ArrayBlockingQueue
open class ArrayBlockingQueue<E : Any!> : AbstractQueue<E>, BlockingQueue<E>, Serializable
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.
This class is a member of the Java Collections Framework.
Summary
| 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 |
| open 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.
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| open Unit |
Atomically removes all of the elements from this queue.
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| open Boolean |
Returns true if this queue contains the specified element.
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| open Int |
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| open Int |
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| open Unit |
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| open MutableIterator<E> |
Returns an iterator over the elements in this queue in proper sequence.
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| open 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.
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| open 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.
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| open E? |
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| open E? |
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| open E |
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| open Unit |
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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| open Int |
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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| open Boolean |
Removes a single instance of the specified element from this queue, if it is present.
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| open Boolean |
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| open Boolean |
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| open Boolean |
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| open Spliterator<E> |
Returns a Spliterator over the elements in this queue.
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| open E |
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| open Array<Any!> |
Returns an array containing all of the elements in this queue, in proper sequence.
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| open 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.
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| open String |
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| Inherited functions |
From class AbstractQueue
Boolean |
addAll(elements: Collection<E>)
Adds all of the elements in the specified collection to this queue. Attempts to addAll of 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.
This implementation iterates over the specified collection, and adds each element returned by the iterator to this queue, in turn. A runtime exception encountered while trying to add an element (including, in particular, a null element) may result in only some of the elements having been successfully added when the associated exception is thrown.
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E |
element()
Retrieves, but does not remove, the head of this queue. This method differs from peek only in that it throws an exception if this queue is empty.
This implementation returns the result of peek unless the queue is empty.
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E |
remove()
Retrieves and removes the head of this queue. This method differs from poll only in that it throws an exception if this queue is empty.
This implementation returns the result of poll unless the queue is empty.
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From class AbstractCollection
Boolean |
contains(element: E?)
Returns true if this collection contains the specified element. More formally, returns true if and only if this collection contains at least one element e such that Objects.equals(o, e).
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Boolean |
containsAll(elements: Collection<E>)
Returns true if this collection contains all of the elements in the specified collection.
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Boolean |
isEmpty()
Returns true if this collection contains no elements.
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MutableIterator<E> |
iterator()
Returns an iterator over the elements contained in this collection.
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Boolean |
remove(element: E?)
Removes a single instance of the specified element from this collection, if it is present (optional operation). More formally, removes an element e such that Objects.equals(o, e), if this collection contains one or more such elements. Returns true if this collection contained the specified element (or equivalently, if this collection changed as a result of the call).
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Boolean |
removeAll(elements: Collection<E>)
Removes all of this collection's elements that are also contained in the specified collection (optional operation). After this call returns, this collection will contain no elements in common with the specified collection.
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Boolean |
retainAll(elements: Collection<E>)
Retains only the elements in this collection that are contained in the specified collection (optional operation). In other words, removes from this collection all of its elements that are not contained in the specified collection.
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Array<Any!> |
toArray()
Returns an array containing all of the elements in this collection. If this collection makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order. The returned array's runtime component type is Object.
The returned array will be "safe" in that no references to it are maintained by this collection. (In other words, this method must allocate a new array even if this collection is backed by an array). The caller is thus free to modify the returned array.
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Array<T> |
toArray(a: Array<T>)
Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array. If the collection 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 collection.
If this collection fits in the specified array with room to spare (i.e., the array has more elements than this collection), the element in the array immediately following the end of the collection is set to null. (This is useful in determining the length of this collection only if the caller knows that this collection does not contain any null elements.)
If this collection makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order.
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String |
toString()
Returns a string representation of this collection. The string representation consists of a list of the collection's elements in the order they are returned by its iterator, enclosed in square brackets ("[]"). Adjacent elements are separated by the characters ", " (comma and space). Elements are converted to strings as by String.valueOf(Object).
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From class Queue
Boolean |
offer(e: E)
Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions. When using a capacity-restricted queue, this method is generally preferable to add, which can fail to insert an element only by throwing an exception.
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E? |
peek()
Retrieves, but does not remove, the head of this queue, or returns null if this queue is empty.
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E? |
poll()
Retrieves and removes the head of this queue, or returns null if this queue is empty.
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| Properties |
| open Int |
Returns the number of elements in this queue.
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Public constructors
ArrayBlockingQueue
ArrayBlockingQueue(capacity: Int)
Creates an ArrayBlockingQueue with the given (fixed) capacity and default access policy.
| Parameters |
capacity |
Int: the capacity of this queue |
| Exceptions |
java.lang.IllegalArgumentException |
if capacity < 1 |
ArrayBlockingQueue
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 |
Boolean: 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 |
java.lang.IllegalArgumentException |
if capacity < 1 |
ArrayBlockingQueue
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 |
Boolean: 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 |
MutableCollection<out E>!: the collection of elements to initially contain |
| Exceptions |
java.lang.IllegalArgumentException |
if capacity is less than c.size(), or less than 1. |
java.lang.NullPointerException |
if the specified collection or any of its elements are null |
Public methods
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 |
the element to add |
| Exceptions |
java.lang.UnsupportedOperationException |
if the add operation is not supported by this collection |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this queue |
java.lang.NullPointerException |
if the specified element is null |
java.lang.IllegalArgumentException |
if some property of the specified element prevents it from being added to this queue |
java.lang.IllegalStateException |
if this queue is full |
clear
open fun clear(): Unit
Atomically removes all of the elements from this queue. The queue will be empty after this call returns.
