- Type Parameters:
- E- the type of elements held in this deque
- All Implemented Interfaces:
- Serializable,- Iterable<E>,- Collection<E>,- BlockingDeque<E>,- BlockingQueue<E>,- Deque<E>,- Queue<E>,- SequencedCollection<E>
The optional capacity bound constructor argument serves as a
 way to prevent excessive expansion. The capacity, if unspecified,
 is equal to 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 Java Collections Framework.
- Since:
- 1.6
- See Also:
- 
Constructor SummaryConstructorsConstructorDescriptionCreates aLinkedBlockingDequewith a capacity ofInteger.MAX_VALUE.LinkedBlockingDeque(int capacity) Creates aLinkedBlockingDequewith the given (fixed) capacity.LinkedBlockingDeque(Collection<? extends E> c) Creates aLinkedBlockingDequewith a capacity ofInteger.MAX_VALUE, initially containing the elements of the given collection, added in traversal order of the collection's iterator.
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Method SummaryModifier and TypeMethodDescriptionbooleanInserts the specified element at the end of this deque unless it would violate capacity restrictions.booleanaddAll(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.voidInserts the specified element at the front of this deque if it is possible to do so immediately without violating capacity restrictions, throwing anIllegalStateExceptionif no space is currently available.voidInserts the specified element at the end of this deque if it is possible to do so immediately without violating capacity restrictions, throwing anIllegalStateExceptionif no space is currently available.voidclear()Atomically removes all of the elements from this deque.booleanReturnstrueif this deque contains the specified element.Returns an iterator over the elements in this deque in reverse sequential order.intdrainTo(Collection<? super E> c) Removes all available elements from this queue and adds them to the given collection.intdrainTo(Collection<? super E> c, int maxElements) Removes at most the given number of available elements from this queue and adds them to the given collection.element()Retrieves, but does not remove, the head of the queue represented by this deque.voidPerforms the given action for each element of theIterableuntil all elements have been processed or the action throws an exception.getFirst()Retrieves, but does not remove, the first element of this deque.getLast()Retrieves, but does not remove, the last element of this deque.iterator()Returns an iterator over the elements in this deque in proper sequence.booleanInserts the specified element into the queue represented by this deque (in other words, at the tail of this deque) if it is possible to do so immediately without violating capacity restrictions, returningtrueupon success andfalseif no space is currently available.booleanInserts the specified element into the queue represented by this deque (in other words, at the tail of this deque), waiting up to the specified wait time if necessary for space to become available.booleanofferFirst(E e) Inserts the specified element at the front of this deque if it is possible to do so immediately without violating capacity restrictions, returningtrueupon success andfalseif no space is currently available.booleanofferFirst(E e, long timeout, TimeUnit unit) Inserts the specified element at the front of this deque, waiting up to the specified wait time if necessary for space to become available.booleanInserts the specified element at the end of this deque if it is possible to do so immediately without violating capacity restrictions, returningtrueupon success andfalseif no space is currently available.booleanInserts the specified element at the end of this deque, waiting up to the specified wait time if necessary for space to become available.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 returnsnullif this deque is empty.Retrieves, but does not remove, the first element of this deque, or returnsnullif this deque is empty.peekLast()Retrieves, but does not remove, the last element of this deque, or returnsnullif this deque is empty.poll()Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), or returnsnullif this deque is empty.Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), waiting up to the specified wait time if necessary for an element to become available.Retrieves and removes the first element of this deque, or returnsnullif this deque is empty.Retrieves and removes the first element of this deque, waiting up to the specified wait time if necessary for an element to become available.pollLast()Retrieves and removes the last element of this deque, or returnsnullif this deque is empty.Retrieves and removes the last element of this deque, waiting up to the specified wait time if necessary for an element to become available.pop()Pops an element from the stack represented by this deque.voidPushes an element onto the stack represented by this deque (in other words, at the head of this deque) if it is possible to do so immediately without violating capacity restrictions, throwing anIllegalStateExceptionif no space is currently available.voidInserts the specified element into the queue represented by this deque (in other words, at the tail of this deque), waiting if necessary for space to become available.voidInserts the specified element at the front of this deque, waiting if necessary for space to become available.voidInserts the specified element at the end of this deque, waiting if necessary for space to become available.intReturns the number of additional elements that this deque can ideally (in the absence of memory or resource constraints) accept without blocking.remove()Retrieves and removes the head of the queue represented by this deque.booleanRemoves the first occurrence of the specified element from this deque.booleanremoveAll(Collection<?> c) Removes all of this collection's elements that are also contained in the specified collection (optional operation).Retrieves and removes the first element of this deque.booleanRemoves the first occurrence of the specified element from this deque.booleanRemoves all of the elements of this collection that satisfy the given predicate.Retrieves and removes the last element of this deque.booleanRemoves the last occurrence of the specified element from this deque.booleanretainAll(Collection<?> c) Retains only the elements in this collection that are contained in the specified collection (optional operation).intsize()Returns the number of elements in this deque.Returns aSpliteratorover the elements in this deque.take()Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), waiting if necessary until an element becomes available.Retrieves and removes the first element of this deque, waiting if necessary until an element becomes available.takeLast()Retrieves and removes the last element of this deque, waiting if necessary until an element becomes available.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; the runtime type of the returned array is that of the specified array.Methods declared in class java.util.AbstractCollectioncontainsAll, isEmpty, toStringMethods declared in class java.lang.Objectclone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitMethods declared in interface java.util.CollectioncontainsAll, equals, hashCode, isEmpty, parallelStream, stream, toArray
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Constructor Details- 
LinkedBlockingDequepublic LinkedBlockingDeque()Creates aLinkedBlockingDequewith a capacity ofInteger.MAX_VALUE.
- 
LinkedBlockingDequepublic LinkedBlockingDeque(int capacity) Creates aLinkedBlockingDequewith the given (fixed) capacity.- Parameters:
- capacity- the capacity of this deque
- Throws:
- IllegalArgumentException- if- capacityis less than 1
 
