Java compact1, compact2, compact3 java.util.concurrent Class LinkedBlockingDeque<E>（JDK8）

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Java™ Platform
Standard Ed. 8

All Classes

Summary:
Nested |
Field |
Constr |
Method

Detail:
Field |
Constr |
Method

java.lang.Object
- java.util.AbstractCollection<E>
- - java.util.AbstractQueue<E>
  - - java.util.concurrent.LinkedBlockingDeque<E>

Type Parameters:

E - the type of elements held in this collection

All Implemented Interfaces:

Serializable, Iterable<E>, Collection<E>, BlockingDeque<E>, BlockingQueue<E>, Deque<E>, Queue<E>
```
public class LinkedBlockingDeque<E>
extends AbstractQueue<E>
implements BlockingDeque<E>, Serializable
```
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, removeFirstOccurrence, removeLastOccurrence, contains, iterator.remove(), 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.

Since:

1.6

See Also:

Serialized Form

Constructor Summary

Constructors
Constructor and Description
`LinkedBlockingDeque()` Creates a `LinkedBlockingDeque` with a capacity of `Integer.MAX_VALUE`.
`LinkedBlockingDeque(Collection<? extends E> c)` 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.
`LinkedBlockingDeque(int capacity)` Creates a `LinkedBlockingDeque` with the given (fixed) capacity.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`add(E e)` Inserts the specified element at the end of this deque unless it would violate capacity restrictions.
`void`	`addFirst(E e)` Inserts the specified element at the front of this deque if it is possible to do so immediately without violating capacity restrictions, throwing an `IllegalStateException` if no space is currently available.
`void`	`addLast(E e)` Inserts the specified element at the end of this deque if it is possible to do so immediately without violating capacity restrictions, throwing an `IllegalStateException` if no space is currently available.
`void`	`clear()` Atomically removes all of the elements from this deque.
`boolean`	`contains(Object o)` Returns `true` if this deque contains the specified element.
`Iterator<E>`	`descendingIterator()` Returns an iterator over the elements in this deque in reverse sequential order.
`int`	`drainTo(Collection<? super E> c)` Removes all available elements from this queue and adds them to the given collection.
`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.
`E`	`element()` Retrieves, but does not remove, the head of the queue represented by this deque.
`E`	`getFirst()` Retrieves, but does not remove, the first element of this deque.
`E`	`getLast()` Retrieves, but does not remove, the last element of this deque.
`Iterator<E>`	`iterator()` Returns an iterator over the elements in this deque in proper sequence.
`boolean`	`offer(E e)` Inserts the specified element into the queue represented by this deque (in other words, at the tail of this deque) if it is possible to do so immediately without violating capacity restrictions, returning `true` upon success and `false` if no space is currently available.
`boolean`	`offer(E e, long timeout, TimeUnit unit)` Inserts the specified element into the queue represented by this deque (in other words, at the tail of this deque), waiting up to the specified wait time if necessary for space to become available.
`boolean`	`offerFirst(E e)` Inserts the specified element at the front of this deque if it is possible to do so immediately without violating capacity restrictions, returning `true` upon success and `false` if no space is currently available.
`boolean`	`offerFirst(E e, long timeout, TimeUnit unit)` Inserts the specified element at the front of this deque, waiting up to the specified wait time if necessary for space to become available.
`boolean`	`offerLast(E e)` Inserts the specified element at the end of this deque if it is possible to do so immediately without violating capacity restrictions, returning `true` upon success and `false` if no space is currently available.
`boolean`	`offerLast(E e, long timeout, TimeUnit unit)` Inserts the specified element at the end of this deque, waiting up to the specified wait time if necessary for space to become available.
`E`	`peek()` Retrieves, but does not remove, the head of the queue represented by this deque (in other words, the first element of this deque), or returns `null` if this deque is empty.
`E`	`peekFirst()` Retrieves, but does not remove, the first element of this deque, or returns `null` if this deque is empty.
`E`	`peekLast()` Retrieves, but does not remove, the last element of this deque, or returns `null` if this deque is empty.
`E`	`poll()` Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), or returns `null` if this deque is empty.
`E`	`poll(long timeout, TimeUnit unit)` 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.
`E`	`pollFirst()` Retrieves and removes the first element of this deque, or returns `null` if this deque is empty.
`E`	`pollFirst(long timeout, TimeUnit unit)` Retrieves and removes the first element of this deque, waiting up to the specified wait time if necessary for an element to become available.
`E`	`pollLast()` Retrieves and removes the last element of this deque, or returns `null` if this deque is empty.
`E`	`pollLast(long timeout, TimeUnit unit)` Retrieves and removes the last element of this deque, waiting up to the specified wait time if necessary for an element to become available.
`E`	`pop()` Pops an element from the stack represented by this deque.
`void`	`push(E e)` Pushes an element onto the stack represented by this deque (in other words, at the head of this deque) if it is possible to do so immediately without violating capacity restrictions, throwing an `IllegalStateException` if no space is currently available.
`void`	`put(E e)` Inserts the specified element into the queue represented by this deque (in other words, at the tail of this deque), waiting if necessary for space to become available.
`void`	`putFirst(E e)` Inserts the specified element at the front of this deque, waiting if necessary for space to become available.
`void`	`putLast(E e)` Inserts the specified element at the end of this deque, waiting if necessary for space to become available.
`int`	`remainingCapacity()` Returns the number of additional elements that this deque can ideally (in the absence of memory or resource constraints) accept without blocking.
`E`	`remove()` Retrieves and removes the head of the queue represented by this deque.
`boolean`	`remove(Object o)` Removes the first occurrence of the specified element from this deque.
`E`	`removeFirst()` Retrieves and removes the first element of this deque.
`boolean`	`removeFirstOccurrence(Object o)` Removes the first occurrence of the specified element from this deque.
`E`	`removeLast()` Retrieves and removes the last element of this deque.
`boolean`	`removeLastOccurrence(Object o)` Removes the last occurrence of the specified element from this deque.
`int`	`size()` Returns the number of elements in this deque.
`Spliterator<E>`	`spliterator()` Returns a `Spliterator` over the elements in this deque.
`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.
`E`	`takeFirst()` Retrieves and removes the first element of this deque, waiting if necessary until an element becomes available.
`E`	`takeLast()` Retrieves and removes the last element of this deque, waiting if necessary until an element becomes available.
`Object[]`	`toArray()` Returns an array containing all of the elements in this deque, in proper sequence (from first to last element).
`<T> T[]`	`toArray(T[] a)` 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.
`String`	`toString()` Returns a string representation of this collection.