| Exceptions |
java.lang.UnsupportedOperationException |
if the clear operation is not supported by this collection |
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 |
object to be checked for containment in this queue |
| Return |
Boolean |
true if this queue contains the specified element |
| Exceptions |
java.lang.ClassCastException |
if the class of the specified element is incompatible with this queue (optional) |
java.lang.NullPointerException |
if the specified element is null (optional) |
drainTo
open fun drainTo(c: MutableCollection<in E>!): Int
| Return |
Int |
the number of elements transferred |
| Exceptions |
java.lang.UnsupportedOperationException |
if addition of elements is not supported by the specified collection |
java.lang.ClassCastException |
if the class of an element of this queue prevents it from being added to the specified collection |
java.lang.NullPointerException |
if the specified collection is null |
java.lang.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 |
Int: the maximum number of elements to transfer |
| Return |
Int |
the number of elements transferred |
| Exceptions |
java.lang.UnsupportedOperationException |
if addition of elements is not supported by the specified collection |
java.lang.ClassCastException |
if the class of an element of this queue prevents it from being added to the specified collection |
java.lang.NullPointerException |
if the specified collection is null |
java.lang.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 |
forEach
open fun forEach(action: Consumer<in E>): Unit
| Parameters |
action |
Consumer<in E>: The action to be performed for each element |
| Exceptions |
java.lang.NullPointerException |
if the specified action is null |
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 |
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 |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this queue |
java.lang.NullPointerException |
if the specified element is null |
java.lang.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 |
Long: how long to wait before giving up, in units of unit |
unit |
TimeUnit!: 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 |
java.lang.InterruptedException |
if interrupted while waiting |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this queue |
java.lang.NullPointerException |
if the specified element is null |
java.lang.IllegalArgumentException |
if some property of the specified element prevents it from being added to this queue |
peek
open fun peek(): E?
| Return |
E? |
the head of this queue, or null if this queue is empty |
poll
open fun poll(): E?
| Return |
E? |
the head of this queue, or null if this queue is empty |
poll
open fun poll(
timeout: Long,
unit: TimeUnit!
): E
| Parameters |
timeout |
Long: how long to wait before giving up, in units of unit |
unit |
TimeUnit!: a TimeUnit determining how to interpret the timeout parameter |
| Return |
E |
the head of this queue, or null if the specified waiting time elapses before an element is available |
| Exceptions |
java.lang.InterruptedException |
if interrupted while waiting |
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 |
java.lang.InterruptedException |
if interrupted while waiting |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this queue |
java.lang.NullPointerException |
if the specified element is null |
java.lang.IllegalArgumentException |
if some property of the specified element prevents it from being added to this queue |
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 |
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 |
element to be removed from this queue, if present |
| Return |
Boolean |
true if this queue changed as a result of the call |
| Exceptions |
java.lang.ClassCastException |
if the class of the specified element is incompatible with this queue (optional) |
java.lang.NullPointerException |
if the specified element is null (optional) |
java.lang.UnsupportedOperationException |
if the remove operation is not supported by this collection |
removeAll
open fun removeAll(elements: Collection<E>): Boolean
| Parameters |
c |
collection containing elements to be removed from this collection |
| Return |
Boolean |
true if this collection changed as a result of the call |
| Exceptions |
java.lang.UnsupportedOperationException |
if the removeAll method is not supported by this collection |
java.lang.ClassCastException |
if the types of one or more elements in this collection are incompatible with the specified collection (java.util.Collection#) |
java.lang.NullPointerException |
if this collection contains one or more null elements and the specified collection does not support null elements (java.util.Collection#) or if the specified collection is null |
removeIf
open fun removeIf(filter: Predicate<in E>): Boolean
| Parameters |
filter |
Predicate<in E>: a predicate which returns true for elements to be removed |
| Return |
Boolean |
true if any elements were removed |
| Exceptions |
java.lang.NullPointerException |
if the specified filter is null |
java.lang.UnsupportedOperationException |
if elements cannot be removed from this collection. Implementations may throw this exception if a matching element cannot be removed or if, in general, removal is not supported. |
retainAll
open fun retainAll(elements: Collection<E>): Boolean
| Parameters |
c |
collection containing elements to be retained in this collection |
| Return |
Boolean |
true if this collection changed as a result of the call |
| Exceptions |
java.lang.UnsupportedOperationException |
if the retainAll operation is not supported by this collection |
java.lang.ClassCastException |
if the types of one or more elements in this collection are incompatible with the specified collection (java.util.Collection#) |
java.lang.NullPointerException |
if this collection contains one or more null elements and the specified collection does not permit null elements (java.util.Collection#) or if the specified collection is null |
take
open fun take(): E
| Return |
E |
the head of this queue |
| Exceptions |
java.lang.InterruptedException |
if interrupted while waiting |
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:
<code>String[] y = x.toArray(new String[0]);</code>
Note that
toArray(new Object[0]) is identical in function to
toArray().
| Parameters |
<T> |
the component 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 |
java.lang.ArrayStoreException |
if the runtime type of the specified array is not a supertype of the runtime type of every element in this queue |
java.lang.NullPointerException |
if the specified array is null |
toString
open fun toString(): String
| Return |
String |
a string representation of the object. |
Properties
size
open val size: Int
Returns the number of elements in this queue.
| Return |
Int |
the number of elements in this queue |
