- 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>
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:
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Constructor Summary
ConstructorsConstructorDescriptionCreates 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. -
Method Summary
Modifier 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.AbstractCollection
containsAll, isEmpty, toStringMethods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitMethods declared in interface java.util.Collection
containsAll, equals, hashCode, isEmpty, parallelStream, stream, toArray
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Constructor Details
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LinkedBlockingDeque
public LinkedBlockingDeque()Creates aLinkedBlockingDequewith a capacity ofInteger.MAX_VALUE. -
LinkedBlockingDeque
public LinkedBlockingDeque(int capacity) Creates aLinkedBlockingDequewith the given (fixed) capacity.- Parameters:
capacity- the capacity of this deque- Throws:
IllegalArgumentException- ifcapacityis less than 1
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LinkedBlockingDeque
Creates 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
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Method Details
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addFirst
Description 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 interfaceBlockingDeque<E>- Specified by:
addFirstin interfaceDeque<E>- Parameters:
e- the element to add- Throws:
IllegalStateException- if this deque is fullNullPointerException- if the specified element is null
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addLast
Description 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 interfaceBlockingDeque<E>- Specified by:
addLastin interfaceDeque<E>- Parameters:
e- the element to add- Throws:
IllegalStateException- if this deque is fullNullPointerException- if the specified element is null
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offerFirst
Description 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 interfaceBlockingDeque<E>- Specified by:
offerFirstin interfaceDeque<E>- Parameters:
e- the element to add- Returns:
trueif the element was added to this deque, elsefalse- Throws:
NullPointerException- if the specified element is null
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offerLast
Description 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 interfaceBlockingDeque<E>- Specified by:
offerLastin interfaceDeque<E>- Parameters:
e- the element to add- Returns:
trueif the element was added to this deque, elsefalse- Throws:
NullPointerException- if the specified element is null
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putFirst
Description copied from interface:BlockingDequeInserts the specified element at the front of this deque, waiting if necessary for space to become available.- Specified by:
putFirstin interfaceBlockingDeque<E>- Parameters:
e- the element to add- Throws:
NullPointerException- if the specified element is nullInterruptedException- if interrupted while waiting
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putLast
Description copied from interface:BlockingDequeInserts the specified element at the end of this deque, waiting if necessary for space to become available.- Specified by:
putLastin interfaceBlockingDeque<E>- Parameters:
e- the element to add- Throws:
NullPointerException- if the specified element is nullInterruptedException- if interrupted while waiting
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offerFirst
Description 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 interfaceBlockingDeque<E>- Parameters:
e- the element to addtimeout- how long to wait before giving up, in units ofunitunit- aTimeUnitdetermining how to interpret thetimeoutparameter- Returns:
trueif successful, orfalseif the specified waiting time elapses before space is available- Throws:
NullPointerException- if the specified element is nullInterruptedException- if interrupted while waiting
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offerLast
Description 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 interfaceBlockingDeque<E>- Parameters:
e- the element to addtimeout- how long to wait before giving up, in units ofunitunit- aTimeUnitdetermining how to interpret thetimeoutparameter- Returns:
trueif successful, orfalseif the specified waiting time elapses before space is available- Throws:
NullPointerException- if the specified element is nullInterruptedException- if interrupted while waiting
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removeFirst
Description 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 interfaceDeque<E>- Returns:
- the head of this deque
- Throws:
NoSuchElementException- if this deque is empty
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removeLast
Description 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 interfaceDeque<E>- Returns:
- the tail of this deque
- Throws:
NoSuchElementException- if this deque is empty
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pollFirst
Description copied from interface:DequeRetrieves and removes the first element of this deque, or returnsnullif this deque is empty. -
pollLast
Description copied from interface:DequeRetrieves and removes the last element of this deque, or returnsnullif this deque is empty. -
takeFirst
Description copied from interface:BlockingDequeRetrieves and removes the first element of this deque, waiting if necessary until an element becomes available.- Specified by:
takeFirstin interfaceBlockingDeque<E>- Returns:
- the head of this deque
- Throws:
InterruptedException- if interrupted while waiting
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takeLast
Description copied from interface:BlockingDequeRetrieves and removes the last element of this deque, waiting if necessary until an element becomes available.- Specified by:
takeLastin interfaceBlockingDeque<E>- Returns:
- the tail of this deque
- Throws:
InterruptedException- if interrupted while waiting
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pollFirst
