- java.lang.Object
- 
- java.util.AbstractCollection<E>
- 
- java.util.AbstractQueue<E>
- 
- java.util.concurrent.LinkedBlockingDeque<E>
 
 
 
- 
- 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>
 
 public class LinkedBlockingDeque<E> extends AbstractQueue<E> implements BlockingDeque<E>, Serializable An optionally-bounded blocking deque based on linked nodes.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 CollectionandIteratorinterfaces.This class is a member of the Java Collections Framework. - Since:
- 1.6
- See Also:
- Serialized Form
 
- 
- 
Constructor SummaryConstructors Constructor Description LinkedBlockingDeque()Creates 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 SummaryAll Methods Instance Methods Concrete Methods Modifier and Type Method Description booleanadd(E e)Inserts 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.voidaddFirst(E e)Inserts 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.voidaddLast(E e)Inserts 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.booleancontains(Object o)Returnstrueif this deque contains the specified element.Iterator<E>descendingIterator()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.Eelement()Retrieves, but does not remove, the head of the queue represented by this deque.voidforEach(Consumer<? super E> action)Performs the given action for each element of theIterableuntil all elements have been processed or the action throws an exception.EgetFirst()Retrieves, but does not remove, the first element of this deque.EgetLast()Retrieves, but does not remove, the last element of this deque.Iterator<E>iterator()Returns an iterator over the elements in this deque in proper sequence.booleanoffer(E e)Inserts 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.booleanoffer(E e, long timeout, TimeUnit unit)Inserts 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.booleanofferLast(E e)Inserts 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.booleanofferLast(E e, long timeout, TimeUnit unit)Inserts the specified element at the end of this deque, waiting up to the specified wait time if necessary for space to become available.Epop()Pops an element from the stack represented by this deque.voidpush(E e)Pushes 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.voidput(E e)Inserts 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.voidputFirst(E e)Inserts the specified element at the front of this deque, waiting if necessary for space to become available.voidputLast(E e)Inserts the specified element at the end of this deque, waiting if necessary for space to become available.intremainingCapacity()Returns the number of additional elements that this deque can ideally (in the absence of memory or resource constraints) accept without blocking.Eremove()Retrieves and removes the head of the queue represented by this deque.booleanremove(Object o)Removes 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).EremoveFirst()Retrieves and removes the first element of this deque.booleanremoveIf(Predicate<? super E> filter)Removes all of the elements of this collection that satisfy the given predicate.EremoveLast()Retrieves and removes the last element of 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.Spliterator<E>spliterator()Returns aSpliteratorover the elements in this deque.Object[]toArray()Returns an array containing all of the elements in this deque, in proper sequence (from first to last element).<T> T[]toArray(T[] a)Returns an array containing all of the elements in this deque, in proper sequence; the runtime type of the returned array is that of the specified array.- 
Methods declared in class java.util.AbstractCollectioncontainsAll, isEmpty, toString
 - 
Methods declared in class java.lang.Objectclone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 - 
Methods declared in interface java.util.concurrent.BlockingDequepeek, poll, poll, pollFirst, pollLast, removeFirstOccurrence, removeLastOccurrence, take, takeFirst, takeLast
 - 
Methods declared in interface java.util.CollectioncontainsAll, equals, hashCode, isEmpty, parallelStream, stream, toArray
 
- 
 
- 
- 
- 
Constructor Detail- 
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
 
 - 
LinkedBlockingDequepublic 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.- Parameters:
- c- the collection of elements to initially contain
- Throws:
- NullPointerException- if the specified collection or any of its elements are null
 
 
- 
 - 
Method Detail- 
addFirstpublic void addFirst(E e) 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 interface- BlockingDeque<E>
- Specified by:
- addFirstin interface- Deque<E>
- Parameters:
- e- the element to add
- Throws:
- IllegalStateException- if this deque is full
- NullPointerException- if the specified element is null
 