- 
LinkedBlockingDequeCreates aLinkedBlockingDequewith 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
 
 
- 
- 
Method Details- 
addFirstDescription copied from interface:BlockingDequeInserts the specified element at the front of this deque if it is possible to do so immediately without violating capacity restrictions, throwing anIllegalStateExceptionif no space is currently available. When using a capacity-restricted deque, it is generally preferable to useofferFirst.- Specified by:
- addFirstin interface- BlockingDeque<E>
- Specified by:
- addFirstin interface- Deque<E>
- Specified by:
- addFirstin interface- SequencedCollection<E>
- Parameters:
- e- the element to add
- Throws:
- IllegalStateException- if this deque is full
- NullPointerException- if the specified element is null
 
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addLastDescription copied from interface:BlockingDequeInserts the specified element at the end of this deque if it is possible to do so immediately without violating capacity restrictions, throwing anIllegalStateExceptionif no space is currently available. When using a capacity-restricted deque, it is generally preferable to useofferLast.- Specified by:
- addLastin interface- BlockingDeque<E>
- Specified by:
- addLastin interface- Deque<E>
- Specified by:
- addLastin interface- SequencedCollection<E>
- Parameters:
- e- the element to add
- Throws:
- IllegalStateException- if this deque is full
- NullPointerException- if the specified element is null
 
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offerFirstDescription copied from interface:BlockingDequeInserts the specified element at the front of this deque if it is possible to do so immediately without violating capacity restrictions, returningtrueupon success andfalseif no space is currently available. When using a capacity-restricted deque, this method is generally preferable to theaddFirstmethod, which can fail to insert an element only by throwing an exception.- Specified by:
- offerFirstin interface- BlockingDeque<E>
- Specified by:
- offerFirstin interface- Deque<E>
- Parameters:
- e- the element to add
- Returns:
- trueif the element was added to this deque, else- false
- Throws:
- NullPointerException- if the specified element is null
 
