程序包 java.util.concurrent

类 LinkedBlockingQueue<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractQueue<E>

java.util.concurrent.LinkedBlockingQueue<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>, Queue<E>

public class LinkedBlockingQueue<E>
extends AbstractQueue<E>
implements BlockingQueue<E>, Serializable

An optionally-bounded BlockingQueue based on linked nodes. This queue orders elements FIFO (first-in-first-out). The head of the queue is that element that has been on the queue the longest time. The tail of the queue is that element that has been on the queue the shortest time. New elements are inserted at the tail of the queue, and the queue retrieval operations obtain elements at the head of the queue. Linked queues typically have higher throughput than array-based queues but less predictable performance in most concurrent applications.

The optional capacity bound constructor argument serves as a way to prevent excessive queue expansion. The capacity, if unspecified, is equal to Integer#MAX_VALUE. Linked nodes are dynamically created upon each insertion unless this would bring the queue above capacity.

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.

从以下版本开始:

1.5

另请参阅:

序列化表格

构造器概要

构造器

构造器	说明
LinkedBlockingQueue()	Creates a LinkedBlockingQueue with a capacity of Integer#MAX_VALUE.
LinkedBlockingQueue(int capacity)	Creates a LinkedBlockingQueue with the given (fixed) capacity.
LinkedBlockingQueue(Collection<? extends E> c)	Creates a LinkedBlockingQueue with a capacity of Integer#MAX_VALUE, 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
void	clear()	Atomically removes all of the elements from 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.
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 if it is possible to do so immediately without exceeding the queue's capacity, returning true upon success and false if this queue is full.
boolean	offer(E e, long timeout, TimeUnit unit)	Inserts the specified element at the tail of this queue, waiting if necessary up to the specified wait time for space to become available.
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, waiting if necessary for space to become available.
int	remainingCapacity()	Returns the number of additional elements that this queue can ideally (in the absence of memory or resource constraints) accept without blocking.
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.
Object[]	toArray()	Returns an array containing all of the elements in this queue, in proper sequence.
<T> T[]	toArray(T[] a)	Returns an array containing all of the elements in this queue, in proper sequence; the runtime type of the returned array is that of the specified array.
String	toString()	Returns a string representation of this collection.

从类继承的方法 java.util.AbstractCollection

containsAll, isEmpty, removeAll, retainAll

从类继承的方法 java.util.AbstractQueue

add, addAll, element, remove

从接口继承的方法 java.util.concurrent.BlockingQueue

add

从接口继承的方法 java.util.Collection

addAll, containsAll, equals, hashCode, isEmpty, parallelStream, removeAll, removeIf, retainAll, stream

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

LinkedBlockingQueue

public LinkedBlockingQueue()

Creates a LinkedBlockingQueue with a capacity of Integer#MAX_VALUE.

LinkedBlockingQueue

public LinkedBlockingQueue(int capacity)

Creates a LinkedBlockingQueue with the given (fixed) capacity.

参数:

capacity - the capacity of this queue

抛出:

IllegalArgumentException - if capacity is not greater than zero

LinkedBlockingQueue

public LinkedBlockingQueue(Collection<? extends E> c)

Creates a LinkedBlockingQueue with a capacity of Integer#MAX_VALUE, 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

size

public int size()

Returns the number of elements in this queue.

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

remainingCapacity

public int remainingCapacity()

Returns the number of additional elements that this queue can ideally (in the absence of memory or resource constraints) accept without blocking. This is always equal to the initial capacity of this queue less the current size of this queue.

Note that you cannot always tell if an attempt to insert an element will succeed by inspecting remainingCapacity because it may be the case that another thread is about to insert or remove an element.

指定者:

remainingCapacity 在接口中 BlockingQueue<E>

返回:

the remaining capacity

put

public void put(E e)
         throws InterruptedException

Inserts the specified element at the tail of this queue, waiting if necessary for space to become available.

指定者:

put 在接口中 BlockingQueue<E>

参数:

e - the element to add

抛出:

InterruptedException - if interrupted while waiting

NullPointerException - if the specified element is null

offer

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

Inserts the specified element at the tail of this queue, waiting if necessary up to the specified wait time for space to become available.

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 if successful, or false if the specified waiting time elapses before space is available

抛出:

InterruptedException - if interrupted while waiting

NullPointerException - if the specified element is null

offer

public boolean offer(E e)

Inserts the specified element at the tail of this queue if it is possible to do so immediately without exceeding the queue's capacity, returning true upon success and false if this queue is full. When using a capacity-restricted queue, this method is generally preferable to method BlockingQueue#add, which can fail to insert an element only by throwing an exception.

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 if the element was added to this queue, else false

抛出:

NullPointerException - if the specified element is null

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

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

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

toArray

public Object[] toArray()

Returns an array containing all of the elements in this queue, in proper sequence.

The returned array will be "safe" in that no references to it are maintained by this queue. (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.

指定者:

toArray 在接口中 Collection<E>

覆盖:

toArray 在类中 AbstractCollection<E>

返回:

an array containing all of the elements in this queue

toArray

public <T> T[] toArray(T[] a)

Returns an array containing all of the elements in this queue, in proper sequence; the runtime type of the returned array is that of the specified array. If the queue 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 queue.

If this queue fits in the specified array with room to spare (i.e., the array has more elements than this queue), the element in the array immediately following the end of the queue 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 x is a queue known to contain only strings. The following code can be used to dump the queue into a newly allocated array of String:

 String[] y = x.toArray(new String[0]);

Note that toArray(new Object[0]) is identical in function to toArray().

指定者:

toArray 在接口中 Collection<E>

覆盖:

toArray 在类中 AbstractCollection<E>

类型参数:

T - the runtime type of the array to contain the collection

参数:

a - the array into which the elements of the queue are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose

返回:

an array containing all of the elements in this queue

抛出:

ArrayStoreException - if the runtime type of the specified array is not a supertype of the runtime type of every element in this queue

NullPointerException - if the specified array is null

toString

public String toString()

从类复制的说明: AbstractCollection

Returns a string representation of this collection. The string representation consists of a list of the collection's elements in the order they are returned by its iterator, enclosed in square brackets ("[]"). Adjacent elements are separated by the characters ", " (comma and space). Elements are converted to strings as by String#valueOf(Object).

覆盖:

toString 在类中 AbstractCollection<E>

返回:

a string representation of this collection

clear

public void clear()

Atomically removes all of the elements from this queue. The queue will be empty after this call returns.

指定者:

clear 在接口中 Collection<E>

覆盖:

clear 在类中 AbstractQueue<E>

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:

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

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:

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

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

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