ArrayBlockingQueue

public class ArrayBlockingQueue extends AbstractQueue<E>
implements BlockingQueue<E> Serializable

A bounded {@linkplain BlockingQueue 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 Constructor Summary

ArrayBlockingQueue(int capacity)
Creates an ArrayBlockingQueue with the given (fixed) capacity and default access policy.
ArrayBlockingQueue(int capacity, boolean fair)
Creates an ArrayBlockingQueue with the given (fixed) capacity and the specified access policy.
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.

Public Method Summary

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.
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, int maxElements)
Removes at most the given number of available elements from this queue and adds them to the given collection.
int
drainTo(Collection<? super E> c)
Removes all 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 up to the specified wait time for space to become available if the queue is full.
E
peek()
Retrieves, but does not remove, 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.
E
poll()
Retrieves and removes the head of this queue, or returns null if this queue is empty.
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.
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.
<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.
Object[]
toArray()
Returns an array containing all of the elements in this queue, in proper sequence.
String
toString()
Returns a string representation of this collection.

Inherited Method Summary