 - 
addLastpublic void addLast(E e) 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 interface- BlockingDeque<E>
- Specified by:
- addLastin interface- Deque<E>
- Parameters:
- e- the element to add
- Throws:
- IllegalStateException- if this deque is full
- NullPointerException- if the specified element is null
 
 - 
offerFirstpublic boolean offerFirst(E e) 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 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
 
 - 
offerLastpublic boolean offerLast(E e) 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 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
 
 - 
putFirstpublic void putFirst(E e) throws InterruptedException 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 interface- BlockingDeque<E>
- Parameters:
- e- the element to add
- Throws:
- NullPointerException- if the specified element is null
- InterruptedException- if interrupted while waiting
 
 - 
putLastpublic void putLast(E e) throws InterruptedException 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 interface- BlockingDeque<E>
- Parameters:
- e- the element to add
- Throws:
- NullPointerException- if the specified element is null
- InterruptedException- if interrupted while waiting
 
 - 
offerFirstpublic boolean offerFirst(E e, long timeout, TimeUnit unit) throws InterruptedException 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 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
 
 - 
offerLastpublic boolean offerLast(E e, long timeout, TimeUnit unit) throws InterruptedException 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 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
 
 - 
removeFirstpublic E 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 interface- Deque<E>
- Returns:
- the head of this deque
- Throws:
- NoSuchElementException- if this deque is empty
 
 - 
removeLastpublic E 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 interface- Deque<E>
- Returns:
- the tail of this deque
- Throws:
- NoSuchElementException- if this deque is empty
 
 - 
getFirstpublic E 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 interface- Deque<E>
- Returns:
- the head of this deque
- Throws:
- NoSuchElementException- if this deque is empty
 
 - 
getLastpublic E 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 interface- Deque<E>
- Returns:
- the tail of this deque
- Throws:
- NoSuchElementException- if this deque is empty
 
 - 
addpublic 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 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
 
 - 
offerpublic boolean offer(E e) 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 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
 
 - 
putpublic void put(E e) throws InterruptedException 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 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
 
 - 
offerpublic boolean offer(E e, long timeout, TimeUnit unit) throws InterruptedException 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 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
 
 - 
removepublic 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 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
 
 - 
elementpublic 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 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
 
 - 
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
 
 - 
drainTopublic int drainTo(Collection<? super E> c) 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 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
 
 - 
drainTopublic int drainTo(Collection<? super E> c, int maxElements) 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 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
 
 - 
pushpublic void push(E e) 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 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
 
 - 
poppublic E 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 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
 
 - 
removepublic 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 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
 
 - 
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
 
 - 
containspublic boolean contains(Object o) 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 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
 
 - 
addAllpublic boolean addAll(Collection<? extends E> c) Appends all of the elements in the specified collection to the end of this deque, in the order that they are returned by the specified collection's iterator. 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:
- add(Object)
 
 - 
toArraypublic 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:
- toArrayin interface- Collection<E>
- Overrides:
- toArrayin class- AbstractCollection<E>
- Returns:
- an array containing all of the elements in this deque
 
 - 
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
 
 - 
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>
 
 - 
iteratorpublic Iterator<E> 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 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
 
 - 
descendingIteratorpublic Iterator<E> 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 interface- Deque<E>
- Returns:
- an iterator over the elements in this deque in reverse order
 
 - 
spliteratorpublic Spliterator<E> spliterator() Returns 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
 
 - 
forEachpublic void forEach(Consumer<? super E> action) 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 interface- Iterable<E>
- Parameters:
- action- The action to be performed for each element
- Throws:
- NullPointerException- if the specified action is null
 
 - 
removeIfpublic boolean removeIf(Predicate<? super E> filter) 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 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
 
 - 
removeAllpublic boolean removeAll(Collection<?> c) 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 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:
- AbstractCollection.remove(Object),- AbstractCollection.contains(Object)
 
 - 
retainAllpublic boolean retainAll(Collection<?> c) 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 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:
- AbstractCollection.remove(Object),- AbstractCollection.contains(Object)
 
 
- 
 
-