net.sf.beanlib.util.concurrent
Class LinkedBlockingDeque<E>

java.lang.Object
  java.util.AbstractCollection<E>
      java.util.AbstractQueue<E>
          net.sf.beanlib.util.concurrent.LinkedBlockingDeque<E>

Type Parameters:

E - the type of elements held in this collection

All Implemented Interfaces:

Serializable, Iterable<E>, Collection<E>, BlockingQueue<E>, Queue<E>, BlockingDeque<E>, Deque<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

Author:

Doug Lea

See Also:

Serialized Form

Nested Class Summary

private class	LinkedBlockingDeque.AbstractItr Base class for Iterators for LinkedBlockingDeque
private class	LinkedBlockingDeque.DescendingItr Descending iterator for LinkedBlockingDeque
private class	LinkedBlockingDeque.Itr Forward iterator
(package private) static class	LinkedBlockingDeque.Node<E> Doubly-linked list node class

Field Summary

private int	capacity Maximum number of items in the deque
private int	count Number of items in the deque
private LinkedBlockingDeque.Node<E>	first Pointer to first node
private LinkedBlockingDeque.Node<E>	last Pointer to last node
private ReentrantLock	lock Main lock guarding all access
private Condition	notEmpty Condition for waiting takes
private Condition	notFull Condition for waiting puts
private static long	serialVersionUID

Constructor Summary

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

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.
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.
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)
int	drainTo(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.
Iterator<E>	iterator() Returns an iterator over the elements in this deque in proper sequence.
private boolean	linkFirst(E e) Links e as first element, or returns false if full.
private boolean	linkLast(E e) Links e as last element, or returns false if full.
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 as the lest element of this deque, if possible.
boolean	offerFirst(E e) Inserts the specified element at the front of this deque unless it would violate capacity restrictions.
boolean	offerFirst(E e, long timeout, TimeUnit unit) Inserts the specified element as the first element of this deque, waiting if necessary up to the specified wait time for space to become available.
boolean	offerLast(E e) Inserts the specified element at the end of this deque unless it would violate capacity restrictions.
boolean	offerLast(E e, long timeout, TimeUnit unit) Inserts the specified element as the last element of this deque, waiting if necessary up to the specified wait time 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 first element of this deque, waiting if necessary up to the specified wait time if no elements are present on this deque.
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 if necessary up to the specified wait time if no elements are present on this deque.
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 if necessary up to the specified wait time if no elements are present on this deque.
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, returning true upon success and throwing an IllegalStateException if no space is currently available.
void	put(E e) Adds the specified element as the last element of this deque, waiting if necessary for space to become available.
void	putFirst(E e) Adds the specified element as the first element of this deque, waiting if necessary for space to become available.
void	putLast(E e) Adds the specified element as the last element of this deque, waiting if necessary for space to become available.
private void	readObject(ObjectInputStream s) Reconstitute this deque from a stream (that is, deserialize it).
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.
(package private) boolean	removeNode(LinkedBlockingDeque.Node<E> e) Variant of removeFirstOccurrence needed by iterator.remove.
int	size() Returns the number of elements in this deque.
E	take() Retrieves and removes the first element of this deque, waiting if no elements are present on this deque.
E	takeFirst() Retrieves and removes the first element of this deque, waiting if no elements are present on this deque.
E	takeLast() Retrieves and removes the last element of this deque, waiting if no elements are present on this deque.
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()
private void	unlink(LinkedBlockingDeque.Node<E> x) Unlink e
private E	unlinkFirst() Removes and returns first element, or null if empty.
private E	unlinkLast() Removes and returns last element, or null if empty.
private void	writeObject(ObjectOutputStream s) Save the state of this deque to a stream (that is, serialize it).

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

Methods inherited from interface java.util.Collection

addAll, containsAll, equals, hashCode, isEmpty, removeAll, retainAll

Field Detail

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

first

private transient LinkedBlockingDeque.Node<E> first

Pointer to first node

last

private transient LinkedBlockingDeque.Node<E> last

Pointer to last node

count

private transient int count

Number of items in the deque

capacity

private final int capacity

Maximum number of items in the deque

lock

private final ReentrantLock lock

Main lock guarding all access

notEmpty

private final Condition notEmpty

Condition for waiting takes

notFull

private final Condition notFull

Condition for waiting puts

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

linkFirst

private boolean linkFirst(E e)

Links e as first element, or returns false if full.

linkLast

private boolean linkLast(E e)

Links e as last element, or returns false if full.

unlinkFirst

private E unlinkFirst()

Removes and returns first element, or null if empty.

unlinkLast

private E unlinkLast()

Removes and returns last element, or null if empty.

unlink

private void unlink(LinkedBlockingDeque.Node<E> x)

Unlink e

addFirst

public void addFirst(E e)

Description copied from interface: Deque

Inserts the specified element at the front of this deque if it is possible to do so immediately without violating capacity restrictions. When using a capacity-restricted deque, it is generally preferable to use method Deque.offerFirst(E).

Specified by:

addFirst in interface Deque<E>

Parameters:

e - the element to add

Throws:

IllegalStateException - if the element cannot be added at this time due to capacity restrictions

NullPointerException - if the specified element is null and this deque does not permit null elements

addLast

public void addLast(E e)

Description copied from interface: Deque

Inserts the specified element at the end of this deque if it is possible to do so immediately without violating capacity restrictions. When using a capacity-restricted deque, it is generally preferable to use method Deque.offerLast(E).

This method is equivalent to Deque.add(E).

