(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 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.
API Note
This interface does not impose any requirements on the equals and hashCode
methods, because requirements imposed by sub-interfaces List and SequencedSet
(which inherits requirements from Set) would be in conflict. See the specifications for
Collection. and Collection.
for further information.
| Modifier and Type | Method and Description |
|---|---|
| public default void | addFirst(E
the element to be added e)Adds an element as the first element of this collection (optional operation). |
| public default void | addLast(E
the element to be added. e)Adds an element as the last element of this collection (optional operation). |
| public default E | |
| public default E | |
| public default E | Returns: the removed elementRemoves and returns the first element of this collection (optional operation). |
| public default E | Returns: the removed elementRemoves and returns the last element of this collection (optional operation). |
| public SequencedCollection |
| addFirst | back to summary |
|---|---|
| public default void addFirst(E e) 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. Implementation Specification The implementation in this interface always throws
| |
| addLast | back to summary |
|---|---|
| public default void addLast(E e) 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. Implementation Specification The implementation in this interface always throws
| |
| getFirst | back to summary |
|---|---|
| public default E getFirst() Gets the first element of this collection. Implementation Specification The implementation in this interface obtains an iterator of this collection, and
then it obtains an element by calling the iterator's
| |
| getLast | back to summary |
|---|---|
| public default E getLast() Gets the last element of this collection. Implementation Specification The implementation in this interface obtains an iterator of the reversed view
of this collection, and then it obtains an element by calling the iterator's
| |
| removeFirst | back to summary |
|---|---|
| public default E removeFirst() Removes and returns the first element of this collection (optional operation). Implementation Specification The implementation in this interface obtains an iterator of this collection, and then
it obtains an element by calling the iterator's
| |
| removeLast | back to summary |
|---|---|
| public default E removeLast() Removes and returns the last element of this collection (optional operation). Implementation Specification The implementation in this interface obtains an iterator of the reversed view of this
collection, and then it obtains an element by calling the iterator's
| |
| reversed | back to summary |
|---|---|
| public SequencedCollection 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.
| |
