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>

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

An optionally-bounded blocking queue 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 implements all of the optional methods of the Collection and Iterator interfaces.

从以下版本开始：

1.5

作者：

Doug Lea

另请参见：

序列化表格

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构造方法摘要
LinkedBlockingQueue()            Creates a LinkedBlockingQueue with a capacity of Integer.MAX_VALUE.
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.
LinkedBlockingQueue(int capacity)            Creates a LinkedBlockingQueue with the given (fixed) capacity.

方法摘要
void	clear()            Removes all elements of the queue, leaving it empty.
int	drainTo(Collection<? super E> c)            Removes all available elements from this queue and adds them into 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 into the given collection.
Iterator<E>	iterator()            Returns an iterator over the elements in this queue in proper sequence.
boolean	offer(E o)            Inserts the specified element at the tail of this queue if possible, returning immediately if this queue is full.
boolean	offer(E o, 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()            Gets but does not remove the element at the head of the queue.
E	poll()            Gets and removes the element at the head of the queue, or returns null if there is no element in the queue.
E	poll(long timeout, TimeUnit unit)            Retrieves and removes the head of this queue, waiting if necessary up to the specified wait time if no elements are present on this queue.
void	put(E o)            Adds the specified element to the tail of this queue, waiting if necessary for space to become available.
int	remainingCapacity()            Returns the number of elements that this queue can ideally (in the absence of memory or resource constraints) accept without blocking.
boolean	remove(Object o)            Removes one instance of the specified object from this Collection if one is contained (optional).
int	size()            Returns the number of elements in this queue.
E	take()            Retrieves and removes the head of this queue, waiting if no elements are present on this queue.
Object[]	toArray()            Returns a new array containing all elements contained in this Collection.
<T> T[]	toArray(T[] a)            Returns an array containing all elements contained in this Collection.
String	toString()            Returns the string representation of this Collection.

从类 java.util.AbstractQueue 继承的方法
add, addAll, element, remove

从类 java.util.AbstractCollection 继承的方法
contains, containsAll, isEmpty, removeAll, retainAll

从类 java.lang.Object 继承的方法
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

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

从接口 java.util.Queue 继承的方法
element, remove

从接口 java.util.Collection 继承的方法
addAll, contains, containsAll, equals, hashCode, isEmpty, removeAll, retainAll

构造方法详细信息

LinkedBlockingQueue

public LinkedBlockingQueue()

Creates a LinkedBlockingQueue with a capacity of Integer.MAX_VALUE.

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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.

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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 c or any element within it is null

方法详细信息

size

public int size()

Returns the number of elements in this queue.

指定者：

接口 Collection<E> 中的 size

指定者：

类 AbstractCollection<E> 中的 size

返回：

the number of elements in this queue.

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remainingCapacity

public int remainingCapacity()

Returns the number of 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 add an element will succeed by inspecting remainingCapacity because it may be the case that a waiting consumer is ready to take an element out of an otherwise full queue.

指定者：

接口 BlockingQueue<E> 中的 remainingCapacity

返回：

the remaining capacity

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put

public void put(E o)

         throws InterruptedException

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

指定者：

接口 BlockingQueue<E> 中的 put

参数：

o - the element to add

抛出：

InterruptedException - if interrupted while waiting.

NullPointerException - if the specified element is null.

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offer

public boolean offer(E o,

                     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：

接口 BlockingQueue<E> 中的 offer

参数：

o - 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.

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offer

public boolean offer(E o)

Inserts the specified element at the tail of this queue if possible, returning immediately if this queue is full.

指定者：

接口 BlockingQueue<E> 中的 offer

指定者：

接口 Queue<E> 中的 offer

参数：

o - the element to add.

返回：

true if it was possible to add the element to this queue, else false

抛出：

NullPointerException - if the specified element is null

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take

public E take()

       throws InterruptedException

从接口 BlockingQueue 复制的描述

Retrieves and removes the head of this queue, waiting if no elements are present on this queue.

指定者：

接口 BlockingQueue<E> 中的 take

返回：

the head of this queue

抛出：

InterruptedException - if interrupted while waiting.

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poll

public E poll(long timeout,

              TimeUnit unit)

       throws InterruptedException

从接口 BlockingQueue 复制的描述

Retrieves and removes the head of this queue, waiting if necessary up to the specified wait time if no elements are present on this queue.

