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java.lang.Object
java.util.AbstractCollection<E>
java.util.AbstractQueue<E>
java.util.concurrent.LinkedBlockingDeque<E>
public class LinkedBlockingDeque<E>
extends AbstractQueue<E>
implements BlockingDeque<E>, Serializable
Integer.MAX_VALUE
. Linked nodes are
dynamically created upon each insertion unless this would bring the
deque above capacity.
Most operations run in constant time (ignoring time spent
blocking). Exceptions include remove
,
removeFirstOccurrence
, removeLastOccurrence
, contains
, iterator.remove()
, and the bulk
operations, all of which run in linear time.
This class and its iterator implement all of the
optional methods of the Collection
and Iterator
interfaces.
This class is a member of the
../../../../technotes/guides/collections/index.html">
Java Collections Framework.
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Methods inherited from class java.util.AbstractCollection<E> | |
T[] toArray , add , addAll , clear , contains , containsAll , isEmpty , iterator , remove , removeAll , retainAll , size , toArray , toString |
Methods inherited from class java.lang.Object | |
clone , equals , extends Object> getClass , finalize , hashCode , notify , notifyAll , toString , wait , wait , wait |
public LinkedBlockingDeque()
Creates a LinkedBlockingDeque with a capacity ofInteger.MAX_VALUE
.
public LinkedBlockingDeque(E> c)
Creates a LinkedBlockingDeque with a capacity ofInteger.MAX_VALUE
, initially containing the elements of the given collection, added in traversal order of the collection's iterator.
- Parameters:
c
- the collection of elements to initially contain
- Throws:
NullPointerException
- if the specified collection or any of its elements are null
public LinkedBlockingDeque(int capacity)
Creates a LinkedBlockingDeque with the given (fixed) capacity.
- Parameters:
capacity
- the capacity of this deque
- Throws:
IllegalArgumentException
- if capacity is less than 1
publicT[] toArray(T[] a)
Returns an array containing all of the elements in this deque, in proper sequence; the runtime type of the returned array is that of the specified array. If the deque fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this deque. 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 thetoArray()
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().
- Specified by:
- T[] toArray in interface Collection<E>
- Overrides:
- T[] toArray in interface AbstractCollection<E>
- Parameters:
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 purpose
- Returns:
- an array containing all of the elements in this deque
- Throws:
ArrayStoreException
- 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 null
public boolean add(E e)
Inserts the specified element at the end of this deque unless it would violate capacity restrictions. When using a capacity-restricted deque, it is generally preferable to use methodoffer
. This method is equivalent toaddLast(E)
.
- Specified by:
- add in interface BlockingDeque<E>
- add in interface BlockingQueue<E>
- add in interface Queue<E>
- add in interface Collection<E>
- add in interface Deque<E>
- Overrides:
- add in interface AbstractQueue<E>
- Throws:
IllegalStateException
- if the element cannot be added at this time due to capacity restrictionsNullPointerException
- if the specified element is null
public void addFirst(E e)
- Specified by:
- addFirst in interface BlockingDeque<E>
- addFirst in interface Deque<E>
- Throws:
IllegalStateException
-NullPointerException
-
public void addLast(E e)
- Specified by:
- addLast in interface BlockingDeque<E>
- addLast in interface Deque<E>
- Throws:
IllegalStateException
-NullPointerException
-
public void clear()
Atomically removes all of the elements from this deque. The deque will be empty after this call returns.
- Specified by:
- clear in interface Collection<E>
- Overrides:
- clear in interface AbstractQueue<E>
public boolean contains(Object o)
Returns true if this deque contains the specified element. More formally, returns true if and only if this deque contains at least one element e such that o.equals(e).
- Specified by:
- contains in interface BlockingDeque<E>
- contains in interface BlockingQueue<E>
- contains in interface Collection<E>
- contains in interface Deque<E>
- Overrides:
- contains in interface AbstractCollection<E>
- Parameters:
o
- object to be checked for containment in this deque
- Returns:
- true if this deque contains the specified element
public IteratordescendingIterator()
Returns an iterator over the elements in this deque in reverse sequential order. The elements will be returned in order from last (tail) to first (head). The returned Iterator is a "weakly consistent" iterator that will never throwConcurrentModificationException
, 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.