Methods inherited from class java.util.AbstractQueue
addAll

Methods inherited from class java.util.AbstractCollection
containsAll, isEmpty, removeAll, retainAll

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Collection
addAll, containsAll, equals, hashCode, isEmpty, parallelStream, removeAll, removeIf, retainAll, stream

Methods inherited from interface java.lang.Iterable
forEach

- Constructor Detail
  - LinkedBlockingDeque
```
public LinkedBlockingDeque()
```
    Creates a LinkedBlockingDeque with a capacity of Integer.MAX_VALUE.
  - LinkedBlockingDeque
```
public LinkedBlockingDeque(int capacity)
```
    Creates a LinkedBlockingDeque with the given (fixed) capacity.
    
    Parameters:
    
    capacity - the capacity of this deque
    
    Throws:
    
    IllegalArgumentException - if capacity is less than 1
  - LinkedBlockingDeque
```
public LinkedBlockingDeque(Collection<? extends E> c)
```
    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 - the collection of elements to initially contain
    
    Throws:
    
    NullPointerException - if the specified collection or any of its elements are null
- Method Detail
  - addFirst
```
public void addFirst(E e)
```
    Description copied from interface: BlockingDeque
    
    Inserts the specified element at the front of this deque if it is possible to do so immediately without violating capacity restrictions, throwing an IllegalStateException if no space is currently available. When using a capacity-restricted deque, it is generally preferable to use offerFirst.
    
