Added in API level 9

LinkedBlockingDeque

open class LinkedBlockingDeque<E : Any!> : AbstractQueue<E>, BlockingDeque<E>, Serializable

kotlin.Any
↳	java.util.AbstractCollection<E>
	↳	java.util.AbstractQueue<E>
		↳	java.util.concurrent.LinkedBlockingDeque

An optionally-bounded blocking deque based on linked nodes.

The optional capacity bound constructor argument serves as a way to prevent excessive expansion. The capacity, if unspecified, is equal to Integer.MAX_VALUE. Linked nodes are dynamically created upon each insertion unless this would bring the deque above capacity.

Most operations run in constant time (ignoring time spent blocking). Exceptions include #remove(java.lang.Object), #removeFirstOccurrence, #removeLastOccurrence, #contains, and the bulk operations, all of which run in linear time.

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
`LinkedBlockingDeque()` Creates a `LinkedBlockingDeque` with a capacity of `Integer.MAX_VALUE`.
`LinkedBlockingDeque(capacity: Int)` Creates a `LinkedBlockingDeque` with the given (fixed) capacity.
`LinkedBlockingDeque(c: MutableCollection<out E>!)` Creates a `LinkedBlockingDeque` with a capacity of `Integer.MAX_VALUE`, initially containing the elements of the given collection, added in traversal order of the collection's iterator.

Public methods
open Boolean	`add(element: E)` Inserts the specified element at the end of this deque unless it would violate capacity restrictions.
open Boolean	`addAll(elements: Collection<E>)` Appends all of the elements in the specified collection to the end of this deque, in the order that they are returned by the specified collection's iterator.
open Unit	`addFirst(e: E)`
open Unit	`addLast(e: E)`
open Unit	`clear()` Atomically removes all of the elements from this deque.
open Boolean	`contains(element: E?)` Returns `true` if this deque contains the specified element.
open MutableIterator<E>	`descendingIterator()` Returns an iterator over the elements in this deque in reverse sequential order.
open Int	`drainTo(c: MutableCollection<in E>!)`
open Int	`drainTo(c: MutableCollection<in E>!, maxElements: Int)`
open E	`element()` Retrieves, but does not remove, the head of the queue represented by this deque.
open Unit	`forEach(action: Consumer<in E>)`
open E	`getFirst()`
open E	`getLast()`
open MutableIterator<E>	`iterator()` Returns an iterator over the elements in this deque in proper sequence.
open Boolean	`offer(e: E)` Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions.
open Boolean	`offer(e: E, timeout: Long, unit: TimeUnit!)`
open Boolean	`offerFirst(e: E)`
open Boolean	`offerFirst(e: E, timeout: Long, unit: TimeUnit!)`
open Boolean	`offerLast(e: E)`
open Boolean	`offerLast(e: E, timeout: Long, unit: TimeUnit!)`
open E?	`peek()` Retrieves, but does not remove, the head of this queue, or returns `null` if this queue is empty.
open E?	`peekFirst()` Retrieves, but does not remove, the first element of this deque, or returns `null` if this deque is empty.
open E?	`peekLast()` Retrieves, but does not remove, the last element of this deque, or returns `null` if this deque is empty.
open E?	`poll()` Retrieves and removes the head of this queue, or returns `null` if this queue is empty.
open E	`poll(timeout: Long, unit: TimeUnit!)` Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), waiting up to the specified wait time if necessary for an element to become available.
open E?	`pollFirst()` Retrieves and removes the first element of this deque, or returns `null` if this deque is empty.
open E	`pollFirst(timeout: Long, unit: TimeUnit!)` Retrieves and removes the first element of this deque, waiting up to the specified wait time if necessary for an element to become available.
open E?	`pollLast()` Retrieves and removes the last element of this deque, or returns `null` if this deque is empty.
open E	`pollLast(timeout: Long, unit: TimeUnit!)` Retrieves and removes the last element of this deque, waiting up to the specified wait time if necessary for an element to become available.
open E	`pop()`
open Unit	`push(e: E)`
open Unit	`put(e: E)`
open Unit	`putFirst(e: E)`
open Unit	`putLast(e: E)`
open Int	`remainingCapacity()` Returns the number of additional elements that this deque can ideally (in the absence of memory or resource constraints) accept without blocking.
open E	`remove()` Retrieves and removes the head of the queue represented by this deque.
open Boolean	`remove(element: E?)` Removes the first occurrence of the specified element from this deque.
open Boolean	`removeAll(elements: Collection<E>)`
open E	`removeFirst()`
open Boolean	`removeFirstOccurrence(o: Any?)` Removes the first occurrence of the specified element from this deque.
open Boolean	`removeIf(filter: Predicate<in E>)`
open E	`removeLast()`
open Boolean	`removeLastOccurrence(o: Any?)` Removes the last occurrence of the specified element from this deque.
open Boolean	`retainAll(elements: Collection<E>)`
open Spliterator<E>	`spliterator()` Returns a `Spliterator` over the elements in this deque.
open E	`take()` Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), waiting if necessary until an element becomes available.
open E	`takeFirst()` Retrieves and removes the first element of this deque, waiting if necessary until an element becomes available.
open E	`takeLast()` Retrieves and removes the last element of this deque, waiting if necessary until an element becomes available.
open Array<Any!>	`toArray()` Returns an array containing all of the elements in this deque, in proper sequence (from first to last element).
open Array<T>	`toArray(a: Array<T>)` Returns an array containing all of the elements in this deque, in proper sequence; the runtime type of the returned array is that of the specified array.
open String	`toString()` Returns a string representation of this collection.