指定者：

接口 BlockingQueue<E> 中的 poll

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 present.

抛出：

InterruptedException - if interrupted while waiting.

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poll

public E poll()

从接口 Queue 复制的描述

Gets and removes the element at the head of the queue, or returns null if there is no element in the queue.

指定者：

接口 Queue<E> 中的 poll

返回：

the element at the head of the queue or null if there is no element in the queue.

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peek

public E peek()

从接口 Queue 复制的描述

Gets but does not remove the element at the head of the queue.

指定者：

接口 Queue<E> 中的 peek

返回：

the element at the head of the queue or null if there is no element in the queue.

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remove

public boolean remove(Object o)

从类 AbstractCollection 复制的描述

Removes one instance of the specified object from this Collection if one is contained (optional). This implementation iterates over this Collection and tests for each element e returned by the iterator, whether e is equal to the given object. If object != null then this test is performed using object.equals(e), otherwise using object == null. If an element equal to the given object is found, then the remove method is called on the iterator and true is returned, false otherwise. If the iterator does not support removing elements, an UnsupportedOperationException is thrown.

指定者：

接口 Collection<E> 中的 remove

覆盖：

类 AbstractCollection<E> 中的 remove

参数：

o - the object to remove.

返回：

true if this Collection is modified, false otherwise.

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toArray

public Object[] toArray()

从接口 Collection 复制的描述

Returns a new array containing all elements contained in this Collection. If the implementation has ordered elements it will return the element array in the same order as an iterator would return them. The array returned does not reflect any changes of the Collection. A new array is created even if the underlying data structure is already an array.

指定者：

接口 Collection<E> 中的 toArray

覆盖：

类 AbstractCollection<E> 中的 toArray

返回：

an array of the elements from this Collection.

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toArray

public <T> T[] toArray(T[] a)

从接口 Collection 复制的描述

Returns an array containing all elements contained in this Collection. If the specified array is large enough to hold the elements, the specified array is used, otherwise an array of the same type is created. If the specified array is used and is larger than this Collection, the array element following the Collection elements is set to null. If the implementation has ordered elements it will return the element array in the same order as an iterator would return them. toArray(new Object[0]) behaves exactly the same way as toArray() does.

指定者：

接口 Collection<E> 中的 toArray

覆盖：

类 AbstractCollection<E> 中的 toArray

参数：

a - the array.

返回：

an array of the elements from this Collection.

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toString

public String toString()

从类 AbstractCollection 复制的描述

Returns the string representation of this Collection. The presentation has a specific format. It is enclosed by square brackets ("[]"). Elements are separated by ', ' (comma and space).

覆盖：

类 AbstractCollection<E> 中的 toString

返回：

the string representation of this Collection.

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clear

public void clear()

从类 AbstractQueue 复制的描述

Removes all elements of the queue, leaving it empty.

指定者：

接口 Collection<E> 中的 clear

覆盖：

类 AbstractQueue<E> 中的 clear

另请参见：

AbstractCollection.iterator(), AbstractCollection.isEmpty(), AbstractCollection.size()

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drainTo

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

从接口 BlockingQueue 复制的描述

Removes all available elements from this queue and adds them into 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：

接口 BlockingQueue<E> 中的 drainTo

参数：

c - the collection to transfer elements into

返回：

the number of elements transferred.

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drainTo

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

                   int maxElements)

从接口 BlockingQueue 复制的描述

Removes at most the given number of available elements from this queue and adds them into 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 inIllegalArgumentException. Further, the behavior of this operation is undefined if the specified collection is modified while the operation is in progress.

指定者：

接口 BlockingQueue<E> 中的 drainTo

参数：

c - the collection to transfer elements into

maxElements - the maximum number of elements to transfer

返回：

the number of elements transferred.

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iterator

public Iterator<E> iterator()

Returns an iterator over the elements in this queue in proper sequence.The returned Iterator is a "weakly consistent" iterator thatwill never throw ConcurrentModificationException,and guarantees to traverse elements as they existed uponconstruction of the iterator, and may (but is not guaranteed to)reflect any modifications subsequent to construction.

指定者：

接口 Iterable<E> 中的 iterator

指定者：

接口 Collection<E> 中的 iterator

指定者：

类 AbstractCollection<E> 中的 iterator

返回：

an iterator over the elements in this queue in proper sequence.

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