    Specified by:
    
    addFirst in interface BlockingDeque<E>
    
    Specified by:
    
    addFirst in interface Deque<E>
    
    Parameters:
    
    e - the element to add
    
    Throws:
    
    IllegalStateException - if this deque is full
    
    NullPointerException - if the specified element is null
  - addLast
```
public void addLast(E e)
```
    Description copied from interface: BlockingDeque
    
    Inserts the specified element at the end of this deque if it is possible to do so immediately without violating capacity restrictions, throwing an IllegalStateException if no space is currently available. When using a capacity-restricted deque, it is generally preferable to use offerLast.
    
    Specified by:
    
    addLast in interface BlockingDeque<E>
    
    Specified by:
    
    addLast in interface Deque<E>
    
    Parameters:
    
    e - the element to add
    
    Throws:
    
    IllegalStateException - if this deque is full
    
    NullPointerException - if the specified element is null
  - offerFirst
```
public boolean offerFirst(E e)
```
    Description copied from interface: BlockingDeque
    
    Inserts the specified element at the front of this deque if it is possible to do so immediately without violating capacity restrictions, returning true upon success and false if no space is currently available. When using a capacity-restricted deque, this method is generally preferable to the addFirst method, which can fail to insert an element only by throwing an exception.
    
    Specified by:
    
    offerFirst in interface BlockingDeque<E>
    
    Specified by:
    
    offerFirst in interface Deque<E>
    
    Parameters:
    
    e - the element to add
    
    Returns:
    
    true if the element was added to this deque, else false
    
    Throws:
    
    NullPointerException - if the specified element is null
  - offerLast
```
public boolean offerLast(E e)
```
    Description copied from interface: BlockingDeque
    
    Inserts the specified element at the end of this deque if it is possible to do so immediately without violating capacity restrictions, returning true upon success and false if no space is currently available. When using a capacity-restricted deque, this method is generally preferable to the addLast method, which can fail to insert an element only by throwing an exception.
    
    Specified by:
    
    offerLast in interface BlockingDeque<E>
    
    Specified by:
    
    offerLast in interface Deque<E>
    
    Parameters:
    
    e - the element to add
    
    Returns:
    
    true if the element was added to this deque, else false
    
    Throws:
    
    NullPointerException - if the specified element is null
  - putFirst
```
public void putFirst(E e)
              throws InterruptedException
```
    Description copied from interface: BlockingDeque
    
    Inserts the specified element at the front of this deque, waiting if necessary for space to become available.
    
    Specified by:
    
    putFirst in interface BlockingDeque<E>
    
    Parameters:
    
    e - the element to add
    
    Throws:
    
    NullPointerException - if the specified element is null
    
    InterruptedException - if interrupted while waiting
  - putLast
```
public void putLast(E e)
             throws InterruptedException
```
    Description copied from interface: BlockingDeque
    
    Inserts the specified element at the end of this deque, waiting if necessary for space to become available.
    
    Specified by:
    
    putLast in interface BlockingDeque<E>
    
    Parameters:
    
    e - the element to add
    
    Throws:
    
    NullPointerException - if the specified element is null
    
    InterruptedException - if interrupted while waiting
  - offerFirst
```
public boolean offerFirst(E e,
                          long timeout,
                          TimeUnit unit)
                   throws InterruptedException
```
    Description copied from interface: BlockingDeque
    
    Inserts the specified element at the front of this deque, waiting up to the specified wait time if necessary for space to become available.
    
    Specified by:
    
    offerFirst in interface BlockingDeque<E>
    
    Parameters:
    
    e - the element to add
    
    timeout - how long to wait before giving up, in units of unit
    
    unit - a TimeUnit determining how to interpret the timeout parameter
    
    Returns:
    
    true if successful, or false if the specified waiting time elapses before space is available
    
    Throws:
    
    NullPointerException - if the specified element is null
    
    InterruptedException - if interrupted while waiting
  - offerLast
```
public boolean offerLast(E e,
                         long timeout,
                         TimeUnit unit)
                  throws InterruptedException
```
    Description copied from interface: BlockingDeque
    
    Inserts the specified element at the end of this deque, waiting up to the specified wait time if necessary for space to become available.
    
