this collection to the first. The availability of the reversed method, and its impact on the ordering semantics of all applicable methods, allow convenient iteration, searching, copying, and streaming of the elements of this collection in either forward order or reverse order.
This class is a member of the Java Collections Framework.
Summary
| Public methods | |
|---|---|
| open Unit |
addFirst(e: E)Adds an element as the first element of this collection (optional operation). |
| open Unit |
addLast(e: E)Adds an element as the last element of this collection (optional operation). |
| open E |
getFirst()Gets the first element of this collection. |
| open E |
getLast()Gets the last element of this collection. |
| open E |
Removes and returns the first element of this collection (optional operation). |
| open E |
Removes and returns the last element of this collection (optional operation). |
| abstract SequencedCollection<E>! |
reversed()Returns a reverse-ordered view of this collection. |
Public methods
addFirst
open fun addFirst(e: E): Unit
Adds an element as the first element of this collection (optional operation). After this operation completes normally, the given element will be a member of this collection, and it will be the first element in encounter order.
| Parameters | |
|---|---|
e |
E: the element to be added |
| Exceptions | |
|---|---|
java.lang.NullPointerException |
if the specified element is null and this collection does not permit null elements |
java.lang.UnsupportedOperationException |
if this collection implementation does not support this operation |
addLast
open fun addLast(e: E): Unit
Adds an element as the last element of this collection (optional operation). After this operation completes normally, the given element will be a member of this collection, and it will be the last element in encounter order.
| Parameters | |
|---|---|
e |
E: the element to be added. |
| Exceptions | |
|---|---|
java.lang.NullPointerException |
if the specified element is null and this collection does not permit null elements |
java.lang.UnsupportedOperationException |
if this collection implementation does not support this operation |
getFirst
open fun getFirst(): E
Gets the first element of this collection.
| Return | |
|---|---|
E |
the retrieved element |
| Exceptions | |
|---|---|
java.util.NoSuchElementException |
if this collection is empty |
getLast
open fun getLast(): E
Gets the last element of this collection.
| Return | |
|---|---|
E |
the retrieved element |
| Exceptions | |
|---|---|
java.util.NoSuchElementException |
if this collection is empty |
removeFirst
open fun removeFirst(): E
Removes and returns the first element of this collection (optional operation).
| Return | |
|---|---|
E |
the removed element |
| Exceptions | |
|---|---|
java.util.NoSuchElementException |
if this collection is empty |
java.lang.UnsupportedOperationException |
if this collection implementation does not support this operation |
removeLast
open fun removeLast(): E
Removes and returns the last element of this collection (optional operation).
| Return | |
|---|---|
E |
the removed element |
| Exceptions | |
|---|---|
java.util.NoSuchElementException |
if this collection is empty |
java.lang.UnsupportedOperationException |
if this collection implementation does not support this operation |
reversed
abstract fun reversed(): SequencedCollection<E>!
Returns a reverse-ordered view of this collection. The encounter order of elements in the returned view is the inverse of the encounter order of elements in this collection. The reverse ordering affects all order-sensitive operations, including those on the view collections of the returned view. If the collection implementation permits modifications to this view, the modifications "write through" to the underlying collection. Changes to the underlying collection might or might not be visible in this reversed view, depending upon the implementation.
| Return | |
|---|---|
SequencedCollection<E>! |
a reverse-ordered view of this collection |