Properties
open Int	`size` Returns the number of elements in this deque.

Public constructors

LinkedBlockingDeque

Added in API level 9

LinkedBlockingDeque()

Creates a LinkedBlockingDeque with a capacity of Integer.MAX_VALUE.

LinkedBlockingDeque

Added in API level 9

LinkedBlockingDeque(capacity: Int)

Creates a LinkedBlockingDeque with the given (fixed) capacity.

Parameters
`capacity`	Int: the capacity of this deque

Exceptions
`java.lang.IllegalArgumentException`	if `capacity` is less than 1

LinkedBlockingDeque

Added in API level 9

LinkedBlockingDeque(c: MutableCollection<out E>!)

Creates a LinkedBlockingDeque with a capacity of Integer.MAX_VALUE, initially containing the elements of the given collection, added in traversal order of the collection's iterator.

Parameters
`c`	MutableCollection<out E>!: the collection of elements to initially contain

Exceptions
`java.lang.NullPointerException`	if the specified collection or any of its elements are null

Public methods

add

Added in API level 9

open fun add(element: E): Boolean

Inserts the specified element at the end of this deque unless it would violate capacity restrictions. When using a capacity-restricted deque, it is generally preferable to use method #offer(java.lang.Object).

This method is equivalent to #addLast.

Parameters
`e`	the element to add

Return
`Boolean`	`true` (as specified by `Collection.add`)

Exceptions
`java.lang.ClassCastException`	if the class of the specified element prevents it from being added to this deque
`java.lang.IllegalArgumentException`	if some property of the specified element prevents it from being added to this deque
`java.lang.IllegalStateException`	if this deque is full
`java.lang.NullPointerException`	if the specified element is null
`java.lang.UnsupportedOperationException`	if the `add` operation is not supported by this collection

addAll

Added in API level 9

open fun addAll(elements: Collection<E>): Boolean

Appends all of the elements in the specified collection to the end of this deque, in the order that they are returned by the specified collection's iterator. Attempts to addAll of a deque to itself result in IllegalArgumentException.

Parameters
`c`	the elements to be inserted into this deque

Return
`Boolean`	`true` if this deque changed as a result of the call

Exceptions
`java.lang.ClassCastException`	if the class of an element of the specified collection prevents it from being added to this deque
`java.lang.IllegalArgumentException`	if the collection is this deque
`java.lang.IllegalStateException`	if this deque is full
`java.lang.NullPointerException`	if the specified collection or any of its elements are null
`java.lang.UnsupportedOperationException`	if the `addAll` operation is not supported by this collection

See Also

addFirst

Added in API level 9

open fun addFirst(e: E): Unit

Parameters
`e`	E: the element to add

Exceptions
`java.lang.NullPointerException`	if the specified element is null
`java.lang.UnsupportedOperationException`	if this collection implementation does not support this operation
`java.lang.ClassCastException`	if the class of the specified element prevents it from being added to this deque
`java.lang.IllegalArgumentException`	if some property of the specified element prevents it from being added to this deque
`java.lang.IllegalStateException`	if this deque is full

addLast

Added in API level 9

open fun addLast(e: E): Unit

Parameters
`e`	E: the element to add

Exceptions
`java.lang.NullPointerException`	if the specified element is null
`java.lang.UnsupportedOperationException`	if this collection implementation does not support this operation
`java.lang.ClassCastException`	if the class of the specified element prevents it from being added to this deque
`java.lang.IllegalArgumentException`	if some property of the specified element prevents it from being added to this deque
`java.lang.IllegalStateException`	if this deque is full

clear

Added in API level 9

open fun clear(): Unit

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

Exceptions
`java.lang.UnsupportedOperationException`	if the `clear` operation is not supported by this collection

contains

Added in API level 9

open fun contains(element: E?): Boolean

Returns true if this deque contains the specified element. More formally, returns true if and only if this deque contains at least one element e such that o.equals(e).

