java.lang.Object | |||
↳ | java.util.AbstractCollection<E> | ||
↳ | java.util.AbstractQueue<E> | ||
↳ | java.util.concurrent.ArrayBlockingQueue<E> |
A bounded blocking queue
backed by an
array. 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.
This is a classic "bounded buffer", in which a fixed-sized array holds elements inserted by producers and extracted by consumers. Once created, the capacity cannot be increased. Attempts to put an element into a full queue will result in the operation blocking; attempts to take an element from an empty queue will similarly block.
This class supports an optional fairness policy for ordering waiting producer and consumer threads. By default, this ordering is not guaranteed. However, a queue constructed with fairness set to true grants threads access in FIFO order. Fairness generally decreases throughput but reduces variability and avoids starvation.
This class and its iterator implement all of the
optional methods of the Collection
and Iterator
interfaces.
Public Constructors | |||||||||||
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Creates an ArrayBlockingQueue with the given (fixed)
capacity and default access policy.
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Creates an ArrayBlockingQueue with the given (fixed)
capacity and the specified access policy.
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Creates an ArrayBlockingQueue with the given (fixed)
capacity, the specified access policy and initially containing the
elements of the given collection,
added in traversal order of the collection's iterator.
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Public Methods | |||||||||||
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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 throwing an
IllegalStateException if this queue is full.
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Atomically removes all of the elements from this queue.
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Returns true if this queue contains the specified element.
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Removes at most the given number of available elements from
this queue and adds them to the given collection.
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Removes all available elements from this queue and adds them
to the given collection.
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Returns an iterator over the elements in this queue in proper sequence.
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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.
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Inserts the specified element at the tail of this queue, waiting
up to the specified wait time for space to become available if
the queue is full.
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Gets but does not remove the element at the head of the queue.
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Gets and removes the element at the head of the queue, or returns
null if there is no element in the queue. | |||||||||||
Retrieves and removes the head of this queue, waiting up to the
specified wait time if necessary for an element to become available.
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Inserts the specified element at the tail of this queue, waiting
for space to become available if the queue is full.
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Returns the number of additional elements that this queue can ideally
(in the absence of memory or resource constraints) accept without
blocking.
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Removes a single instance of the specified element from this queue,
if it is present.
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Returns the number of elements in this queue.
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Retrieves and removes the head of this queue, waiting if necessary
until an element becomes available.
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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.
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Returns an array containing all of the elements in this queue, in
proper sequence.
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Returns the string representation of this
Collection . |
[Expand]
Inherited Methods | |||||||||||
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From class java.util.AbstractQueue
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From class java.util.AbstractCollection
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From class java.lang.Object
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From interface java.lang.Iterable
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From interface java.util.Collection
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From interface java.util.Queue
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From interface java.util.concurrent.BlockingQueue
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Creates an ArrayBlockingQueue with the given (fixed) capacity and default access policy.
capacity | the capacity of this queue |
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IllegalArgumentException | if capacity is less than 1 |
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Creates an ArrayBlockingQueue with the given (fixed) capacity and the specified access policy.
capacity | the capacity of this queue |
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fair | if true then queue accesses for threads blocked on insertion or removal, are processed in FIFO order; if false the access order is unspecified. |
IllegalArgumentException | if capacity is less than 1 |
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Creates an ArrayBlockingQueue with the given (fixed) capacity, the specified access policy and initially containing the elements of the given collection, added in traversal order of the collection's iterator.
capacity | the capacity of this queue |
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fair | if true then queue accesses for threads blocked on insertion or removal, are processed in FIFO order; if false the access order is unspecified. |
c | the collection of elements to initially contain |
IllegalArgumentException | if capacity is less than c.size(), or less than 1. |
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NullPointerException | if the specified collection or any of its elements are null |
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 throwing an IllegalStateException if this queue is full.
e | the element to add |
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add(E)
)IllegalStateException | if this queue is full |
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NullPointerException | if the specified element is null |
Atomically removes all of the elements from this queue. The queue will be empty after this call returns.
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).
o | object to be checked for containment in this queue |
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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.
c | the collection to transfer elements into |
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maxElements | the maximum number of elements to transfer |
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.
c | the collection to transfer elements into |
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Returns an iterator over the elements in this queue in proper sequence.
The returned Iterator is a "weakly consistent" iterator that
will never throw ConcurrentModificationException
,
and guarantees to traverse elements as they existed upon
construction of the iterator, and may (but is not guaranteed to)
reflect any modifications subsequent to construction.
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. This method is generally preferable to method add(E)
,
which can fail to insert an element only by throwing an exception.
e | the element to add |
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NullPointerException | if the specified element is null |
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Inserts the specified element at the tail of this queue, waiting up to the specified wait time for space to become available if the queue is full.
e | the element to add |
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timeout | how long to wait before giving up, in units of unit |
unit | a TimeUnit determining how to interpret the timeout parameter |
Gets but does not remove the element at the head of the queue.
null
if there is
no element in the queue.
Gets and removes the element at the head of the queue, or returns null
if there is no element in the queue.
null
if there is
no element in the queue.
Retrieves and removes the head of this queue, waiting up to the specified wait time if necessary for an element to become available.
timeout | how long to wait before giving up, in units of unit |
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unit | a TimeUnit determining how to interpret the timeout parameter |
InterruptedException |
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Inserts the specified element at the tail of this queue, waiting for space to become available if the queue is full.
e | the element to add |
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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.
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).
o | element to be removed from this queue, if present |
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Returns the number of elements in this queue.
Retrieves and removes the head of this queue, waiting if necessary until an element becomes available.
InterruptedException |
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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().
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 |
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ArrayStoreException | if the runtime type of the specified array is not a supertype of the runtime type of every element in this queue |
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NullPointerException | if the specified array is null |
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.
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).
Collection
.