- Specified by:
- descendingIterator in interface Deque<E>
public E element()
Retrieves, but does not remove, the head of the queue represented by this deque. This method differs frompeek
only in that it throws an exception if this deque is empty. This method is equivalent togetFirst
.
- Specified by:
- element in interface BlockingDeque<E>
- element in interface Queue<E>
- element in interface Deque<E>
- Overrides:
- element in interface AbstractQueue<E>
- Returns:
- the head of the queue represented by this deque
- Throws:
NoSuchElementException
- if this deque is empty
public Iteratoriterator()
Returns an iterator over the elements in this deque in proper sequence. The elements will be returned in order from first (head) to last (tail). The returned Iterator is a "weakly consistent" iterator that will never throwConcurrentModificationException
, 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.
- Specified by:
- iterator in interface BlockingDeque<E>
- iterator in interface Collection<E>
- iterator in interface Iterable<E>
- iterator in interface Deque<E>
- Overrides:
- iterator in interface AbstractCollection<E>
- Returns:
- an iterator over the elements in this deque in proper sequence
public boolean offer(E e)
- Specified by:
- offer in interface BlockingDeque<E>
- offer in interface BlockingQueue<E>
- offer in interface Queue<E>
- offer in interface Deque<E>
- Throws:
NullPointerException
- if the specified element is null
public boolean offer(E e, long timeout, TimeUnit unit) throws InterruptedException
- Specified by:
- offer in interface BlockingDeque<E>
- offer in interface BlockingQueue<E>
- Throws:
NullPointerException
-InterruptedException
-
public boolean offerFirst(E e)
- Specified by:
- offerFirst in interface BlockingDeque<E>
- offerFirst in interface Deque<E>
- Throws:
NullPointerException
-
public boolean offerFirst(E e, long timeout, TimeUnit unit) throws InterruptedException
- Specified by:
- offerFirst in interface BlockingDeque<E>
- Throws:
NullPointerException
-InterruptedException
-
public boolean offerLast(E e)
- Specified by:
- offerLast in interface BlockingDeque<E>
- offerLast in interface Deque<E>
- Throws:
NullPointerException
-
public boolean offerLast(E e, long timeout, TimeUnit unit) throws InterruptedException
- Specified by:
- offerLast in interface BlockingDeque<E>
- Throws:
NullPointerException
-InterruptedException
-
public E peek()
Retrieves, but does not remove, the head of the queue represented by this deque (in other words, the first element of this deque), or returns null if this deque is empty. This method is equivalent toDeque.peekFirst()
.
- Returns:
- the head of the queue represented by this deque, or null if this deque is empty
public E peekFirst()
Retrieves, but does not remove, the first element of this deque, or returns null if this deque is empty.
- Returns:
- the head of this deque, or null if this deque is empty
public E peekLast()
Retrieves, but does not remove, the last element of this deque, or returns null if this deque is empty.
- Returns:
- the tail of this deque, or null if this deque is empty
public E poll()
Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), or returns null if this deque is empty. This method is equivalent toDeque.pollFirst()
.
- Returns:
- the first element of this deque, or null if this deque is empty
public E poll(long timeout, TimeUnit unit) throws InterruptedException
- Specified by:
- poll in interface BlockingDeque<E>
- poll in interface BlockingQueue<E>
public E pollFirst()
Retrieves and removes the first element of this deque, or returns null if this deque is empty.
- Returns:
- the head of this deque, or null if this deque is empty
public E pollFirst(long timeout, TimeUnit unit) throws InterruptedException
- Specified by:
- pollFirst in interface BlockingDeque<E>
public E pollLast()
Retrieves and removes the last element of this deque, or returns null if this deque is empty.
- Returns:
- the tail of this deque, or null if this deque is empty
public E pollLast(long timeout, TimeUnit unit) throws InterruptedException
- Specified by:
- pollLast in interface BlockingDeque<E>
public void push(E e)
- Specified by:
- push in interface BlockingDeque<E>
- push in interface Deque<E>
- Throws:
IllegalStateException
-NullPointerException
-
public void put(E e) throws InterruptedException
- Specified by:
- put in interface BlockingDeque<E>
- put in interface BlockingQueue<E>
- Throws:
NullPointerException
-InterruptedException
-
public void putFirst(E e) throws InterruptedException
- Specified by:
- putFirst in interface BlockingDeque<E>
- Throws:
NullPointerException
-InterruptedException
-
public void putLast(E e) throws InterruptedException
- Specified by:
- putLast in interface BlockingDeque<E>
- Throws:
NullPointerException
-InterruptedException
-
public int remainingCapacity()
Returns the number of additional elements that this deque can ideally (in the absence of memory or resource constraints) accept without blocking. This is always equal to the initial capacity of this deque less the current size of this deque. Note that you cannot always tell if an attempt to insert an element will succeed by inspecting remainingCapacity because it may be the case that another thread is about to insert or remove an element.