Specified by:

addLast in interface Deque<E>

Parameters:

e - the element to add

Throws:

IllegalStateException - if the element cannot be added at this time due to capacity restrictions

NullPointerException - if the specified element is null and this deque does not permit null elements

offerFirst

public boolean offerFirst(E e)

Description copied from interface: Deque

Inserts the specified element at the front of this deque unless it would violate capacity restrictions. When using a capacity-restricted deque, this method is generally preferable to the Deque.addFirst(E) method, which can fail to insert an element only by throwing an exception.

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 and this deque does not permit null elements

offerLast

public boolean offerLast(E e)

Description copied from interface: Deque

Inserts the specified element at the end of this deque unless it would violate capacity restrictions. When using a capacity-restricted deque, this method is generally preferable to the Deque.addLast(E) method, which can fail to insert an element only by throwing an exception.

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 and this deque does not permit null elements

putFirst

public void putFirst(E e)
              throws InterruptedException

Description copied from interface: BlockingDeque

Adds the specified element as the first element 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

Adds the specified element as the last element 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 as the first element of this deque, waiting if necessary up to the specified wait time 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 as the last element of this deque, waiting if necessary up to the specified wait time 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 no elements are present on this deque.

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 no elements are present on this deque.

Specified by:

takeLast in interface BlockingDeque<E>

Returns:

the head 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 if necessary up to the specified wait time if no elements are present on this deque.

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 present.

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 if necessary up to the specified wait time if no elements are present on this deque.

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 head of this deque, or null if the specified waiting time elapses before an element is present.

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: Deque

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==null ? e==null : 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 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: Deque

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==null ? e==null : 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 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 BlockingQueue<E>

Specified by:

add in interface Deque<E>

Overrides:

add in class AbstractQueue<E>

Parameters:

e - the element to add

Returns:

true (as specified by Collection.add(E))

Throws:

IllegalStateException - if the element cannot be added at this time due to capacity restrictions

NullPointerException - if the specified element is null

offer

public boolean offer(E e)

Description copied from interface: Deque

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 Deque.add(E) method, which can fail to insert an element only by throwing an exception.

This method is equivalent to Deque.offerLast(E).

Specified by:

offer in interface BlockingQueue<E>

Specified by:

offer in interface Queue<E>

Specified by:

offer 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

put

public void put(E e)
         throws InterruptedException

Description copied from interface: BlockingDeque

Adds the specified element as the last element of this deque, waiting if necessary for space to become available. This method is equivalent to to putLast

Specified by:

put in interface BlockingQueue<E>

Specified by:

put in interface BlockingDeque<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 as the lest element of this deque, if possible. When using deques that may impose insertion restrictions (for example capacity bounds), method offer is generally preferable to method Collection.add(E), which can fail to insert an element only by throwing an exception. This method is equivalent to to offerLast

Specified by:

offer in interface BlockingQueue<E>

Specified by:

offer in interface BlockingDeque<E>

Parameters:

e - the element to add.

Returns:

true if it was possible to add the element to this deque, else false

Throws:

NullPointerException - if the specified element is null

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 Queue<E>

Specified by:

remove in interface Deque<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: Deque

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 Queue<E>

Specified by:

poll in interface Deque<E>

Returns:

the first element 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 first element of this deque, waiting if no elements are present on this deque. This method is equivalent to to takeFirst

Specified by:

take in interface BlockingQueue<E>

Specified by:

take in interface BlockingDeque<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 first element of this deque, waiting if necessary up to the specified wait time if no elements are present on this deque. This method is equivalent to to pollFirst

Specified by:

poll in interface BlockingQueue<E>

Specified by:

poll 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 present.

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 Queue<E>

Specified by:

element in interface Deque<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: Deque

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 Deque.peekFirst().

Specified by:

peek in interface Queue<E>

Specified by:

peek in interface Deque<E>

Returns:

the head of the queue represented by 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>

drainTo

public int drainTo(Collection<? super E> c)

Specified by:

drainTo in interface BlockingQueue<E>

Throws:

UnsupportedOperationException

ClassCastException

NullPointerException

IllegalArgumentException

drainTo

public int drainTo(Collection<? super E> c,
                   int maxElements)

Specified by:

drainTo in interface BlockingQueue<E>

Throws:

UnsupportedOperationException

ClassCastException

NullPointerException

IllegalArgumentException

push

public void push(E e)

Description copied from interface: Deque

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, returning true upon success and throwing an IllegalStateException if no space is currently available.

This method is equivalent to Deque.addFirst(E).

Specified by:

push in interface Deque<E>

Parameters:

e - the element to push

Throws:

IllegalStateException - if the element cannot be added at this time due to capacity restrictions

NullPointerException - if the specified element is null and this deque does not permit null elements

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 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 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 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

removeNode

boolean removeNode(LinkedBlockingDeque.Node<E> e)

Variant of removeFirstOccurrence needed by iterator.remove. Searches for the node, not its contents.

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>

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()

Overrides:

toString in class 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 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 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 Iterable<E>

Specified by:

iterator in interface Collection<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 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 sequence

writeObject

private void writeObject(ObjectOutputStream s)
                  throws IOException

Save the state of this deque to a stream (that is, serialize it).

Parameters:

s - the stream

Throws:

IOException

readObject

private void readObject(ObjectInputStream s)
                 throws IOException,
                        ClassNotFoundException

Reconstitute this deque from a stream (that is, deserialize it).

Parameters:

s - the stream

Throws:

IOException

ClassNotFoundException