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offerLastDescription copied from interface:BlockingDequeInserts the specified element at the end of this deque if it is possible to do so immediately without violating capacity restrictions, returningtrueupon success andfalseif no space is currently available. When using a capacity-restricted deque, this method is generally preferable to theaddLastmethod, which can fail to insert an element only by throwing an exception.- Specified by:
- offerLastin interface- BlockingDeque<E>
- Specified by:
- offerLastin interface- Deque<E>
- Parameters:
- e- the element to add
- Returns:
- trueif the element was added to this deque, else- false
- Throws:
- NullPointerException- if the specified element is null
 
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putFirstDescription copied from interface:BlockingDequeInserts the specified element at the front of this deque, waiting if necessary for space to become available.- Specified by:
- putFirstin interface- BlockingDeque<E>
- Parameters:
- e- the element to add
- Throws:
- NullPointerException- if the specified element is null
- InterruptedException- if interrupted while waiting
 
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putLastDescription copied from interface:BlockingDequeInserts the specified element at the end of this deque, waiting if necessary for space to become available.- Specified by:
- putLastin interface- BlockingDeque<E>
- Parameters:
- e- the element to add
- Throws:
- NullPointerException- if the specified element is null
- InterruptedException- if interrupted while waiting
 
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offerFirstDescription copied from interface:BlockingDequeInserts the specified element at the front of this deque, waiting up to the specified wait time if necessary for space to become available.- Specified by:
- offerFirstin interface- BlockingDeque<E>
- Parameters:
- e- the element to add
- timeout- how long to wait before giving up, in units of- unit
- unit- a- TimeUnitdetermining how to interpret the- timeoutparameter
- Returns:
- trueif successful, or- falseif the specified waiting time elapses before space is available
- Throws:
- NullPointerException- if the specified element is null
- InterruptedException- if interrupted while waiting
 
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offerLastDescription copied from interface:BlockingDequeInserts the specified element at the end of this deque, waiting up to the specified wait time if necessary for space to become available.- Specified by:
- offerLastin interface- BlockingDeque<E>
- Parameters:
- e- the element to add
- timeout- how long to wait before giving up, in units of- unit
- unit- a- TimeUnitdetermining how to interpret the- timeoutparameter
- Returns:
- trueif successful, or- falseif the specified waiting time elapses before space is available
- Throws:
- NullPointerException- if the specified element is null
- InterruptedException- if interrupted while waiting
 
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removeFirstDescription copied from interface:DequeRetrieves and removes the first element of this deque. This method differs frompollFirstonly in that it throws an exception if this deque is empty.- Specified by:
- removeFirstin interface- Deque<E>
- Specified by:
- removeFirstin interface- SequencedCollection<E>
- Returns:
- the head of this deque
- Throws:
- NoSuchElementException- if this deque is empty
 
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removeLastDescription copied from interface:DequeRetrieves and removes the last element of this deque. This method differs frompollLastonly in that it throws an exception if this deque is empty.- Specified by:
- removeLastin interface- Deque<E>
- Specified by:
- removeLastin interface- SequencedCollection<E>
- Returns:
- the tail of this deque
- Throws:
- NoSuchElementException- if this deque is empty
 
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pollFirstDescription copied from interface:DequeRetrieves and removes the first element of this deque, or returnsnullif this deque is empty.
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pollLastDescription copied from interface:DequeRetrieves and removes the last element of this deque, or returnsnullif this deque is empty.
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takeFirstDescription copied from interface:BlockingDequeRetrieves and removes the first element of this deque, waiting if necessary until an element becomes available.- Specified by:
- takeFirstin interface- BlockingDeque<E>
- Returns:
- the head of this deque
- Throws:
- InterruptedException- if interrupted while waiting
 
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takeLastDescription copied from interface:BlockingDequeRetrieves and removes the last element of this deque, waiting if necessary until an element becomes available.- Specified by:
- takeLastin interface- BlockingDeque<E>
- Returns:
- the tail of this deque
- Throws:
- InterruptedException- if interrupted while waiting
 
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pollFirstDescription copied from interface:BlockingDequeRetrieves and removes the first element of this deque, waiting up to the specified wait time if necessary for an element to become available.- Specified by:
- pollFirstin interface- BlockingDeque<E>
- Parameters:
- timeout- how long to wait before giving up, in units of- unit
- unit- a- TimeUnitdetermining how to interpret the- timeoutparameter
- Returns:
- the head of this deque, or nullif the specified waiting time elapses before an element is available
- Throws:
- InterruptedException- if interrupted while waiting
 
