程序包 java.util.concurrent

类 LinkedTransferQueue<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractQueue<E>

java.util.concurrent.LinkedTransferQueue<E>

类型参数:

E - the type of elements held in this collection

所有已实现的接口:

Serializable, Iterable<E>, Collection<E>, BlockingQueue<E>, TransferQueue<E>, Queue<E>

public class LinkedTransferQueue<E>
extends AbstractQueue<E>
implements TransferQueue<E>, Serializable

An unbounded TransferQueue based on linked nodes. This queue orders elements FIFO (first-in-first-out) with respect to any given producer. The head of the queue is that element that has been on the queue the longest time for some producer. The tail of the queue is that element that has been on the queue the shortest time for some producer.

Beware that, unlike in most collections, the size method is NOT a constant-time operation. Because of the asynchronous nature of these queues, determining the current number of elements requires a traversal of the elements, and so may report inaccurate results if this collection is modified during traversal. Additionally, the bulk operations addAll, removeAll, retainAll, containsAll, equals, and toArray are not guaranteed to be performed atomically. For example, an iterator operating concurrently with an addAll operation might view only some of the added elements.

This class and its iterator implement all of the optional methods of the Collection and Iterator interfaces.

Memory consistency effects: As with other concurrent collections, actions in a thread prior to placing an object into a LinkedTransferQueue happen-before actions subsequent to the access or removal of that element from the LinkedTransferQueue in another thread.

This class is a member of the Java Collections Framework.

从以下版本开始:

1.7

另请参阅:

序列化表格

构造器概要

构造器

构造器	说明
LinkedTransferQueue()	Creates an initially empty LinkedTransferQueue.
LinkedTransferQueue(Collection<? extends E> c)	Creates a LinkedTransferQueue initially containing the elements of the given collection, added in traversal order of the collection's iterator.

方法概要

限定符和类型	方法	说明
boolean	add(E e)	Inserts the specified element at the tail of this queue.
boolean	contains(Object o)	Returns true if this queue contains the specified element.
int	drainTo(Collection<? super E> c)	Removes all available elements from this queue and adds them to the given collection.
int	drainTo(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.
int	getWaitingConsumerCount()	Returns an estimate of the number of consumers waiting to receive elements via BlockingQueue.take() or timed poll.
boolean	hasWaitingConsumer()	Returns true if there is at least one consumer waiting to receive an element via BlockingQueue.take() or timed poll.
boolean	isEmpty()	Returns true if this queue contains no elements.
Iterator<E>	iterator()	Returns an iterator over the elements in this queue in proper sequence.
boolean	offer(E e)	Inserts the specified element at the tail of this queue.
boolean	offer(E e, long timeout, TimeUnit unit)	Inserts the specified element at the tail of this queue.
E	peek()	Retrieves, but does not remove, the head of this queue, or returns null if this queue is empty.
E	poll()	Retrieves and removes the head of this queue, or returns null if this queue is empty.
E	poll(long timeout, TimeUnit unit)	Retrieves and removes the head of this queue, waiting up to the specified wait time if necessary for an element to become available.
void	put(E e)	Inserts the specified element at the tail of this queue.
int	remainingCapacity()	Always returns Integer.MAX_VALUE because a LinkedTransferQueue is not capacity constrained.
boolean	remove(Object o)	Removes a single instance of the specified element from this queue, if it is present.
int	size()	Returns the number of elements in this queue.
Spliterator<E>	spliterator()	Returns a Spliterator over the elements in this queue.
E	take()	Retrieves and removes the head of this queue, waiting if necessary until an element becomes available.
void	transfer(E e)	Transfers the element to a consumer, waiting if necessary to do so.
boolean	tryTransfer(E e)	Transfers the element to a waiting consumer immediately, if possible.
boolean	tryTransfer(E e, long timeout, TimeUnit unit)	Transfers the element to a consumer if it is possible to do so before the timeout elapses.

从类继承的方法 java.util.AbstractCollection

containsAll, removeAll, retainAll, toArray, toArray, toString

从类继承的方法 java.util.AbstractQueue

addAll, clear, element, remove

从接口继承的方法 java.util.Collection

addAll, clear, containsAll, equals, hashCode, parallelStream, removeAll, removeIf, retainAll, stream, toArray, toArray

从接口继承的方法 java.lang.Iterable

forEach

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

从接口继承的方法 java.util.Queue

element, remove

构造器详细资料

LinkedTransferQueue

public LinkedTransferQueue()

Creates an initially empty LinkedTransferQueue.

LinkedTransferQueue

public LinkedTransferQueue(Collection<? extends E> c)

Creates a LinkedTransferQueue initially containing the elements of the given collection, added in traversal order of the collection's iterator.

