LinkedBlockingDeque (core API)

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

Type Parameters:
E - the type of elements held in this collection

All Implemented Interfaces:

BlockingDeque<E>, Deque<E>, java.io.Serializable, java.lang.Iterable<E>, java.util.Collection<E>, java.util.concurrent.BlockingQueue<E>, java.util.Queue<E>

Direct Known Subclasses:

DefaultImageTaskExecutor.LinkedBlockingStack
```
public class LinkedBlockingDeque<E>
extends java.util.AbstractQueue<E>
implements BlockingDeque<E>, java.io.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(java.util.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

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(java.lang.Object o)` Returns `true` if this deque contains the specified element.
`java.util.Iterator<E>`	`descendingIterator()` Returns an iterator over the elements in this deque in reverse sequential order.
`int`	`drainTo(java.util.Collection<? super E> c)`
`int`	`drainTo(java.util.Collection<? super E> c, int maxElements)`
`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.
`java.util.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, java.util.concurrent.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, java.util.concurrent.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, java.util.concurrent.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, java.util.concurrent.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, java.util.concurrent.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, java.util.concurrent.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.
`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(java.lang.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(java.lang.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(java.lang.Object o)` Removes the last occurrence of the specified element from this deque.
`int`	`size()` Returns the number of 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.
`java.lang.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.
`java.lang.String`	`toString()`

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, removeAll, retainAll

- 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:
    
    java.lang.IllegalArgumentException - if capacity is less than 1
  - LinkedBlockingDeque
```
public LinkedBlockingDeque(java.util.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:
    
    java.lang.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:
    
    java.lang.IllegalStateException - if the element cannot be added at this time due to capacity restrictions
    
    java.lang.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:
    
    java.lang.IllegalStateException - if the element cannot be added at this time due to capacity restrictions
    
    java.lang.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:
    
    java.lang.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:
    
    java.lang.NullPointerException - if the specified element is null
  - putFirst
```
public void putFirst(E e)
              throws java.lang.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:
    
    java.lang.NullPointerException - if the specified element is null
    
    java.lang.InterruptedException - if interrupted while waiting
  - putLast
```
public void putLast(E e)
             throws java.lang.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:
    
    java.lang.NullPointerException - if the specified element is null
    
    java.lang.InterruptedException - if interrupted while waiting
  - offerFirst
```
public boolean offerFirst(E e,
                 long timeout,
                 java.util.concurrent.TimeUnit unit)
                   throws java.lang.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:
    
    java.lang.NullPointerException - if the specified element is null
    
    java.lang.InterruptedException - if interrupted while waiting
  - offerLast
```
public boolean offerLast(E e,
                long timeout,
                java.util.concurrent.TimeUnit unit)
                  throws java.lang.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:
    
    java.lang.NullPointerException - if the specified element is null
    
    java.lang.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:
    
    java.util.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:
    
    java.util.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 java.lang.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:
    
    java.lang.InterruptedException - if interrupted while waiting
  - takeLast
```
public E takeLast()
           throws java.lang.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:
    
    java.lang.InterruptedException - if interrupted while waiting
  - pollFirst
```
public E pollFirst(long timeout,
          java.util.concurrent.TimeUnit unit)
            throws java.lang.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:
    
    java.lang.InterruptedException - if interrupted while waiting
  - pollLast
```
public E pollLast(long timeout,
         java.util.concurrent.TimeUnit unit)
           throws java.lang.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:
    
    java.lang.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:
    
    java.util.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:
    
    java.util.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(java.lang.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(java.lang.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 BlockingDeque<E>
    
    Specified by:
    
    add in interface Deque<E>
    
    Specified by:
    
    add in interface java.util.Collection<E>
    
    Specified by:
    
    add in interface java.util.concurrent.BlockingQueue<E>
    
    Specified by:
    
    add in interface java.util.Queue<E>
    
    Overrides:
    
    add in class java.util.AbstractQueue<E>
    
    Parameters:
    e - the element to add
    
    Returns:
    true (as specified by Collection.add(E))
    
    Throws:
    
    java.lang.IllegalStateException - if the element cannot be added at this time due to capacity restrictions
    
    java.lang.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 Deque<E>
    
    Specified by:
    
    offer in interface java.util.concurrent.BlockingQueue<E>
    
    Specified by:
    
    offer in interface java.util.Queue<E>
    
    Parameters:
    e - the element to add
    
    Returns:
    true if the element was added to this deque, else false
    
    Throws:
    
    java.lang.NullPointerException - if the specified element is null
  - put
```
public void put(E e)
         throws java.lang.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 java.util.concurrent.BlockingQueue<E>
    