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pollLastDescription copied from interface:BlockingDequeRetrieves and removes the last element of this deque, waiting up to the specified wait time if necessary for an element to become available.- Specified by:
- pollLastin interface- BlockingDeque<E>
- Parameters:
- timeout- how long to wait before giving up, in units of- unit
- unit- a- TimeUnitdetermining how to interpret the- timeoutparameter
- Returns:
- the tail of this deque, or nullif the specified waiting time elapses before an element is available
- Throws:
- InterruptedException- if interrupted while waiting
 
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getFirstDescription copied from interface:DequeRetrieves, but does not remove, the first element of this deque. This method differs frompeekFirstonly in that it throws an exception if this deque is empty.- Specified by:
- getFirstin interface- Deque<E>
- Specified by:
- getFirstin interface- SequencedCollection<E>
- Returns:
- the head of this deque
- Throws:
- NoSuchElementException- if this deque is empty
 
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getLastDescription copied from interface:DequeRetrieves, but does not remove, the last element of this deque. This method differs frompeekLastonly in that it throws an exception if this deque is empty.- Specified by:
- getLastin interface- Deque<E>
- Specified by:
- getLastin interface- SequencedCollection<E>
- Returns:
- the tail of this deque
- Throws:
- NoSuchElementException- if this deque is empty
 
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peekFirstDescription copied from interface:DequeRetrieves, but does not remove, the first element of this deque, or returnsnullif this deque is empty.
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peekLastDescription copied from interface:DequeRetrieves, but does not remove, the last element of this deque, or returnsnullif this deque is empty.
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removeFirstOccurrenceDescription copied from interface:BlockingDequeRemoves 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 elementesuch thato.equals(e)(if such an element exists). Returnstrueif this deque contained the specified element (or equivalently, if this deque changed as a result of the call).- Specified by:
- removeFirstOccurrencein interface- BlockingDeque<E>
- Specified by:
- removeFirstOccurrencein interface- Deque<E>
- Parameters:
- o- element to be removed from this deque, if present
- Returns:
- trueif an element was removed as a result of this call
 
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removeLastOccurrenceDescription copied from interface:BlockingDequeRemoves 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 elementesuch thato.equals(e)(if such an element exists). Returnstrueif this deque contained the specified element (or equivalently, if this deque changed as a result of the call).- Specified by:
- removeLastOccurrencein interface- BlockingDeque<E>
- Specified by:
- removeLastOccurrencein interface- Deque<E>
- Parameters:
- o- element to be removed from this deque, if present
- Returns:
- trueif an element was removed as a result of this call
 
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addInserts 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 to addLast(E).- Specified by:
- addin interface- BlockingDeque<E>
- Specified by:
- addin interface- BlockingQueue<E>
- Specified by:
- addin interface- Collection<E>
- Specified by:
- addin interface- Deque<E>
- Specified by:
- addin interface- Queue<E>
- Overrides:
- addin class- AbstractQueue<E>
- Parameters:
- e- the element to add
- Returns:
- true(as specified by- Collection.add(E))
- Throws:
- IllegalStateException- if this deque is full
- NullPointerException- if the specified element is null
 
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offerDescription copied from interface:BlockingDequeInserts the specified element into the queue represented by this deque (in other words, at the tail of this deque) if it is possible to do so immediately without violating capacity restrictions, returningtrueupon success andfalseif no space is currently available. When using a capacity-restricted deque, this method is generally preferable to theBlockingDeque.add(E)method, which can fail to insert an element only by throwing an exception.This method is equivalent to offerLast.- Specified by:
- offerin interface- BlockingDeque<E>
- Specified by:
- offerin interface- BlockingQueue<E>
- Specified by:
- offerin interface- Deque<E>
- Specified by:
- offerin interface- Queue<E>
- Parameters:
- e- the element to add
- Returns:
- trueif the element was added to this queue, else- false
- Throws:
- NullPointerException- if the specified element is null
 
