ArrayBlockingQueue

open class ArrayBlockingQueue<E : Any!> : AbstractQueue<E>, BlockingQueue<E>, Serializable
kotlin.Any
   ↳ java.util.AbstractCollection<E>
   ↳ java.util.AbstractQueue<E>
   ↳ java.util.concurrent.ArrayBlockingQueue

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 interfaces.

Summary

Public constructors
<init>(capacity: Int)

Creates an ArrayBlockingQueue with the given (fixed) capacity and default access policy.

<init>(capacity: Int, fair: Boolean)

Creates an ArrayBlockingQueue with the given (fixed) capacity and the specified access policy.

<init>(capacity: Int, fair: Boolean, c: MutableCollection<out E>!)

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
open Boolean
contains(element: E)

Returns true if this queue contains the specified element.

open Unit

Atomically removes all of the elements from this queue.

open E

open Boolean
add(element: 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.

open 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.

open Boolean
offer(e: E, timeout: Long, unit: TimeUnit!)

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.

open MutableIterator<E>

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

open E

open Spliterator<E>

Returns a Spliterator over the elements in this queue.

open Array<Any!>!

Returns an array containing all of the elements in this queue, in proper sequence.

open Array<T>!
toArray(a: Array<T>!)

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.

open Unit
put(e: E)

Inserts the specified element at the tail of this queue, waiting for space to become available if the queue is full.

open String

open Boolean
remove(element: E)

Removes a single instance of the specified element from this queue, if it is present.

open Int

open Int
drainTo(c: MutableCollection<in E>!, maxElements: Int)

open Int

Returns the number of additional elements that this queue can ideally (in the absence of memory or resource constraints) accept without blocking.

open E

open E
poll(timeout: Long, unit: TimeUnit!)

Inherited functions
Properties
open Int

Returns the number of elements in this queue.

Inherited properties

Public constructors

<init>

ArrayBlockingQueue(capacity: Int)

Creates an ArrayBlockingQueue with the given (fixed) capacity and default access policy.

Parameters
capacity Int: the capacity of this queue
Exceptions
IllegalArgumentException if capacity < 1

<init>

ArrayBlockingQueue(capacity: Int, fair: Boolean)

Creates an ArrayBlockingQueue with the given (fixed) capacity and the specified access policy.

Parameters
capacity Int: the capacity of this queue
fair Int: if true then queue accesses for threads blocked on insertion or removal, are processed in FIFO order; if false the access order is unspecified.
Exceptions
IllegalArgumentException if capacity < 1

<init>

ArrayBlockingQueue(capacity: Int, fair: Boolean, c: MutableCollection<out E>!)

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 Int: the capacity of this queue
fair Int: 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 Int: the collection of elements to initially contain
Exceptions
IllegalArgumentException if capacity is less than c.size(), or less than 1.
NullPointerException if the specified collection or any of its elements are null

Public methods

contains

open fun contains(element: E): Boolean

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 E: object to be checked for containment in this queue
Return
Boolean: true if this queue contains the specified element
Exceptions
ClassCastException if the class of the specified element is incompatible with this queue (optional)
NullPointerException if the specified element is null (optional)

clear

open fun clear(): Unit

Atomically removes all of the elements from this queue. The queue will be empty after this call returns.

Exceptions
UnsupportedOperationException if the clear operation is not supported by this collection

take

open fun take(): E

add

open fun add(element: E): Boolean

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 E: the element to add
Return
Boolean: true (as specified by Collection#add)
Exceptions
UnsupportedOperationException if the add operation is not supported by this collection
ClassCastException if the class of the specified element prevents it from being added to this queue
NullPointerException if the specified element is null
IllegalArgumentException if some property of the specified element prevents it from being added to this queue
IllegalStateException if this queue is full

offer

open fun offer(e: E): Boolean

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, which can fail to insert an element only by throwing an exception.