参数:

c - the collection of elements to initially contain

抛出:

NullPointerException - if the specified collection or any of its elements are null

方法详细资料

spliterator

public Spliterator<E> spliterator()

Returns a Spliterator over the elements in this queue.

The returned spliterator is weakly consistent.

The Spliterator reports Spliterator#CONCURRENT, Spliterator#ORDERED, and Spliterator#NONNULL.

指定者:

spliterator 在接口中 Collection<E>

指定者:

spliterator 在接口中 Iterable<E>

返回:

a Spliterator over the elements in this queue

从以下版本开始:

1.8

put

public void put(E e)

Inserts the specified element at the tail of this queue. As the queue is unbounded, this method will never block.

指定者:

put 在接口中 BlockingQueue<E>

参数:

e - the element to add

抛出:

NullPointerException - if the specified element is null

offer

public boolean offer(E e,
                     long timeout,
                     TimeUnit unit)

Inserts the specified element at the tail of this queue. As the queue is unbounded, this method will never block or return false.

指定者:

offer 在接口中 BlockingQueue<E>

参数:

e - the element to add

timeout - how long to wait before giving up, in units of unit

unit - a TimeUnit determining how to interpret the timeout parameter

返回:

true (as specified by BlockingQueue.offer)

抛出:

NullPointerException - if the specified element is null

offer

public boolean offer(E e)

Inserts the specified element at the tail of this queue. As the queue is unbounded, this method will never return false.

指定者:

offer 在接口中 BlockingQueue<E>

指定者:

offer 在接口中 Queue<E>

参数:

e - the element to add

返回:

true (as specified by Queue#offer)

抛出:

NullPointerException - if the specified element is null

add

public boolean add(E e)

Inserts the specified element at the tail of this queue. As the queue is unbounded, this method will never throw IllegalStateException or return false.

指定者:

add 在接口中 BlockingQueue<E>

指定者:

add 在接口中 Collection<E>

指定者:

add 在接口中 Queue<E>

覆盖:

add 在类中 AbstractQueue<E>

参数:

e - the element to add

返回:

true (as specified by Collection#add)

抛出:

NullPointerException - if the specified element is null

tryTransfer

public boolean tryTransfer(E e)

Transfers the element to a waiting consumer immediately, if possible.

More precisely, transfers the specified element immediately if there exists a consumer already waiting to receive it (in take() or timed poll), otherwise returning false without enqueuing the element.

指定者:

tryTransfer 在接口中 TransferQueue<E>

参数:

e - the element to transfer

返回:

true if the element was transferred, else false

抛出:

NullPointerException - if the specified element is null

transfer

public void transfer(E e)
              throws InterruptedException

Transfers the element to a consumer, waiting if necessary to do so.

More precisely, transfers the specified element immediately if there exists a consumer already waiting to receive it (in take() or timed poll), else inserts the specified element at the tail of this queue and waits until the element is received by a consumer.

指定者:

transfer 在接口中 TransferQueue<E>

参数:

e - the element to transfer

抛出:

NullPointerException - if the specified element is null

InterruptedException - if interrupted while waiting, in which case the element is not left enqueued

tryTransfer

public boolean tryTransfer(E e,
                           long timeout,
                           TimeUnit unit)
                    throws InterruptedException

Transfers the element to a consumer if it is possible to do so before the timeout elapses.

More precisely, transfers the specified element immediately if there exists a consumer already waiting to receive it (in take() or timed poll), else inserts the specified element at the tail of this queue and waits until the element is received by a consumer, returning false if the specified wait time elapses before the element can be transferred.

指定者:

tryTransfer 在接口中 TransferQueue<E>

参数:

e - the element to transfer

timeout - how long to wait before giving up, in units of unit

unit - a TimeUnit determining how to interpret the timeout parameter

返回:

true if successful, or false if the specified waiting time elapses before completion, in which case the element is not left enqueued

抛出:

NullPointerException - if the specified element is null

InterruptedException - if interrupted while waiting, in which case the element is not left enqueued

take

public E take()
       throws InterruptedException

从接口复制的说明: BlockingQueue

Retrieves and removes the head of this queue, waiting if necessary until an element becomes available.

指定者:

take 在接口中 BlockingQueue<E>

返回:

the head of this queue

抛出:

InterruptedException - if interrupted while waiting

poll

public E poll(long timeout,
              TimeUnit unit)
       throws InterruptedException

从接口复制的说明: BlockingQueue

Retrieves and removes the head of this queue, waiting up to the specified wait time if necessary for an element to become available.

指定者:

poll 在接口中 BlockingQueue<E>

参数:

timeout - how long to wait before giving up, in units of unit

unit - a TimeUnit determining how to interpret the timeout parameter

返回:

the head of this queue, or null if the specified waiting time elapses before an element is available

抛出:

InterruptedException - if interrupted while waiting

poll

public E poll()

从接口复制的说明: Queue

Retrieves and removes the head of this queue, or returns null if this queue is empty.