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putDescription copied from interface:BlockingDequeInserts the specified element into the queue represented by this deque (in other words, at the tail of this deque), waiting if necessary for space to become available.This method is equivalent to putLast.- Specified by:
- putin interface- BlockingDeque<E>
- Specified by:
- putin interface- BlockingQueue<E>
- Parameters:
- e- the element to add
- Throws:
- NullPointerException- if the specified element is null
- InterruptedException- if interrupted while waiting
 
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offerDescription copied from interface:BlockingDequeInserts the specified element into the queue represented by this deque (in other words, at the tail of this deque), waiting up to the specified wait time if necessary for space to become available.This method is equivalent to offerLast.- Specified by:
- offerin interface- BlockingDeque<E>
- Specified by:
- offerin interface- BlockingQueue<E>
- Parameters:
- e- the element to add
- timeout- how long to wait before giving up, in units of- unit
- unit- a- TimeUnitdetermining how to interpret the- timeoutparameter
- Returns:
- trueif the element was added to this deque, else- false
- Throws:
- NullPointerException- if the specified element is null
- InterruptedException- if interrupted while waiting
 
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removeRetrieves 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 to removeFirst.- Specified by:
- removein interface- BlockingDeque<E>
- Specified by:
- removein interface- Deque<E>
- Specified by:
- removein interface- Queue<E>
- Overrides:
- removein class- AbstractQueue<E>
- Returns:
- the head of the queue represented by this deque
- Throws:
- NoSuchElementException- if this deque is empty
 
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pollDescription copied from interface:BlockingDequeRetrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), or returnsnullif this deque is empty.This method is equivalent to Deque.pollFirst().
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takeDescription copied from interface:BlockingDequeRetrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), waiting if necessary until an element becomes available.This method is equivalent to takeFirst.- Specified by:
- takein interface- BlockingDeque<E>
- Specified by:
- takein interface- BlockingQueue<E>
- Returns:
- the head of this deque
- Throws:
- InterruptedException- if interrupted while waiting
 
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pollDescription copied from interface:BlockingDequeRetrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), waiting up to the specified wait time if necessary for an element to become available.This method is equivalent to pollFirst.- Specified by:
- pollin interface- BlockingDeque<E>
- Specified by:
- pollin interface- BlockingQueue<E>
- Parameters:
- timeout- how long to wait before giving up, in units of- unit
- unit- a- TimeUnitdetermining how to interpret the- timeoutparameter
- Returns:
- the head of this deque, or nullif the specified waiting time elapses before an element is available
- Throws:
- InterruptedException- if interrupted while waiting
 
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elementRetrieves, 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 to getFirst.- Specified by:
- elementin interface- BlockingDeque<E>
- Specified by:
- elementin interface- Deque<E>
- Specified by:
- elementin interface- Queue<E>
- Overrides:
- elementin class- AbstractQueue<E>
- Returns:
- the head of the queue represented by this deque
- Throws:
- NoSuchElementException- if this deque is empty
 
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peekDescription copied from interface:BlockingDequeRetrieves, but does not remove, the head of the queue represented by this deque (in other words, the first element of this deque), or returnsnullif this deque is empty.This method is equivalent to peekFirst.
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remainingCapacitypublic 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 currentsizeof this deque.Note that you cannot always tell if an attempt to insert an element will succeed by inspecting remainingCapacitybecause it may be the case that another thread is about to insert or remove an element.- Specified by:
- remainingCapacityin interface- BlockingQueue<E>
- Returns:
- the remaining capacity
 
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drainToDescription copied from interface:BlockingQueueRemoves all available elements from this queue and adds them to the given collection. This operation may be more efficient than repeatedly polling this queue. A failure encountered while attempting to add elements to collectioncmay result in elements being in neither, either or both collections when the associated exception is thrown. Attempts to drain a queue to itself result inIllegalArgumentException. Further, the behavior of this operation is undefined if the specified collection is modified while the operation is in progress.- Specified by:
- drainToin interface- BlockingQueue<E>
- Parameters:
- c- the collection to transfer elements into
- Returns:
- the number of elements transferred
- Throws:
- UnsupportedOperationException- if addition of elements is not supported by the specified collection
- ClassCastException- if the class of an element of this queue prevents it from being added to the specified collection
- NullPointerException- if the specified collection is null
- IllegalArgumentException- if the specified collection is this queue, or some property of an element of this queue prevents it from being added to the specified collection
 
