E - the type of elements held in this collectionpublic class ConcurrentLinkedDeque<E>
extends java.util.AbstractCollection<E>
implements java.util.Deque<E>, java.io.Serializable
Deque (double-ended queue).
This class should not be considered a part of the public API.
Concurrent insertion, removal, and access
operations execute safely across multiple threads. 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.
This class and its iterators implement all of the
optional methods of the Collection and Iterator interfaces. Like most other concurrent collection
implementations, this class does not permit the use of
null elements. because some null arguments and return
values cannot be reliably distinguished from the absence of
elements. Arbitrarily, the Collection.remove(java.lang.Object) method is
mapped to removeFirstOccurrence, and Collection.add(E) is mapped to addLast.
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.
This class is Serializable, but relies on default
serialization mechanisms. Usually, it is a better idea for any
serializable class using a ConcurrentLinkedDeque to instead
serialize a snapshot of the elements obtained by method
toArray.
| Modifier and Type | Class and Description |
|---|---|
static interface |
ConcurrentLinkedDeque.RemovalReportingIterator<E> |
| Constructor and Description |
|---|
ConcurrentLinkedDeque()
Constructs an empty deque.
|
ConcurrentLinkedDeque(java.util.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(java.util.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(java.lang.Object o)
Returns
true if this deque contains at least one
element e such that o.equals(e). |
java.util.Iterator<E> |
descendingIterator()
Not yet implemented.
|
E |
element() |
E |
getFirst() |
E |
getLast() |
boolean |
isEmpty()
Returns
true if this collection contains no elements. |
ConcurrentLinkedDeque.RemovalReportingIterator<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 queue.
|
boolean |
offerFirst(E e)
Inserts the specified element at the front of this deque.
|
boolean |
offerLast(E e)
Inserts the specified element at the end of this deque.
|
E |
peek() |
E |
peekFirst() |
E |
peekLast() |
E |
poll() |
E |
pollFirst() |
E |
pollLast() |
E |
pop() |
void |
push(E e) |
E |
remove() |
boolean |
remove(java.lang.Object o)
Removes the first element
e such that
o.equals(e), if such an element exists in this deque. |
E |
removeFirst() |
boolean |
removeFirstOccurrence(java.lang.Object o)
Removes the first element
e such that
o.equals(e), if such an element exists in this deque. |
E |
removeLast() |
boolean |
removeLastOccurrence(java.lang.Object o)
Removes the last element
e such that
o.equals(e), if such an element exists in this deque. |
int |
size()
Returns the number of elements in this deque.
|
java.lang.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.
|
containsAll, removeAll, retainAll, toStringequals, getClass, hashCode, notify, notifyAll, wait, wait, waitpublic ConcurrentLinkedDeque()
public ConcurrentLinkedDeque(java.util.Collection<? extends E> c)
c - the collection of elements to initially containjava.lang.NullPointerException - if the specified collection or any
of its elements are nullpublic void addFirst(E e)
addFirst in interface java.util.Deque<E>java.lang.NullPointerExceptionpublic void addLast(E e)
add method.addLast in interface java.util.Deque<E>java.lang.NullPointerExceptionpublic boolean offerFirst(E e)
offerFirst in interface java.util.Deque<E>true alwaysjava.lang.NullPointerExceptionpublic boolean offerLast(E e)
This method is equivalent to add(E).
offerLast in interface java.util.Deque<E>true alwaysjava.lang.NullPointerExceptionpublic E getFirst()
getFirst in interface java.util.Deque<E>java.util.NoSuchElementExceptionpublic E getLast()
getLast in interface java.util.Deque<E>java.util.NoSuchElementExceptionpublic E removeFirst()
removeFirst in interface java.util.Deque<E>java.util.NoSuchElementExceptionpublic E removeLast()
removeLast in interface java.util.Deque<E>java.util.NoSuchElementExceptionpublic boolean offer(E e)
public boolean add(E e)
add in interface java.util.Collection<E>add in interface java.util.Deque<E>add in interface java.util.Queue<E>add in class java.util.AbstractCollection<E>true (as specified by Collection.add(E))java.lang.NullPointerException - if the specified element is nullpublic E poll()
public E remove()
public E peek()
public E element()
public boolean removeFirstOccurrence(java.lang.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 java.util.Deque<E>o - element to be removed from this deque, if presenttrue if the deque contained the specified elementjava.lang.NullPointerException - if the specified element is nullpublic boolean removeLastOccurrence(java.lang.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 java.util.Deque<E>o - element to be removed from this deque, if presenttrue if the deque contained the specified elementjava.lang.NullPointerException - if the specified element is nullpublic boolean contains(java.lang.Object o)
true if this deque contains at least one
element e such that o.equals(e).contains in interface java.util.Collection<E>contains in interface java.util.Deque<E>contains in class java.util.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.public 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.
public boolean remove(java.lang.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 java.util.Collection<E>remove in interface java.util.Deque<E>remove in class java.util.AbstractCollection<E>o - element to be removed from this deque, if presenttrue if the deque contained the specified elementjava.lang.NullPointerException - if the specified element is nullpublic boolean addAll(java.util.Collection<? extends E> c)
addAll in interface java.util.Collection<E>addAll in class java.util.AbstractCollection<E>c - the elements to be inserted into this dequetrue if this deque changed as a result of the calljava.lang.NullPointerException - if c or any element within it
is nullpublic void clear()
public java.lang.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.
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 java.util.Collection<E>toArray in class java.util.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 purposejava.lang.ArrayStoreException - if the runtime type of the specified array
is not a supertype of the runtime type of every element in
this dequejava.lang.NullPointerException - if the specified array is nullpublic ConcurrentLinkedDeque.RemovalReportingIterator<E> iterator()
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.iterator in interface java.lang.Iterable<E>iterator in interface java.util.Collection<E>iterator in interface java.util.Deque<E>iterator in class java.util.AbstractCollection<E>Copyright © 2010 - 2020 Adobe. All Rights Reserved