    Specified by:
    
    offerLast in interface BlockingDeque<E>
    
    Parameters:
    
    e - the element to add
    
    timeout - how long to wait before giving up, in units of unit
    
    unit - a TimeUnit determining how to interpret the timeout parameter
    
    Returns:
    
    true if successful, or false if the specified waiting time elapses before space is available
    
    Throws:
    
    NullPointerException - if the specified element is null
    
    InterruptedException - if interrupted while waiting
  - removeFirst
```
public E removeFirst()
```
    Description copied from interface: Deque
    
    Retrieves and removes the first element of this deque. This method differs from pollFirst only in that it throws an exception if this deque is empty.
    
    Specified by:
    
    removeFirst in interface Deque<E>
    
    Returns:
    
    the head of this deque
    
    Throws:
    
    NoSuchElementException - if this deque is empty
  - removeLast
```
public E removeLast()
```
    Description copied from interface: Deque
    
    Retrieves and removes the last element of this deque. This method differs from pollLast only in that it throws an exception if this deque is empty.
    
    Specified by:
    
    removeLast in interface Deque<E>
    
    Returns:
    
    the tail of this deque
    
    Throws:
    
    NoSuchElementException - if this deque is empty
  - pollFirst
```
public E pollFirst()
```
    Description copied from interface: Deque
    
    Retrieves and removes the first element of this deque, or returns null if this deque is empty.
    
    Specified by:
    
    pollFirst in interface Deque<E>
    
    Returns:
    
    the head of this deque, or null if this deque is empty
  - pollLast
```
public E pollLast()
```
    Description copied from interface: Deque
    
    Retrieves and removes the last element of this deque, or returns null if this deque is empty.
    
    Specified by:
    
    pollLast in interface Deque<E>
    
    Returns:
    
    the tail of this deque, or null if this deque is empty
  - takeFirst
```
public E takeFirst()
            throws InterruptedException
```
    Description copied from interface: BlockingDeque
    
    Retrieves and removes the first element of this deque, waiting if necessary until an element becomes available.
    
    Specified by:
    
    takeFirst in interface BlockingDeque<E>
    
    Returns:
    
    the head of this deque
    
    Throws:
    
    InterruptedException - if interrupted while waiting
  - takeLast
```
public E takeLast()
           throws InterruptedException
```
    Description copied from interface: BlockingDeque
    
    Retrieves and removes the last element of this deque, waiting if necessary until an element becomes available.
    
    Specified by:
    
    takeLast in interface BlockingDeque<E>
    
    Returns:
    
    the tail of this deque
    
    Throws:
    
    InterruptedException - if interrupted while waiting
  - pollFirst
```
public E pollFirst(long timeout,
                   TimeUnit unit)
            throws InterruptedException
```
    Description copied from interface: BlockingDeque
    
    Retrieves and removes the first element of this deque, waiting up to the specified wait time if necessary for an element to become available.
    
    Specified by:
    
    pollFirst in interface BlockingDeque<E>
    
    Parameters:
    
    timeout - how long to wait before giving up, in units of unit
    
    unit - a TimeUnit determining how to interpret the timeout parameter
    
    Returns:
    
    the head of this deque, or null if the specified waiting time elapses before an element is available
    
    Throws:
    
    InterruptedException - if interrupted while waiting
  - pollLast
```
public E pollLast(long timeout,
                  TimeUnit unit)
           throws InterruptedException
```
    Description copied from interface: BlockingDeque
    
    Retrieves and removes the last element of this deque, waiting up to the specified wait time if necessary for an element to become available.
    
    Specified by:
    
    pollLast in interface BlockingDeque<E>
    
    Parameters:
    
    timeout - how long to wait before giving up, in units of unit
    
    unit - a TimeUnit determining how to interpret the timeout parameter
    
    Returns:
    
    the tail of this deque, or null if the specified waiting time elapses before an element is available
    
    Throws:
    
    InterruptedException - if interrupted while waiting
  - getFirst
```
public E getFirst()
```
    Description copied from interface: Deque
    
    Retrieves, but does not remove, the first element of this deque. This method differs from peekFirst only in that it throws an exception if this deque is empty.
    