Description 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 interfaceBlockingDeque<E>- Parameters:
timeout- how long to wait before giving up, in units ofunitunit- aTimeUnitdetermining how to interpret thetimeoutparameter- 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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pollLast
Description 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 interfaceBlockingDeque<E>- Parameters:
timeout- how long to wait before giving up, in units ofunitunit- aTimeUnitdetermining how to interpret thetimeoutparameter- 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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getFirst
Description 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 interfaceDeque<E>- Returns:
- the head of this deque
- Throws:
NoSuchElementException- if this deque is empty
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getLast
Description 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 interfaceDeque<E>- Returns:
- the tail of this deque
- Throws:
NoSuchElementException- if this deque is empty
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peekFirst
Description copied from interface:DequeRetrieves, but does not remove, the first element of this deque, or returnsnullif this deque is empty. -
peekLast
Description copied from interface:DequeRetrieves, but does not remove, the last element of this deque, or returnsnullif this deque is empty. -
removeFirstOccurrence
Description 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 interfaceBlockingDeque<E>- Specified by:
removeFirstOccurrencein interfaceDeque<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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removeLastOccurrence
Description 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 interfaceBlockingDeque<E>- Specified by:
removeLastOccurrencein interfaceDeque<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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add
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 to
addLast(E).- Specified by:
addin interfaceBlockingDeque<E>- Specified by:
addin interfaceBlockingQueue<E>- Specified by:
addin interfaceCollection<E>- Specified by:
addin interfaceDeque<E>- Specified by:
addin interfaceQueue<E>- Overrides:
addin classAbstractQueue<E>- Parameters:
e- the element to add- Returns:
true(as specified byCollection.add(E))- Throws:
IllegalStateException- if this deque is fullNullPointerException- if the specified element is null
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offer
Description 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 interfaceBlockingDeque<E>- Specified by:
offerin interfaceBlockingQueue<E>- Specified by:
offerin interfaceDeque<E>- Specified by:
offerin interfaceQueue<E>- Parameters:
e- the element to add- Returns:
trueif the element was added to this queue, elsefalse- Throws:
NullPointerException- if the specified element is null
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put
Description 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 interfaceBlockingDeque<E>- Specified by:
putin interfaceBlockingQueue<E>- Parameters:
e- the element to add- Throws:
NullPointerException- if the specified element is nullInterruptedException- if interrupted while waiting
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offer
Description 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 interfaceBlockingDeque<E>- Specified by:
offerin interfaceBlockingQueue<E>- Parameters:
e- the element to addtimeout- how long to wait before giving up, in units ofunitunit- aTimeUnitdetermining how to interpret thetimeoutparameter- Returns:
trueif the element was added to this deque, elsefalse- Throws:
NullPointerException- if the specified element is nullInterruptedException- if interrupted while waiting
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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 to
removeFirst.- Specified by:
removein interfaceBlockingDeque<E>- Specified by:
removein interfaceDeque<E>- Specified by:
removein interfaceQueue<E>- Overrides:
removein classAbstractQueue<E>- Returns:
- the head of the queue represented by this deque
- Throws:
NoSuchElementException- if this deque is empty
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poll
Description 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(). -
take
Description 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 interfaceBlockingDeque<E>- Specified by:
takein interfaceBlockingQueue<E>- Returns:
- the head of this deque
- Throws:
InterruptedException- if interrupted while waiting
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poll
Description 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 interfaceBlockingDeque<E>- Specified by:
pollin interfaceBlockingQueue<E>- Parameters:
timeout- how long to wait before giving up, in units ofunitunit- aTimeUnitdetermining how to interpret thetimeoutparameter- 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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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 to
getFirst.- Specified by:
elementin interfaceBlockingDeque<E>- Specified by:
elementin interfaceDeque<E>- Specified by:
elementin interfaceQueue<E>- Overrides:
elementin classAbstractQueue<E>- Returns:
- the head of the queue represented by this deque
- Throws:
NoSuchElementException- if this deque is empty
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peek
Description 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. -
remainingCapacity
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 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 interfaceBlockingQueue<E>- Returns:
- the remaining capacity
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drainTo
Description 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 interfaceBlockingQueue<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 collectionClassCastException- if the class of an element of this queue prevents it from being added to the specified collectionNullPointerException- if the specified collection is nullIllegalArgumentException- 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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drainTo