Parameters
`o`	object to be checked for containment in this deque

Return
`Boolean`	`true` if this deque contains the specified element

Exceptions
`java.lang.ClassCastException`	if the class of the specified element is incompatible with this deque (optional)
`java.lang.NullPointerException`	if the specified element is null (optional)

descendingIterator

Added in API level 9

open fun descendingIterator(): MutableIterator<E>

Returns an iterator over the elements in this deque in reverse sequential order. The elements will be returned in order from last (tail) to first (head).

The returned iterator is weakly consistent.

Return
`MutableIterator<E>`	an iterator over the elements in this deque in reverse order

drainTo

Added in API level 9

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
`java.lang.ClassCastException`	if the class of an element of this queue prevents it from being added to the specified collection
`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
`java.lang.NullPointerException`	if the specified collection is null
`java.lang.UnsupportedOperationException`	if addition of elements is not supported by the specified collection

drainTo

Added in API level 9

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.ClassCastException`	if the class of an element of this queue prevents it from being added to the specified collection
`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
`java.lang.NullPointerException`	if the specified collection is null
`java.lang.UnsupportedOperationException`	if addition of elements is not supported by the specified collection

element

Added in API level 9

open fun element(): E

Retrieves, but does not remove, the head of the queue represented by this deque. This method differs from #peek() only in that it throws an exception if this deque is empty.

This method is equivalent to #getFirst().

Return
`E`	the head of the queue represented by this deque

Exceptions
`java.util.NoSuchElementException`	if this deque is empty

forEach

Added in API level 24

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

getFirst

Added in API level 9

open fun getFirst(): E

Return
`E`	the head of this deque

Exceptions
`java.util.NoSuchElementException`	if this deque is empty

getLast

Added in API level 9

open fun getLast(): E

Return
`E`	the tail of this deque

Exceptions
`java.util.NoSuchElementException`	if this deque is empty

iterator

Added in API level 9

open fun iterator(): MutableIterator<E>

Returns an iterator over the elements in this deque 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 deque in proper sequence

offer

Added in API level 9

open fun offer(e: E): Boolean

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.

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 deque
`java.lang.IllegalArgumentException`	if some property of the specified element prevents it from being added to this deque
`java.lang.NullPointerException`	if the specified element is null

offer

Added in API level 9

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

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 the element was added to this deque, else `false`

Exceptions
`java.lang.ClassCastException`	if the class of the specified element prevents it from being added to this deque
`java.lang.IllegalArgumentException`	if some property of the specified element prevents it from being added to this deque
`java.lang.InterruptedException`	if interrupted while waiting
`java.lang.NullPointerException`	if the specified element is null

offerFirst

Added in API level 9

open fun offerFirst(e: E): Boolean

Parameters
`e`	E: the element to add

Return
`Boolean`	`true` if the element was added to this deque, else `false`

Exceptions
`java.lang.ClassCastException`	if the class of the specified element prevents it from being added to this deque
`java.lang.IllegalArgumentException`	if some property of the specified element prevents it from being added to this deque
`java.lang.NullPointerException`	if the specified element is null

offerFirst

Added in API level 9

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

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.ClassCastException`	if the class of the specified element prevents it from being added to this deque
`java.lang.IllegalArgumentException`	if some property of the specified element prevents it from being added to this deque
`java.lang.InterruptedException`	if interrupted while waiting
`java.lang.NullPointerException`	if the specified element is null

offerLast

Added in API level 9

open fun offerLast(e: E): Boolean

Parameters
`e`	E: the element to add

Return
`Boolean`	`true` if the element was added to this deque, else `false`

Exceptions
`java.lang.ClassCastException`	if the class of the specified element prevents it from being added to this deque
`java.lang.IllegalArgumentException`	if some property of the specified element prevents it from being added to this deque
`java.lang.NullPointerException`	if the specified element is null

offerLast

Added in API level 9

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

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.ClassCastException`	if the class of the specified element prevents it from being added to this deque
`java.lang.IllegalArgumentException`	if some property of the specified element prevents it from being added to this deque
`java.lang.InterruptedException`	if interrupted while waiting
`java.lang.NullPointerException`	if the specified element is null

peek

Added in API level 9

open fun peek(): E?