    Specified by:
    
    getFirst in interface Deque<E>
    
    Returns:
    
    the head of this deque
    
    Throws:
    
    NoSuchElementException - if this deque is empty
  - getLast
```
public E getLast()
```
    Description copied from interface: Deque
    
    Retrieves, but does not remove, the last element of this deque. This method differs from peekLast only in that it throws an exception if this deque is empty.
    
    Specified by:
    
    getLast in interface Deque<E>
    
    Returns:
    
    the tail of this deque
    
    Throws:
    
    NoSuchElementException - if this deque is empty
  - peekFirst
```
public E peekFirst()
```
    Description copied from interface: Deque
    
    Retrieves, but does not remove, the first element of this deque, or returns null if this deque is empty.
    
    Specified by:
    
    peekFirst in interface Deque<E>
    
    Returns:
    
    the head of this deque, or null if this deque is empty
  - peekLast
```
public E peekLast()
```
    Description copied from interface: Deque
    
    Retrieves, but does not remove, the last element of this deque, or returns null if this deque is empty.
    
    Specified by:
    
    peekLast in interface Deque<E>
    
    Returns:
    
    the tail of this deque, or null if this deque is empty
  - removeFirstOccurrence
```
public boolean removeFirstOccurrence(Object o)
```
    Description copied from interface: BlockingDeque
    
    Removes the first occurrence of the specified element from this deque. If the deque does not contain the element, it is unchanged. More formally, removes the first element e such that o.equals(e) (if such an element exists). Returns true if this deque contained the specified element (or equivalently, if this deque changed as a result of the call).
    
    Specified by:
    
    removeFirstOccurrence in interface BlockingDeque<E>
    
    Specified by:
    
    removeFirstOccurrence in interface Deque<E>
    
    Parameters:
    
    o - element to be removed from this deque, if present
    
    Returns:
    
    true if an element was removed as a result of this call
  - removeLastOccurrence
```
public boolean removeLastOccurrence(Object o)
```
    Description copied from interface: BlockingDeque
    
    Removes the last occurrence of the specified element from this deque. If the deque does not contain the element, it is unchanged. More formally, removes the last element e such that o.equals(e) (if such an element exists). Returns true if this deque contained the specified element (or equivalently, if this deque changed as a result of the call).
    
    Specified by:
    
    removeLastOccurrence in interface BlockingDeque<E>
    
    Specified by:
    
    removeLastOccurrence in interface Deque<E>
    
    Parameters:
    
    o - element to be removed from this deque, if present
    
    Returns:
    
    true if an element was removed as a result of this call
  - add
```
public boolean add(E e)
```
    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.
    This method is equivalent to addLast(E).
    
    Specified by:
    
    add in interface Collection<E>
    
    Specified by:
    
    add in interface BlockingDeque<E>
    
    Specified by:
    
    add in interface BlockingQueue<E>
    
    Specified by:
    
    add in interface Deque<E>
    
    Specified by:
    
    add in interface Queue<E>
    
    Overrides:
    
    add in class AbstractQueue<E>
    
    Parameters:
    
    e - the element to add
    
    Returns:
    
    true (as specified by Collection.add(E))
    
    Throws:
    
    IllegalStateException - if this deque is full
    
    NullPointerException - if the specified element is null
  - offer
```
public boolean offer(E e)
```
    Description copied from interface: BlockingDeque
    
    Inserts the specified element into the queue represented by this deque (in other words, at the tail of this deque) if it is possible to do so immediately without violating capacity restrictions, returning true upon success and false if no space is currently available. When using a capacity-restricted deque, this method is generally preferable to the BlockingDeque.add(E) method, which can fail to insert an element only by throwing an exception.
    This method is equivalent to offerLast.
    
    Specified by:
    
    offer in interface BlockingDeque<E>
    
    Specified by:
    
    offer in interface BlockingQueue<E>
    
    Specified by:
    
    offer in interface Deque<E>
    
    Specified by:
    
    offer in interface Queue<E>
    
    Parameters:
    
    e - the element to add
    
    Returns:
    
    true if the element was added to this queue, else false
    
    Throws:
    
    NullPointerException - if the specified element is null
  - put
```
public void put(E e)
         throws InterruptedException
```
    Description copied from interface: BlockingDeque
    
    Inserts the specified element into the queue represented by this deque (in other words, at the tail of this deque), waiting if necessary for space to become available.
    This method is equivalent to putLast.
    