Description 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 interfaceBlockingQueue<E>- Parameters:
c- the collection to transfer elements intomaxElements- 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 collectionClassCastException- if the class of an element of this queue prevents it from being added to the specified collectionNullPointerException- if the specified collection is nullIllegalArgumentException- 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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push
Description 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 interfaceBlockingDeque<E>- Specified by:
pushin interfaceDeque<E>- Parameters:
e- the element to push- Throws:
IllegalStateException- if this deque is fullNullPointerException- if the specified element is null
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pop
Description 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 interfaceDeque<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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remove
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 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 interfaceBlockingDeque<E>- Specified by:
removein interfaceBlockingQueue<E>- Specified by:
removein interfaceCollection<E>- Specified by:
removein interfaceDeque<E>- Overrides:
removein classAbstractCollection<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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size
public int size()Returns the number of elements in this deque.- Specified by:
sizein interfaceBlockingDeque<E>- Specified by:
sizein interfaceCollection<E>- Specified by:
sizein interfaceDeque<E>- Returns:
- the number of elements in this deque
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contains
Returnstrueif 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 interfaceBlockingDeque<E>- Specified by:
containsin interfaceBlockingQueue<E>- Specified by:
containsin interfaceCollection<E>- Specified by:
containsin interfaceDeque<E>- Overrides:
containsin classAbstractCollection<E>- Parameters:
o- object to be checked for containment in this deque- Returns:
trueif this deque contains the specified element
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addAll
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. Attempts toaddAllof a deque to itself result inIllegalArgumentException.- Specified by:
addAllin interfaceCollection<E>- Specified by:
addAllin interfaceDeque<E>- Overrides:
addAllin classAbstractQueue<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 nullIllegalArgumentException- if the collection is this dequeIllegalStateException- if this deque is full- See Also:
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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:
toArrayin interfaceCollection<E>- Overrides:
toArrayin classAbstractCollection<E>- Returns:
- an array containing all of the elements in this deque
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toArray
public <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 interfaceCollection<E>- Overrides:
toArrayin classAbstractCollection<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 dequeNullPointerException- if the specified array is null
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clear
public void clear()Atomically removes all of the elements from this deque. The deque will be empty after this call returns.- Specified by:
clearin interfaceCollection<E>- Overrides:
clearin classAbstractQueue<E>
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iterator
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 weakly consistent.
- Specified by:
iteratorin interfaceBlockingDeque<E>- Specified by:
iteratorin interfaceCollection<E>- Specified by:
iteratorin interfaceDeque<E>- Specified by:
iteratorin interfaceIterable<E>- Specified by:
iteratorin classAbstractCollection<E>- Returns:
- an iterator over the elements in this deque in proper sequence
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descendingIterator
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 weakly consistent.
- Specified by:
descendingIteratorin interfaceDeque<E>- Returns:
- an iterator over the elements in this deque in reverse order
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spliterator
Returns aSpliteratorover the elements in this deque.The returned spliterator is weakly consistent.
The
SpliteratorreportsSpliterator.CONCURRENT,Spliterator.ORDERED, andSpliterator.NONNULL.- Specified by:
spliteratorin interfaceCollection<E>- Specified by:
spliteratorin interfaceIterable<E>- Implementation Note:
- The
SpliteratorimplementstrySplitto permit limited parallelism. - Returns:
- a
Spliteratorover the elements in this deque - Since:
- 1.8
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forEach
Description 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 interfaceIterable<E>- Parameters:
action- The action to be performed for each element- Throws:
NullPointerException- if the specified action is null
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removeIf
Description 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 interfaceCollection<E>- Parameters:
filter- a predicate which returnstruefor elements to be removed- Returns:
trueif any elements were removed- Throws:
NullPointerException- if the specified filter is null
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removeAll
Description 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 interfaceCollection<E>- Overrides:
removeAllin classAbstractCollection<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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retainAll
Description 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 interfaceCollection<E>- Overrides:
retainAllin classAbstractCollection<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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