| java.util.concurrent.ArrayBlockingQueue
| ArrayBlockingQueue | | public class ArrayBlockingQueue extends AbstractQueue implements BlockingQueue<E>,java.io.Serializable(Code) | | A bounded
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.
This class is a member of the
Java Collections Framework.
since:
1.5
author:
Doug Lea<
Parameters:
E - > the type of elements held in this collection |
| Constructor Summary | |
| public | ArrayBlockingQueue(int capacity)
Creates an ArrayBlockingQueue with the given (fixed)
capacity and default access policy. | | public | ArrayBlockingQueue(int capacity, boolean fair)
Creates an ArrayBlockingQueue with the given (fixed)
capacity and the specified access policy. | | public | ArrayBlockingQueue(int capacity, boolean fair, Collection<? extends E> c)
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. |
| Method Summary | |
| public boolean | add(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 throwing an
IllegalStateException if this queue is full. | | public void | clear()
Atomically removes all of the elements from this queue. | | public boolean | contains(Object o)
Returns true if this queue contains the specified element. | | public int | drainTo(Collection<? super E> c)
| | public int | drainTo(Collection<? super E> c, int maxElements)
| | final int | inc(int i)
Circularly increment i. | | public Iterator<E> | iterator()
Returns an iterator over the elements in this queue in proper sequence. | | 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. | | public boolean | offer(E e, long timeout, TimeUnit unit)
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. | | public E | peek()
| | public E | poll()
| | public E | poll(long timeout, TimeUnit unit)
| | public void | put(E e)
Inserts the specified element at the tail of this queue, waiting
for space to become available if the queue is full. | | 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. | | public boolean | remove(Object o)
Removes a single instance of the specified element from this queue,
if it is present. | | void | removeAt(int i)
Utility for remove and iterator.remove: Delete item at position i. | | public int | size()
Returns the number of elements in this queue. | | public E | take()
| | 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. | | public 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. | | public String | toString()
|
| ArrayBlockingQueue | | public ArrayBlockingQueue(int capacity)(Code) | | Creates an ArrayBlockingQueue with the given (fixed)
capacity and default access policy.
Parameters:
capacity - the capacity of this queue
throws:
IllegalArgumentException - if capacity is less than 1 |
| ArrayBlockingQueue | | public ArrayBlockingQueue(int capacity, boolean fair)(Code) | | Creates an ArrayBlockingQueue with the given (fixed)
capacity and the specified access policy.
Parameters:
capacity - the capacity of this queue
Parameters:
fair - if true then queue accesses for threads blockedon insertion or removal, are processed in FIFO order;if false the access order is unspecified.
throws:
IllegalArgumentException - if capacity is less than 1 |
| ArrayBlockingQueue | | public ArrayBlockingQueue(int capacity, boolean fair, Collection<? extends E> c)(Code) | | 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.
Parameters:
capacity - the capacity of this queue
Parameters:
fair - if true then queue accesses for threads blockedon insertion or removal, are processed in FIFO order;if false the access order is unspecified.
Parameters:
c - the collection of elements to initially contain
throws:
IllegalArgumentException - if capacity is less thanc.size(), or less than 1.
throws:
NullPointerException - if the specified collection or anyof its elements are null |
| add | | public boolean add(E e)(Code) | | 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.
Parameters:
e - the element to add true (as specified by Collection.add)
throws:
IllegalStateException - if this queue is full
throws:
NullPointerException - if the specified element is null |
| clear | | public void clear()(Code) | | Atomically removes all of the elements from this queue.
The queue will be empty after this call returns.
|
| contains | | public boolean contains(Object o)(Code) | | 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).
Parameters:
o - object to be checked for containment in this queue true if this queue contains the specified element |
| inc | | final int inc(int i)(Code) | | Circularly increment i.
|
| iterator | | public Iterator<E> iterator()(Code) | | 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.
an iterator over the elements in this queue in proper sequence |
| offer | | public boolean offer(E e)(Code) | | 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
ArrayBlockingQueue.add ,
which can fail to insert an element only by throwing an exception.
throws:
NullPointerException - if the specified element is null |
| remainingCapacity | | public int remainingCapacity()(Code) | | 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.
|
| remove | | public boolean remove(Object o)(Code) | | 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).
Parameters:
o - element to be removed from this queue, if present true if this queue changed as a result of the call |
| removeAt | | void removeAt(int i)(Code) | | Utility for remove and iterator.remove: Delete item at position i.
Call only when holding lock.
|
| size | | public int size()(Code) | | Returns the number of elements in this queue.
the number of elements in this queue |
| toArray | | public Object[] toArray()(Code) | | 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.
an array containing all of the elements in this queue |
| toArray | | public T[] toArray(T[] a)(Code) | | 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
ArrayBlockingQueue.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().
Parameters:
a - the array into which the elements of the queue are tobe stored, if it is big enough; otherwise, a new array of thesame runtime type is allocated for this purpose an array containing all of the elements in this queue
throws:
ArrayStoreException - if the runtime type of the specified arrayis not a supertype of the runtime type of every element inthis queue
throws:
NullPointerException - if the specified array is null |
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