    Specified by:
    
    put in interface BlockingDeque<E>
    
    Specified by:
    
    put in interface BlockingQueue<E>
    
    Parameters:
    
    e - the element to add
    
    Throws:
    
    NullPointerException - if the specified element is null
    
    InterruptedException - if interrupted while waiting
  - offer
```
public boolean offer(E e,
                     long timeout,
                     TimeUnit unit)
              throws InterruptedException
```
    Description copied from interface: BlockingDeque
    
    Inserts the specified element into the queue represented by this deque (in other words, at the tail of this deque), waiting up to the specified wait time if necessary for space to become available.
    This method is equivalent to offerLast.
    
    Specified by:
    
    offer in interface BlockingDeque<E>
    
    Specified by:
    
    offer in interface BlockingQueue<E>
    
    Parameters:
    
    e - the element to add
    
    timeout - how long to wait before giving up, in units of unit
    
    unit - a TimeUnit determining how to interpret the timeout parameter
    
    Returns:
    
    true if the element was added to this deque, else false
    
    Throws:
    
    NullPointerException - if the specified element is null
    
    InterruptedException - if interrupted while waiting
  - remove
```
public E remove()
```
    Retrieves and removes the head of the queue represented by this deque. This method differs from poll only in that it throws an exception if this deque is empty.
    This method is equivalent to removeFirst.
    
    Specified by:
    
    remove in interface BlockingDeque<E>
    
    Specified by:
    
    remove in interface Deque<E>
    
    Specified by:
    
    remove in interface Queue<E>
    
    Overrides:
    
    remove in class AbstractQueue<E>
    
    Returns:
    
    the head of the queue represented by this deque
    
    Throws:
    
    NoSuchElementException - if this deque is empty
  - poll
```
public E poll()
```
    Description copied from interface: BlockingDeque
    
    Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), or returns null if this deque is empty.
    This method is equivalent to Deque.pollFirst().
    
    Specified by:
    
    poll in interface BlockingDeque<E>
    
    Specified by:
    
    poll in interface Deque<E>
    
    Specified by:
    
    poll in interface Queue<E>
    
    Returns:
    
    the head of this deque, or null if this deque is empty
  - take
```
public E take()
       throws InterruptedException
```
    Description copied from interface: BlockingDeque
    
    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.
    This method is equivalent to takeFirst.
    
    Specified by:
    
    take in interface BlockingDeque<E>
    
    Specified by:
    
    take in interface BlockingQueue<E>
    
    Returns:
    
    the head of this deque
    
    Throws:
    
    InterruptedException - if interrupted while waiting
  - poll
```
public E poll(long timeout,
              TimeUnit unit)
       throws InterruptedException
```
    Description copied from interface: BlockingDeque
    
    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.
    
    Specified by:
    
    poll in interface BlockingDeque<E>
    
    Specified by:
    
    poll in interface BlockingQueue<E>
    
    Parameters:
    
    timeout - how long to wait before giving up, in units of unit
    
    unit - a TimeUnit determining how to interpret the timeout parameter
    
    Returns:
    
    the head of this deque, or null if the specified waiting time elapses before an element is available
    
    Throws:
    
    InterruptedException - if interrupted while waiting
  - element
```
public E element()
```
    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.
    
    Specified by:
    
    element in interface BlockingDeque<E>
    
    Specified by:
    
    element in interface Deque<E>
    
    Specified by:
    
    element in interface Queue<E>
    
    Overrides:
    
    element in class AbstractQueue<E>
    
    Returns:
    
    the head of the queue represented by this deque
    
    Throws:
    
    NoSuchElementException - if this deque is empty
  - peek
```
public E peek()
```
    Description copied from interface: BlockingDeque
    
    Retrieves, but does not remove, the head of the queue represented by this deque (in other words, the first element of this deque), or returns null if this deque is empty.
    This method is equivalent to peekFirst.
    