Retrieves, but does not remove, the head of this queue, or returns null if this queue is empty.

Return
`E?`	the head of this queue, or `null` if this queue is empty

peekFirst

Added in API level 9

open fun peekFirst(): E?

Retrieves, but does not remove, the first element of this deque, or returns null if this deque is empty.

Return
`E?`	the head of this deque, or `null` if this deque is empty

peekLast

Added in API level 9

open fun peekLast(): E?

Retrieves, but does not remove, the last element of this deque, or returns null if this deque is empty.

Return
`E?`	the tail of this deque, or `null` if this deque is empty

poll

Added in API level 9

open fun poll(): E?

Retrieves and removes the head of this queue, or returns null if this queue is empty.

Return
`E?`	the head of this queue, or `null` if this queue is empty

poll

Added in API level 9

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

Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), waiting up to the specified wait time if necessary for an element to become available.

This method is equivalent to pollFirst.

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 deque, or `null` if the specified waiting time elapses before an element is available

Exceptions
`java.lang.InterruptedException`	if interrupted while waiting

pollFirst

Added in API level 9

open fun pollFirst(): E?

Retrieves and removes the first element of this deque, or returns null if this deque is empty.

Return
`E?`	the head of this deque, or `null` if this deque is empty

pollFirst

Added in API level 9

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

Retrieves and removes the first element of this deque, waiting up to the specified wait time if necessary for an element to become available.

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 deque, or `null` if the specified waiting time elapses before an element is available

Exceptions
`java.lang.InterruptedException`	if interrupted while waiting

pollLast

Added in API level 9

open fun pollLast(): E?

Retrieves and removes the last element of this deque, or returns null if this deque is empty.

Return
`E?`	the tail of this deque, or `null` if this deque is empty

pollLast

Added in API level 9

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

Retrieves and removes the last element of this deque, waiting up to the specified wait time if necessary for an element to become available.

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 tail of this deque, or `null` if the specified waiting time elapses before an element is available

Exceptions
`java.lang.InterruptedException`	if interrupted while waiting

pop

Added in API level 9

open fun pop(): E

Return
`E`	the element at the front of this deque (which is the top of the stack represented by this deque)

Exceptions
`java.util.NoSuchElementException`	if this deque is empty

push

Added in API level 9

open fun push(e: E): Unit

Parameters
`e`	E: the element to push

Exceptions
`java.lang.ClassCastException`	if the class of the specified element prevents it from being added to this deque
`java.lang.IllegalArgumentException`	if some property of the specified element prevents it from being added to this deque
`java.lang.IllegalStateException`	if this deque is full
`java.lang.NullPointerException`	if the specified element is null

put

Added in API level 9

open fun put(e: E): Unit

Parameters
`e`	E: the element to add

Exceptions
`java.lang.ClassCastException`	if the class of the specified element prevents it from being added to this deque
`java.lang.IllegalArgumentException`	if some property of the specified element prevents it from being added to this deque
`java.lang.InterruptedException`	if interrupted while waiting
`java.lang.NullPointerException`	if the specified element is null

putFirst

Added in API level 9

open fun putFirst(e: E): Unit

Parameters
`e`	E: the element to add

Exceptions
`java.lang.ClassCastException`	if the class of the specified element prevents it from being added to this deque
`java.lang.IllegalArgumentException`	if some property of the specified element prevents it from being added to this deque
`java.lang.InterruptedException`	if interrupted while waiting
`java.lang.NullPointerException`	if the specified element is null

putLast

Added in API level 9

open fun putLast(e: E): Unit

Parameters
`e`	E: the element to add

Exceptions
`java.lang.ClassCastException`	if the class of the specified element prevents it from being added to this deque
`java.lang.IllegalArgumentException`	if some property of the specified element prevents it from being added to this deque
`java.lang.InterruptedException`	if interrupted while waiting
`java.lang.NullPointerException`	if the specified element is null

remainingCapacity

Added in API level 9

open fun remainingCapacity(): Int

Returns the number of additional elements that this deque can ideally (in the absence of memory or resource constraints) accept without blocking. This is always equal to the initial capacity of this deque les