Parameters
e E: the element to add
Return
Boolean: true if the element was added to this queue, else false
Exceptions
ClassCastException if the class of the specified element prevents it from being added to this queue
NullPointerException if the specified element is null
IllegalArgumentException if some property of the specified element prevents it from being added to this queue

offer

open fun offer(e: E, timeout: Long, unit: TimeUnit!): Boolean

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.

Parameters
e E: the element to add
timeout E: how long to wait before giving up, in units of unit
unit E: a TimeUnit determining how to interpret the timeout parameter
Return
Boolean: true if successful, or false if the specified waiting time elapses before space is available
Exceptions
InterruptedException if interrupted while waiting
ClassCastException if the class of the specified element prevents it from being added to this queue
NullPointerException if the specified element is null
IllegalArgumentException if some property of the specified element prevents it from being added to this queue

iterator

open fun iterator(): MutableIterator<E>

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.

Return
MutableIterator<E>: an iterator over the elements in this queue in proper sequence

peek

open fun peek(): E

spliterator

added in API level 1.8
open fun spliterator(): Spliterator<E>

Returns a Spliterator over the elements in this queue.

The returned spliterator is weakly consistent.

The Spliterator reports Spliterator#CONCURRENT, Spliterator#ORDERED, and Spliterator#NONNULL.
Requires API level 24 (Android 7.0, Nougat)

Return
Spliterator<E>: a Spliterator over the elements in this queue

toArray

open fun toArray(): Array<Any!>!

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.

Return
Array<Any!>!: an array containing all of the elements in this queue

toArray

open fun <T : Any!> toArray(a: Array<T>!): Array<T>!

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().
Parameters
<T> Array<T>!: the runtime type of the array to contain the collection
a Array<T>!: 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
Return
Array<T>!: an array containing all of the elements in this queue
Exceptions
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

put

open fun put(e: E): Unit

Inserts the specified element at the tail of this queue, waiting for space to become available if the queue is full.

Parameters
e E: the element to add
Exceptions
InterruptedException if interrupted while waiting
ClassCastException if the class of the specified element prevents it from being added to this queue
NullPointerException if the specified element is null
IllegalArgumentException if some property of the specified element prevents it from being added to this queue

toString

open fun toString(): String

remove

open fun remove(element: E): Boolean

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.

Parameters
o E: element to be removed from this queue, if present
Return
Boolean: true if this queue changed as a result of the call
Exceptions
ClassCastException if the class of the specified element is incompatible with this queue (optional)
NullPointerException if the specified element is null (optional)
UnsupportedOperationException if the remove operation is not supported by this collection

drainTo

open fun drainTo(c: MutableCollection<in E>!): Int
Parameters
c MutableCollection<in E>!: the collection to transfer elements into
Return
Int: the number of elements transferred
Exceptions
UnsupportedOperationException if addition of elements is not supported by the specified collection
ClassCastException if the class of an element of this queue prevents it from being added to the specified collection
NullPointerException if the specified collection is null
IllegalArgumentException if the specified collection is this queue, or some property of an element of this queue prevents it from being added to the specified collection

drainTo

open fun drainTo(c: MutableCollection<in E>!, maxElements: Int): Int
Parameters
c MutableCollection<in E>!: the collection to transfer elements into
maxElements MutableCollection<in E>!: the maximum number of elements to transfer
Return
Int: the number of elements transferred
Exceptions
UnsupportedOperationException if addition of elements is not supported by the specified collection
ClassCastException if the class of an element of this queue prevents it from being added to the specified collection
NullPointerException if the specified collection is null
IllegalArgumentException if the specified collection is this queue, or some property of an element of this queue prevents it from being added to the specified collection

remainingCapacity

open fun remainingCapacity(): Int

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.

Return
Int: the remaining capacity

poll

open fun poll(): E

poll

open fun poll(timeout: Long, unit: TimeUnit!): E

Properties

size

open val size: Int

Returns the number of elements in this queue.

Return
Int: the number of elements in this queue