    Specified by:
    
    peek in interface BlockingDeque<E>
    
    Specified by:
    
    peek in interface Deque<E>
    
    Specified by:
    
    peek in interface Queue<E>
    
    Returns:
    
    the head of this deque, or null if this deque is empty
  - remainingCapacity
```
public int remainingCapacity()
```
    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 less the current size of this deque.
    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.
    
    Specified by:
    
    remainingCapacity in interface BlockingQueue<E>
    
    Returns:
    
    the remaining capacity
  - drainTo
```
public int drainTo(Collection<? super E> c)
```
    Description copied from interface: BlockingQueue
    
    Removes all available elements from this queue and adds them to the given collection. This operation may be more efficient than repeatedly polling this queue. A failure encountered while attempting to add elements to collection c may result in elements being in neither, either or both collections when the associated exception is thrown. Attempts to drain 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.
    
    Specified by:
    
    drainTo in interface BlockingQueue<E>
    
    Parameters:
    
    c - the collection to transfer elements into
    
    Returns:
    
    the number of elements transferred
    
    Throws:
    
    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
```
public int drainTo(Collection<? super E> c,
                   int maxElements)
```
    Description copied from interface: BlockingQueue
    
    Removes at most the given number of available elements from this queue and adds them to the given collection. A failure encountered while attempting to add elements to collection c may result in elements being in neither, either or both collections when the associated exception is thrown. Attempts to drain 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.
    
    Specified by:
    
    drainTo in interface BlockingQueue<E>
    
    Parameters:
    
    c - the collection to transfer elements into
    
    maxElements - the maximum number of elements to transfer
    
    Returns:
    
    the number of elements transferred
    
    Throws:
    
    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
  - push
```
public void push(E e)
```
    Description copied from interface: BlockingDeque
    
    Pushes an element onto the stack represented by this deque (in other words, at the head of this deque) if it is possible to do so immediately without violating capacity restrictions, throwing an IllegalStateException if no space is currently available.
    This method is equivalent to addFirst.
    
    Specified by:
    
    push in interface BlockingDeque<E>
    
    Specified by:
    
    push in interface Deque<E>
    
    Parameters:
    
    e - the element to push
    
    Throws:
    
    IllegalStateException - if this deque is full
    
    NullPointerException - if the specified element is null
  - pop
```
public E pop()
```
    Description copied from interface: Deque
    
    Pops an element from the stack represented by this deque. In other words, removes and returns the first element of this deque.
    This method is equivalent to Deque.removeFirst().
    
    Specified by:
    
    pop in interface Deque<E>
    
    Returns:
    
    the element at the front of this deque (which is the top of the stack represented by this deque)
    
    Throws:
    
    NoSuchElementException - if this deque is empty
  - remove
```
public boolean remove(Object o)
```
    Removes the first occurrence of the specified element from this deque. If the deque does not contain the element, it is unchanged. More formally, removes the first element e such that o.equals(e) (if such an element exists). Returns true if this deque contained the specified element (or equivalently, if this deque changed as a result of the call).
    This method is equivalent to removeFirstOccurrence.
    
    Specified by:
    
    remove in interface Collection<E>
    
    Specified by:
    
    remove in interface BlockingDeque<E>
    
    Specified by:
    
    remove in interface BlockingQueue<E>
    
    Specified by:
    
    remove in interface Deque<E>
    
    Overrides:
    
    remove in class AbstractCollection<E>
    
    Parameters:
    
    o - element to be removed from this deque, if present
    
    Returns:
    
    true if this deque changed as a result of the call
  - size
```
public int size()
```
    Returns the number of elements in this deque.
    
    Specified by:
    
    size in interface Collection<E>
    
    Specified by:
    
    size in interface BlockingDeque<E>
    
    Specified by:
    
    size in interface Deque<E>
    
    Specified by:
    
    size in class AbstractCollection<E>
    
    Returns:
    
    the number of elements in this deque
  - contains
```
public boolean contains(Object o)
```
    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).
    