    Parameters:
    e - the element to add
    
    Throws:
    
    java.lang.NullPointerException - if the specified element is null
    
    java.lang.InterruptedException
  - offer
```
public boolean offer(E e,
            long timeout,
            java.util.concurrent.TimeUnit unit)
              throws java.lang.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 java.util.concurrent.BlockingQueue<E>
    
    Parameters:
    e - the element to add
    
    Returns:
    true if the element was added to this deque, else false
    
    Throws:
    
    java.lang.NullPointerException - if the specified element is null
    
    java.lang.InterruptedException
  - 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 java.util.Queue<E>
    
    Overrides:
    
    remove in class java.util.AbstractQueue<E>
    
    Returns:
    the head of the queue represented by this deque
    
    Throws:
    
    java.util.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 java.util.Queue<E>
    
    Returns:
    the head of this deque, or null if this deque is empty
  - take
```
public E take()
       throws java.lang.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 java.util.concurrent.BlockingQueue<E>
    
    Returns:
    the head of this deque
    
    Throws:
    
    java.lang.InterruptedException - if interrupted while waiting
  - poll
```
public E poll(long timeout,
     java.util.concurrent.TimeUnit unit)
       throws java.lang.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 java.util.concurrent.BlockingQueue<E>
    
    Returns:
    the head of this deque, or null if the specified waiting time elapses before an element is available
    
    Throws:
    
    java.lang.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 java.util.Queue<E>
    
    Overrides:
    
    element in class java.util.AbstractQueue<E>
    
    Returns:
    the head of the queue represented by this deque
    
    Throws:
    
    java.util.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 java.util.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 java.util.concurrent.BlockingQueue<E>
  - drainTo
```
public int drainTo(java.util.Collection<? super E> c)
```
    Specified by:
    
    drainTo in interface java.util.concurrent.BlockingQueue<E>
    
    Throws:
    
    java.lang.UnsupportedOperationException
    
    java.lang.ClassCastException
    
    java.lang.NullPointerException
    
    java.lang.IllegalArgumentException
  - drainTo
```
public int drainTo(java.util.Collection<? super E> c,
          int maxElements)
```
    Specified by:
    
    drainTo in interface java.util.concurrent.BlockingQueue<E>
    
    Throws:
    
    java.lang.UnsupportedOperationException
    
    java.lang.ClassCastException
    
    java.lang.NullPointerException
    
    java.lang.IllegalArgumentException
  - push
```
public void push(E e)
```
    Description copied from interface: BlockingDeque
    
    Pushes an element onto the stack represented by this deque. In other words, inserts the element at the front of this deque unless it would violate capacity restrictions.
    
    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:
    
    java.lang.IllegalStateException - if the element cannot be added at this time due to capacity restrictions
    
    java.lang.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:
    
    java.util.NoSuchElementException - if this deque is empty
  - remove
```
public boolean remove(java.lang.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 BlockingDeque<E>
    
    Specified by:
    
    remove in interface Deque<E>
    
    Specified by:
    
    remove in interface java.util.Collection<E>
    
    Specified by:
    
    remove in interface java.util.concurrent.BlockingQueue<E>
    
    Overrides:
    
    remove in class java.util.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 BlockingDeque<E>
    
    Specified by:
    
    size in interface Deque<E>
    
    Specified by:
    
    size in interface java.util.Collection<E>
    
    Specified by:
    
    size in class java.util.AbstractCollection<E>
    
    Returns:
    the number of elements in this deque
  - contains
```
public boolean contains(java.lang.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 BlockingDeque<E>
    
    Specified by:
    
    contains in interface Deque<E>
    
    Specified by:
    
    contains in interface java.util.Collection<E>
    
    Specified by:
    
    contains in interface java.util.concurrent.BlockingQueue<E>
    
    Overrides:
    
    contains in class java.util.AbstractCollection<E>
    
    Parameters:
    o - object to be checked for containment in this deque
    
    Returns:
    true if this deque contains the specified element
  - toArray
```
public java.lang.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 java.util.Collection<E>
    
    Overrides:
    
    toArray in class java.util.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 java.util.Collection<E>
    
    Overrides:
    
    toArray in class java.util.AbstractCollection<E>
    
    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:
    
    java.lang.ArrayStoreException - if the runtime type of the specified array is not a supertype of the runtime type of every element in this deque
    
    java.lang.NullPointerException - if the specified array is null
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.util.AbstractCollection<E>
  - 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 java.util.Collection<E>
    
    Overrides:
    
    clear in class java.util.AbstractQueue<E>
  - iterator
```
public java.util.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 a "weakly consistent" iterator that will never throw ConcurrentModificationException, and guarantees to traverse elements as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect any modifications subsequent to construction.
    
    Specified by:
    
    iterator in interface BlockingDeque<E>
    
    Specified by:
    
    iterator in interface Deque<E>
    
    Specified by:
    
    iterator in interface java.lang.Iterable<E>
    
    Specified by:
    
    iterator in interface java.util.Collection<E>
    
    Specified by:
    
    iterator in class java.util.AbstractCollection<E>
    
    Returns:
    an iterator over the elements in this deque in proper sequence
  - descendingIterator
```
public java.util.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 a "weakly consistent" iterator that will never throw ConcurrentModificationException, and guarantees to traverse elements as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect any modifications subsequent to construction.
    
    Specified by:
    
    descendingIterator in interface Deque<E>
    
    Returns:
    an iterator over the elements in this deque in reverse order

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

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