- Specified by:
- remainingCapacity in interface BlockingQueue<E>
public E remove()
Retrieves and removes the head of the queue represented by this deque. This method differs frompoll
only in that it throws an exception if this deque is empty. This method is equivalent toremoveFirst
.
- Specified by:
- remove in interface BlockingDeque<E>
- remove in interface Queue<E>
- remove in interface Deque<E>
- Overrides:
- remove in interface AbstractQueue<E>
- Returns:
- the head of the queue represented by this deque
- Throws:
NoSuchElementException
- if this deque is empty
public boolean remove(Object o)
Removes the first occurrence of the specified element from this deque. If the deque does not contain the element, it is unchanged. More formally, removes the first element e such that o.equals(e) (if such an element exists). Returns true if this deque contained the specified element (or equivalently, if this deque changed as a result of the call). This method is equivalent toremoveFirstOccurrence
.
- Specified by:
- remove in interface BlockingDeque<E>
- remove in interface BlockingQueue<E>
- remove in interface Collection<E>
- remove in interface Deque<E>
- Overrides:
- remove in interface AbstractCollection<E>
- Parameters:
o
- element to be removed from this deque, if present
- Returns:
- true if this deque changed as a result of the call
public E removeFirst()
- Specified by:
- removeFirst in interface Deque<E>
- Throws:
NoSuchElementException
-
public boolean removeFirstOccurrence(Object o)
Removes the first occurrence of the specified element from this deque. If the deque does not contain the element, it is unchanged. More formally, removes the first element e such that (o==null ? e==null : o.equals(e)) (if such an element exists). Returns true if this deque contained the specified element (or equivalently, if this deque changed as a result of the call).
- Specified by:
- removeFirstOccurrence in interface BlockingDeque<E>
- removeFirstOccurrence in interface Deque<E>
- Parameters:
o
- element to be removed from this deque, if present
- Returns:
- true if an element was removed as a result of this call
- Throws:
ClassCastException
- if the class of the specified element is incompatible with this deque (optional)NullPointerException
- if the specified element is null and this deque does not permit null elements (optional)
public E removeLast()
- Specified by:
- removeLast in interface Deque<E>
- Throws:
NoSuchElementException
-
public boolean removeLastOccurrence(Object o)
Removes the last occurrence of the specified element from this deque. If the deque does not contain the element, it is unchanged. More formally, removes the last element e such that (o==null ? e==null : o.equals(e)) (if such an element exists). Returns true if this deque contained the specified element (or equivalently, if this deque changed as a result of the call).
- Specified by:
- removeLastOccurrence in interface BlockingDeque<E>
- removeLastOccurrence in interface Deque<E>
- Parameters:
o
- element to be removed from this deque, if present
- Returns:
- true if an element was removed as a result of this call
- Throws:
ClassCastException
- if the class of the specified element is incompatible with this deque (optional)NullPointerException
- if the specified element is null and this deque does not permit null elements (optional)
public int size()
Returns the number of elements in this deque.
- Specified by:
- size in interface BlockingDeque<E>
- size in interface Collection<E>
- size in interface Deque<E>
- Overrides:
- size in interface AbstractCollection<E>
- Returns:
- the number of elements in this deque
public E take() throws InterruptedException
- Specified by:
- take in interface BlockingDeque<E>
- take in interface BlockingQueue<E>
public E takeFirst() throws InterruptedException
- Specified by:
- takeFirst in interface BlockingDeque<E>
public E takeLast() throws InterruptedException
- Specified by:
- takeLast in interface BlockingDeque<E>
public Object[] toArray()
Returns an array containing all of the elements in this deque, in proper sequence (from first to last element). 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.
- Specified by:
- toArray in interface Collection<E>
- Overrides:
- toArray in interface AbstractCollection<E>
- Returns:
- an array containing all of the elements in this deque
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