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drainToDescription copied from interface:BlockingQueueRemoves at most the given number of available elements from this queue and adds them to the given collection. A failure encountered while attempting to add elements to collectioncmay result in elements being in neither, either or both collections when the associated exception is thrown. Attempts to drain a queue to itself result inIllegalArgumentException. Further, the behavior of this operation is undefined if the specified collection is modified while the operation is in progress.- Specified by:
- drainToin interface- BlockingQueue<E>
- Parameters:
- c- the collection to transfer elements into
- maxElements- the maximum number of elements to transfer
- Returns:
- the number of elements transferred
- Throws:
- UnsupportedOperationException- if addition of elements is not supported by the specified collection
- ClassCastException- if the class of an element of this queue prevents it from being added to the specified collection
- NullPointerException- if the specified collection is null
- IllegalArgumentException- if the specified collection is this queue, or some property of an element of this queue prevents it from being added to the specified collection
 
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pushDescription copied from interface:BlockingDequePushes an element onto the stack represented by this deque (in other words, at the head of this deque) if it is possible to do so immediately without violating capacity restrictions, throwing anIllegalStateExceptionif no space is currently available.This method is equivalent to addFirst.- Specified by:
- pushin interface- BlockingDeque<E>
- Specified by:
- pushin interface- Deque<E>
- Parameters:
- e- the element to push
- Throws:
- IllegalStateException- if this deque is full
- NullPointerException- if the specified element is null
 
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popDescription copied from interface:DequePops an element from the stack represented by this deque. In other words, removes and returns the first element of this deque.This method is equivalent to Deque.removeFirst().- Specified by:
- popin interface- Deque<E>
- Returns:
- the element at the front of this deque (which is the top of the stack represented by this deque)
- Throws:
- NoSuchElementException- if this deque is empty
 
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removeRemoves 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 elementesuch thato.equals(e)(if such an element exists). Returnstrueif this deque contained the specified element (or equivalently, if this deque changed as a result of the call).This method is equivalent to removeFirstOccurrence.- Specified by:
- removein interface- BlockingDeque<E>
- Specified by:
- removein interface- BlockingQueue<E>
- Specified by:
- removein interface- Collection<E>
- Specified by:
- removein interface- Deque<E>
- Overrides:
- removein class- AbstractCollection<E>
- Parameters:
- o- element to be removed from this deque, if present
- Returns:
- trueif this deque changed as a result of the call
 
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sizepublic int size()Returns the number of elements in this deque.- Specified by:
- sizein interface- BlockingDeque<E>
- Specified by:
- sizein interface- Collection<E>
- Specified by:
- sizein interface- Deque<E>
- Returns:
- the number of elements in this deque
 
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containsReturnstrueif this deque contains the specified element. More formally, returnstrueif and only if this deque contains at least one elementesuch thato.equals(e).- Specified by:
- containsin interface- BlockingDeque<E>
- Specified by:
- containsin interface- BlockingQueue<E>
- Specified by:
- containsin interface- Collection<E>
- Specified by:
- containsin interface- Deque<E>
- Overrides:
- containsin class- AbstractCollection<E>
- Parameters:
- o- object to be checked for containment in this deque
- Returns:
- trueif this deque contains the specified element
 
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addAllAppends 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. Attempts toaddAllof a deque to itself result inIllegalArgumentException.- Specified by:
- addAllin interface- Collection<E>
- Specified by:
- addAllin interface- Deque<E>
- Overrides:
- addAllin class- AbstractQueue<E>
- Parameters:
- c- the elements to be inserted into this deque
- Returns:
- trueif this deque changed as a result of the call
- Throws:
- NullPointerException- if the specified collection or any of its elements are null
- IllegalArgumentException- if the collection is this deque
- IllegalStateException- if this deque is full
- See Also:
 
