E - the type of elements held in this collectionpublic class PortableConcurrentDirectDeque<E> extends ConcurrentDirectDeque<E> implements Deque<E>, Serializable
ConcurrentLinkedDeque is an appropriate choice when
many threads will share access to a common collection.
Like most other concurrent collection implementations, this class
does not permit the use of null elements.
Iterators are weakly consistent, returning elements
reflecting the state of the deque at some point at or since the
creation of the iterator. They do not throw ConcurrentModificationException, and may proceed concurrently with
other operations.
Beware that, unlike in most collections, the size method
is NOT a constant-time operation. Because of the
asynchronous nature of these deques, determining the current number
of elements requires a traversal of the elements, and so may report
inaccurate results if this collection is modified during traversal.
Additionally, the bulk operations addAll,
removeAll, retainAll, containsAll,
equals, and toArray are not guaranteed
to be performed atomically. For example, an iterator operating
concurrently with an addAll operation might view only some
of the added elements.
This class and its iterator implement all of the optional
methods of the Deque and Iterator interfaces.
Memory consistency effects: As with other concurrent collections,
actions in a thread prior to placing an object into a
ConcurrentLinkedDeque
happen-before
actions subsequent to the access or removal of that element from
the ConcurrentLinkedDeque in another thread.
This class is a member of the Java Collections Framework.
| Constructor and Description |
|---|
PortableConcurrentDirectDeque()
Constructs an empty deque.
|
PortableConcurrentDirectDeque(Collection<? extends E> c)
Constructs a deque initially containing the elements of
the given collection, added in traversal order of the
collection's iterator.
|
| Modifier and Type | Method and Description |
|---|---|
boolean |
add(E e)
Inserts the specified element at the tail of this deque.
|
boolean |
addAll(Collection<? extends E> c)
Appends all of the elements in the specified collection to the end of
this deque, in the order that they are returned by the specified
collection's iterator.
|
void |
addFirst(E e)
Inserts the specified element at the front of this deque.
|
void |
addLast(E e)
Inserts the specified element at the end of this deque.
|
void |
clear()
Removes all of the elements from this deque.
|
boolean |
contains(Object o)
Returns
true if this deque contains at least one
element e such that o.equals(e). |
Iterator<E> |
descendingIterator()
Returns an iterator over the elements in this deque in reverse
sequential order.
|
E |
element() |
E |
getFirst() |
E |
getLast() |
boolean |
isEmpty()
Returns
true if this collection contains no elements. |
Iterator<E> |
iterator()
Returns an iterator over the elements in this deque in proper sequence.
|
boolean |
offer(E e)
Inserts the specified element at the tail of this deque.
|
boolean |
offerFirst(E e)
Inserts the specified element at the front of this deque.
|
Object |
offerFirstAndReturnToken(E e) |
boolean |
offerLast(E e)
Inserts the specified element at the end of this deque.
|
Object |
offerLastAndReturnToken(E e) |
E |
peek() |
E |
peekFirst() |
E |
peekLast() |
E |
poll() |
E |
pollFirst() |
E |
pollLast() |
E |
pop() |
void |
push(E e) |
E |
remove() |
boolean |
remove(Object o)
Removes the first element
e such that
o.equals(e), if such an element exists in this deque. |
E |
removeFirst() |
boolean |
removeFirstOccurrence(Object o)
Removes the first element
e such that
o.equals(e), if such an element exists in this deque. |
E |
removeLast() |
boolean |
removeLastOccurrence(Object o)
Removes the last element
e such that
o.equals(e), if such an element exists in this deque. |
void |
removeToken(Object token) |
int |
size()
Returns the number of elements in this deque.
|
Object[] |
toArray()
Returns an array containing all of the elements in this deque, in
proper sequence (from first to last element).
|
<T> T[] |
toArray(T[] a)
Returns an array containing all of the elements in this deque,
in proper sequence (from first to last element); the runtime
type of the returned array is that of the specified array.
|
newInstancecontainsAll, removeAll, retainAll, toStringclone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitcontainsAll, equals, hashCode, parallelStream, removeAll, removeIf, retainAll, spliterator, streampublic PortableConcurrentDirectDeque()
public PortableConcurrentDirectDeque(Collection<? extends E> c)
c - the collection of elements to initially containNullPointerException - if the specified collection or any
of its elements are nullpublic void addFirst(E e)
IllegalStateException.addFirst in interface Deque<E>NullPointerException - if the specified element is nullpublic void addLast(E e)
IllegalStateException.
This method is equivalent to add(E).
addLast in interface Deque<E>NullPointerException - if the specified element is nullpublic boolean offerFirst(E e)
false.offerFirst in interface Deque<E>true (as specified by Deque.offerFirst(E))NullPointerException - if the specified element is nullpublic Object offerFirstAndReturnToken(E e)
offerFirstAndReturnToken in class ConcurrentDirectDeque<E>public Object offerLastAndReturnToken(E e)
offerLastAndReturnToken in class ConcurrentDirectDeque<E>public void removeToken(Object token)
removeToken in class ConcurrentDirectDeque<E>public boolean offerLast(E e)
false.