    Specified by:
    
    contains in interface Collection<E>
    
    Specified by:
    
    contains in interface BlockingDeque<E>
    
    Specified by:
    
    contains in interface BlockingQueue<E>
    
    Specified by:
    
    contains in interface Deque<E>
    
    Overrides:
    
    contains in class AbstractCollection<E>
    
    Parameters:
    
    o - object to be checked for containment in this deque
    
    Returns:
    
    true if this deque contains the specified element
  - toArray
```
public Object[] toArray()
```
    Returns an array containing all of the elements in this deque, in proper sequence (from first to last element).
    The returned array will be "safe" in that no references to it are maintained by this deque. (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.
    
    Specified by:
    
    toArray in interface Collection<E>
    
    Overrides:
    
    toArray in class AbstractCollection<E>
    
    Returns:
    
    an array containing all of the elements in this deque
  - toArray
```
public <T> T[] toArray(T[] a)
```
    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. If the deque 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 deque.
    If this deque fits in the specified array with room to spare (i.e., the array has more elements than this deque), the element in the array immediately following the end of the deque 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 deque known to contain only strings. The following code can be used to dump the deque 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().
    Specified by:
    
    toArray in interface Collection<E>
    
    Overrides:
    
    toArray in class AbstractCollection<E>
    
    Type Parameters:
    
    T - the runtime type of the array to contain the collection
    
    Parameters:
    
    a - the array into which the elements of the deque are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose
    
    Returns:
    
    an array containing all of the elements in this deque
    
    Throws:
    
    ArrayStoreException - if the runtime type of the specified array is not a supertype of the runtime type of every element in this deque
    
    NullPointerException - if the specified array is null
  - toString
```
public String toString()
```
    Description copied from class: AbstractCollection
    
    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).
    
    Overrides:
    
    toString in class AbstractCollection<E>
    
    Returns:
    
    a string representation of this collection
  - clear
```
public void clear()
```
    Atomically removes all of the elements from this deque. The deque will be empty after this call returns.
    
    Specified by:
    
    clear in interface Collection<E>
    
    Overrides:
    
    clear in class AbstractQueue<E>
  - iterator
```
public Iterator<E> iterator()
```
    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.
    
    Specified by:
    
    iterator in interface Iterable<E>
    
    Specified by:
    
    iterator in interface Collection<E>
    
    Specified by:
    
    iterator in interface BlockingDeque<E>
    
    Specified by:
    
    iterator in interface Deque<E>
    
    Specified by:
    
    iterator in class AbstractCollection<E>
    
    Returns:
    
    an iterator over the elements in this deque in proper sequence
  - descendingIterator
```
public Iterator<E> descendingIterator()
```
    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.
    
    Specified by:
    
    descendingIterator in interface Deque<E>
    
    Returns:
    
    an iterator over the elements in this deque in reverse order
  - spliterator
```
public Spliterator<E> spliterator()
```
    Returns a Spliterator over the elements in this deque.
    The returned spliterator is weakly consistent.
    
    The Spliterator reports Spliterator.CONCURRENT, Spliterator.ORDERED, and Spliterator.NONNULL.
    
    Specified by:
    
    spliterator in interface Iterable<E>
    
    Specified by:
    
    spliterator in interface Collection<E>
    
    Implementation Note:
    
    The Spliterator implements trySplit to permit limited parallelism.
    
    Returns:
    
    a Spliterator over the elements in this deque
    
    Since:
    
    1.8

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Java compact1, compact2, compact3 java.util.concurrent Class LinkedBlockingDeque<E>（JDK8）

Class LinkedBlockingDeque<E>

Constructor Summary

Method Summary

Methods inherited from class java.util.AbstractQueue

Methods inherited from class java.util.AbstractCollection

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Collection

Methods inherited from interface java.lang.Iterable

Constructor Detail

LinkedBlockingDeque

LinkedBlockingDeque

LinkedBlockingDeque

Method Detail

addFirst

addLast

offerFirst

offerLast

putFirst

putLast

offerFirst

offerLast

removeFirst

removeLast

pollFirst

pollLast

takeFirst

takeLast

pollFirst

pollLast

getFirst

getLast

peekFirst

peekLast

removeFirstOccurrence

removeLastOccurrence

add

offer

put

offer

remove

poll

take

poll

element

peek

remainingCapacity

drainTo

drainTo

push

pop

remove

size

contains

toArray

toArray

toString

clear

iterator

descendingIterator

spliterator