- 
toArrayReturns 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:
- toArrayin interface- Collection<E>
- Overrides:
- toArrayin class- AbstractCollection<E>
- Returns:
- an array containing all of the elements in this deque
 
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toArraypublic <T> T[] 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 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 xis a deque known to contain only strings. The following code can be used to dump the deque into a newly allocated array ofString:
 Note thatString[] y = x.toArray(new String[0]);toArray(new Object[0])is identical in function totoArray().- Specified by:
- toArrayin interface- Collection<E>
- Overrides:
- toArrayin class- AbstractCollection<E>
- Type Parameters:
- T- the component type of the array to contain the collection
- 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 deque
- NullPointerException- if the specified array is null
 
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clearpublic void clear()Atomically removes all of the elements from this deque. The deque will be empty after this call returns.- Specified by:
- clearin interface- Collection<E>
- Overrides:
- clearin class- AbstractQueue<E>
 
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iteratorReturns 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 weakly consistent. - Specified by:
- iteratorin interface- BlockingDeque<E>
- Specified by:
- iteratorin interface- Collection<E>
- Specified by:
- iteratorin interface- Deque<E>
- Specified by:
- iteratorin interface- Iterable<E>
- Specified by:
- iteratorin class- AbstractCollection<E>
- Returns:
- an iterator over the elements in this deque in proper sequence
 
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descendingIteratorReturns 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 weakly consistent. - Specified by:
- descendingIteratorin interface- Deque<E>
- Returns:
- an iterator over the elements in this deque in reverse order
 
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spliteratorReturns aSpliteratorover the elements in this deque.The returned spliterator is weakly consistent. The SpliteratorreportsSpliterator.CONCURRENT,Spliterator.ORDERED, andSpliterator.NONNULL.- Specified by:
- spliteratorin interface- Collection<E>
- Specified by:
- spliteratorin interface- Iterable<E>
- Implementation Note:
- The SpliteratorimplementstrySplitto permit limited parallelism.
- Returns:
- a Spliteratorover the elements in this deque
- Since:
- 1.8
 
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forEachDescription copied from interface:IterablePerforms the given action for each element of theIterableuntil all elements have been processed or the action throws an exception. Actions are performed in the order of iteration, if that order is specified. Exceptions thrown by the action are relayed to the caller.The behavior of this method is unspecified if the action performs side-effects that modify the underlying source of elements, unless an overriding class has specified a concurrent modification policy. - Specified by:
- forEachin interface- Iterable<E>
- Parameters:
- action- The action to be performed for each element
- Throws:
- NullPointerException- if the specified action is null
 
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removeIfDescription copied from interface:CollectionRemoves all of the elements of this collection that satisfy the given predicate. Errors or runtime exceptions thrown during iteration or by the predicate are relayed to the caller.- Specified by:
- removeIfin interface- Collection<E>
- Parameters:
- filter- a predicate which returns- truefor elements to be removed
- Returns:
- trueif any elements were removed
- Throws:
- NullPointerException- if the specified filter is null
 
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removeAllDescription copied from class:AbstractCollectionRemoves all of this collection's elements that are also contained in the specified collection (optional operation). After this call returns, this collection will contain no elements in common with the specified collection.- Specified by:
- removeAllin interface- Collection<E>
- Overrides:
- removeAllin class- AbstractCollection<E>
- Parameters:
- c- collection containing elements to be removed from this collection
- Returns:
- trueif this collection changed as a result of the call
- Throws:
- NullPointerException- if this collection contains one or more null elements and the specified collection does not support null elements (optional) or if the specified collection is null
- See Also:
 
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retainAllDescription copied from class:AbstractCollectionRetains only the elements in this collection that are contained in the specified collection (optional operation). In other words, removes from this collection all of its elements that are not contained in the specified collection.- Specified by:
- retainAllin interface- Collection<E>
- Overrides:
- retainAllin class- AbstractCollection<E>
- Parameters:
- c- collection containing elements to be retained in this collection
- Returns:
- trueif this collection changed as a result of the call
- Throws:
- NullPointerException- if this collection contains one or more null elements and the specified collection does not permit null elements (optional) or if the specified collection is null
- See Also:
 
 
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