指定者:

poll 在接口中 Queue<E>

返回:

the head of this queue, or null if this queue is empty

drainTo

public int drainTo(Collection<? super E> c)

从接口复制的说明: BlockingQueue

Removes 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 collection c may result in elements being in neither, either or both collections when the associated exception is thrown. Attempts to drain a queue to itself result in IllegalArgumentException. Further, the behavior of this operation is undefined if the specified collection is modified while the operation is in progress.

指定者:

drainTo 在接口中 BlockingQueue<E>

参数:

c - the collection to transfer elements into

返回:

the number of elements transferred

抛出:

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

drainTo

public int drainTo(Collection<? super E> c,
                   int maxElements)

从接口复制的说明: BlockingQueue

Removes 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 collection c may result in elements being in neither, either or both collections when the associated exception is thrown. Attempts to drain a queue to itself result in IllegalArgumentException. Further, the behavior of this operation is undefined if the specified collection is modified while the operation is in progress.

指定者:

drainTo 在接口中 BlockingQueue<E>

参数:

c - the collection to transfer elements into

maxElements - the maximum number of elements to transfer

返回:

the number of elements transferred

抛出:

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

iterator

public Iterator<E> iterator()

Returns an iterator over the elements in this queue in proper sequence. The elements will be returned in order from first (head) to last (tail).

The returned iterator is weakly consistent.

指定者:

iterator 在接口中 Collection<E>

指定者:

iterator 在接口中 Iterable<E>

指定者:

iterator 在类中 AbstractCollection<E>

返回:

an iterator over the elements in this queue in proper sequence

peek

public E peek()

从接口复制的说明: Queue

Retrieves, but does not remove, the head of this queue, or returns null if this queue is empty.

指定者:

peek 在接口中 Queue<E>

返回:

the head of this queue, or null if this queue is empty

isEmpty

public boolean isEmpty()

Returns true if this queue contains no elements.

指定者:

isEmpty 在接口中 Collection<E>

覆盖:

isEmpty 在类中 AbstractCollection<E>

返回:

true if this queue contains no elements

hasWaitingConsumer

public boolean hasWaitingConsumer()

从接口复制的说明: TransferQueue

Returns true if there is at least one consumer waiting to receive an element via BlockingQueue.take() or timed poll. The return value represents a momentary state of affairs.

指定者:

hasWaitingConsumer 在接口中 TransferQueue<E>

返回:

true if there is at least one waiting consumer

size

public int size()

Returns the number of elements in this queue. If this queue contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

Beware that, unlike in most collections, this method is NOT a constant-time operation. Because of the asynchronous nature of these queues, determining the current number of elements requires an O(n) traversal.

指定者:

size 在接口中 Collection<E>

指定者:

size 在类中 AbstractCollection<E>

返回:

the number of elements in this queue

getWaitingConsumerCount

public int getWaitingConsumerCount()

从接口复制的说明: TransferQueue

Returns an estimate of the number of consumers waiting to receive elements via BlockingQueue.take() or timed poll. The return value is an approximation of a momentary state of affairs, that may be inaccurate if consumers have completed or given up waiting. The value may be useful for monitoring and heuristics, but not for synchronization control. Implementations of this method are likely to be noticeably slower than those for TransferQueue.hasWaitingConsumer().

指定者:

getWaitingConsumerCount 在接口中 TransferQueue<E>

返回:

the number of consumers waiting to receive elements

remove

public boolean remove(Object o)

Removes a single instance of the specified element from this queue, if it is present. More formally, removes an element e such that o.equals(e), if this queue contains one or more such elements. Returns true if this queue contained the specified element (or equivalently, if this queue changed as a result of the call).

指定者:

remove 在接口中 BlockingQueue<E>

指定者:

remove 在接口中 Collection<E>

覆盖:

remove 在类中 AbstractCollection<E>

参数:

o - element to be removed from this queue, if present

返回:

true if this queue changed as a result of the call

contains

public boolean contains(Object o)

Returns true if this queue contains the specified element. More formally, returns true if and only if this queue contains at least one element e such that o.equals(e).

指定者:

contains 在接口中 BlockingQueue<E>

指定者:

contains 在接口中 Collection<E>

覆盖:

contains 在类中 AbstractCollection<E>

参数:

o - object to be checked for containment in this queue

返回:

true if this queue contains the specified element

remainingCapacity

public int remainingCapacity()

Always returns Integer.MAX_VALUE because a LinkedTransferQueue is not capacity constrained.

指定者:

remainingCapacity 在接口中 BlockingQueue<E>

返回:

Integer.MAX_VALUE (as specified by BlockingQueue.remainingCapacity)