| 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
changed. 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 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Creates an
ArrayBlockingQueue with the given (fixed)
capacity and default access policy.
| |||||||||||
Creates an
ArrayBlockingQueue with the given (fixed)
capacity and the specified access policy.
| |||||||||||
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.
| |||||||||||
| Public Methods | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
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.
| |||||||||||
Atomically removes all of the elements from this queue.
| |||||||||||
Returns
true if this queue contains the specified element.
| |||||||||||
Removes at most the given number of available elements from
this queue and adds them to the given collection.
| |||||||||||
Removes all available elements from this queue and adds them
to the given collection.
| |||||||||||
Returns an iterator over the elements in this queue in proper sequence.
| |||||||||||
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.
| |||||||||||
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.
| |||||||||||
Retrieves, but does not remove, the head of this queue,
or returns null if this queue is empty.
| |||||||||||
Retrieves and removes the head of this queue,
or returns null if this queue is empty.
| |||||||||||
Retrieves and removes the head of this queue, waiting up to the
specified wait time if necessary for an element to become available.
| |||||||||||
Inserts the specified element at the tail of this queue, waiting
for space to become available if the queue is full.
| |||||||||||
Returns the number of additional elements that this queue can ideally
(in the absence of memory or resource constraints) accept without
blocking.
| |||||||||||
Removes a single instance of the specified element from this queue,
if it is present.
| |||||||||||
Returns the number of elements in this queue.
| |||||||||||
Retrieves and removes the head of this queue, waiting if necessary
until an element becomes available.
| |||||||||||
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.
| |||||||||||
Returns an array containing all of the elements in this queue, in
proper sequence.
| |||||||||||
Returns the string representation of this
Collection.
| |||||||||||
|
[Expand]
Inherited Methods | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.util.AbstractQueue
| |||||||||||
|
From class
java.util.AbstractCollection
| |||||||||||
|
From class
java.lang.Object
| |||||||||||
|
From interface
java.util.Queue
| |||||||||||
|
From interface
java.util.Collection
| |||||||||||
|
From interface
java.util.concurrent.BlockingQueue
| |||||||||||
|
From interface
java.lang.Iterable
| |||||||||||
Creates an ArrayBlockingQueue with the given (fixed)
capacity and default access policy.
| capacity | the capacity of this queue |
|---|
| IllegalArgumentException | if capacity < 1
|
|---|
Creates an ArrayBlockingQueue with the given (fixed)
capacity and the specified access policy.
| capacity | the capacity of this queue |
|---|---|
| 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 < 1
|
|---|
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 |
|---|---|
| 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. |
|---|---|
| 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 |
|---|
Developers
true (as specified by add(E))| IllegalStateException | if this queue is full |
|---|---|
| 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 |
|---|
true if this queue contains the specified element
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 |
|---|---|
| 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 |
|---|
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.
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 |
|---|
true if the element was added to this queue, else
false| NullPointerException | if the specified element is null |
|---|
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 |
|---|---|
| timeout | how long to wait before giving up, in units of
unit |
| unit | a TimeUnit determining how to interpret the
timeout parameter |
true if successful, or false if
the specified waiting time elapses before space is availableRetrieves, but does not remove, the head of this queue, or returns null if this queue is empty.
Retrieves and removes the head of this queue, or returns null if this queue is empty.
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 |
|---|---|
| unit | a TimeUnit determining how to interpret the
timeout parameter |
null if the
specified waiting time elapses before an element is available| InterruptedException |
|---|
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 |
|---|
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).
Removal of interior elements in circular array based queues is an intrinsically slow and disruptive operation, so should be undertaken only in exceptional circumstances, ideally only when the queue is known not to be accessible by other threads.
| o | element to be removed from this queue, if present |
|---|
true if this queue changed as a result of the call
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 |
|---|
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 |
|---|
| 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 |
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.