This method is equivalent to add(E).
offerLast in interface Deque<E>true (as specified by Deque.offerLast(E))NullPointerException - if the specified element is nullpublic E getFirst()
getFirst in interface Deque<E>NoSuchElementExceptionpublic E getLast()
getLast in interface Deque<E>NoSuchElementExceptionpublic E removeFirst()
removeFirst in interface Deque<E>NoSuchElementExceptionpublic E removeLast()
removeLast in interface Deque<E>NoSuchElementExceptionpublic boolean offer(E e)
false.offer in interface Deque<E>offer in interface Queue<E>true (as specified by Queue.offer(E))NullPointerException - if the specified element is nullpublic boolean add(E e)
IllegalStateException or return false.add in interface Collection<E>add in interface Deque<E>add in interface Queue<E>add in class AbstractCollection<E>true (as specified by Collection.add(E))NullPointerException - if the specified element is nullpublic E poll()
public E remove()
public E peek()
public E element()
public boolean removeFirstOccurrence(Object o)
e such that
o.equals(e), if such an element exists in this deque.
If the deque does not contain the element, it is unchanged.removeFirstOccurrence in interface Deque<E>o - element to be removed from this deque, if presenttrue if the deque contained the specified elementNullPointerException - if the specified element is nullpublic boolean removeLastOccurrence(Object o)
e such that
o.equals(e), if such an element exists in this deque.
If the deque does not contain the element, it is unchanged.removeLastOccurrence in interface Deque<E>o - element to be removed from this deque, if presenttrue if the deque contained the specified elementNullPointerException - if the specified element is nullpublic boolean contains(Object o)
true if this deque contains at least one
element e such that o.equals(e).contains in interface Collection<E>contains in interface Deque<E>contains in class AbstractCollection<E>o - element whose presence in this deque is to be testedtrue if this deque contains the specified elementpublic boolean isEmpty()
true if this collection contains no elements.isEmpty in interface Collection<E>isEmpty in class AbstractCollection<E>true if this collection contains no elementspublic int size()
Integer.MAX_VALUE elements, it
returns Integer.MAX_VALUE.
Beware that, unlike in most collections, this method is NOT a constant-time operation. Because of the asynchronous nature of these deques, determining the current number of elements requires traversing them all to count them. Additionally, it is possible for the size to change during execution of this method, in which case the returned result will be inaccurate. Thus, this method is typically not very useful in concurrent applications.
size in interface Collection<E>size in interface Deque<E>size in class AbstractCollection<E>public boolean remove(Object o)
e such that
o.equals(e), if such an element exists in this deque.
If the deque does not contain the element, it is unchanged.remove in interface Collection<E>remove in interface Deque<E>remove in class AbstractCollection<E>o - element to be removed from this deque, if presenttrue if the deque contained the specified elementNullPointerException - if the specified element is nullpublic boolean addAll(Collection<? extends E> c)
addAll of a deque to
itself result in IllegalArgumentException.addAll in interface Collection<E>addAll in class AbstractCollection<E>c - the elements to be inserted into this dequetrue if this deque changed as a result of the callNullPointerException - if the specified collection or any
of its elements are nullIllegalArgumentException - if the collection is this dequepublic void clear()
clear in interface Collection<E>clear in class AbstractCollection<E>public Object[] toArray()
The returned array will be "safe" in that no references to it are maintained by this deque. (In other words, this method must allocate a new array). The caller is thus free to modify the returned array.
This method acts as bridge between array-based and collection-based APIs.
toArray in interface Collection<E>toArray in class AbstractCollection<E>public <T> T[] toArray(T[] a)
If this deque fits in the specified array with room to spare
(i.e., the array has more elements than this deque), the element in
the array immediately following the end of the deque is set to
null.
Like the toArray() method, this method acts as
bridge between array-based and collection-based APIs. Further,
this method allows precise control over the runtime type of the
output array, and may, under certain circumstances, be used to
save allocation costs.
Suppose x is a deque known to contain only strings.
The following code can be used to dump the deque into a newly
allocated array of String:
String[] y = x.toArray(new String[0]);
Note that toArray(new Object[0]) is identical in function to
toArray().toArray in interface Collection<E>toArray in class AbstractCollection<E>a - the array into which the elements of the deque are to
be stored, if it is big enough; otherwise, a new array of the
same runtime type is allocated for this purposeArrayStoreException - if the runtime type of the specified array
is not a supertype of the runtime type of every element in
this dequeNullPointerException - if the specified array is nullpublic Iterator<E> iterator()
The returned iterator is a "weakly consistent" iterator that
will never throw ConcurrentModificationException, and guarantees to traverse
elements as they existed upon construction of the iterator, and
may (but is not guaranteed to) reflect any modifications
subsequent to construction.
public Iterator<E> descendingIterator()
The returned iterator is a "weakly consistent" iterator that
will never throw ConcurrentModificationException, and guarantees to traverse
elements as they existed upon construction of the iterator, and
may (but is not guaranteed to) reflect any modifications
subsequent to construction.
descendingIterator in interface Deque<E>Copyright © 2025 JBoss by Red Hat. All rights reserved.