BlockingDeque<E>
Java SE 6
| public interface java.util.concurrent BlockingDeque<E>
|
Java SE 6 |
Deque that additionally supports blocking operations that wait
for the deque to become non-empty when retrieving an element, and wait for
space to become available in the deque when storing an element.
BlockingDeque methods come in four forms, with different ways of handling operations that cannot be satisfied immediately, but may be satisfied at some point in the future: one throws an exception, the second returns a special value (either null or false, depending on the operation), the third blocks the current thread indefinitely until the operation can succeed, and the fourth blocks for only a given maximum time limit before giving up. These methods are summarized in the following table:
| First Element (Head) | ||||
| Throws exception | Special value | Blocks | Times out | |
| Insert | addFirst(e) |
offerFirst(e) |
putFirst(e) |
offerFirst(e, time, unit) |
| Remove | removeFirst() |
pollFirst() |
takeFirst() |
pollFirst(time, unit) |
| Examine | getFirst() |
peekFirst() |
not applicable | not applicable |
| Last Element (Tail) | ||||
| Throws exception | Special value | Blocks | Times out | |
| Insert | addLast(e) |
offerLast(e) |
putLast(e) |
offerLast(e, time, unit) |
| Remove | removeLast() |
pollLast() |
takeLast() |
pollLast(time, unit) |
| Examine | getLast() |
peekLast() |
not applicable | not applicable |
Like any BlockingQueue, a BlockingDeque is thread safe,
does not permit null elements, and may (or may not) be
capacity-constrained.
A BlockingDeque implementation may be used directly as a FIFO BlockingQueue. The methods inherited from the BlockingQueue interface are precisely equivalent to BlockingDeque methods as indicated in the following table:
| BlockingQueue Method | Equivalent BlockingDeque Method |
| Insert | |
add(e) |
addLast(e) |
offer(e) |
offerLast(e) |
put(e) |
putLast(e) |
offer(e, time, unit) |
offerLast(e, time, unit) |
| Remove | |
remove() |
removeFirst() |
poll() |
pollFirst() |
take() |
takeFirst() |
poll(time, unit) |
pollFirst(time, unit) |
| Examine | |
element() |
getFirst() |
peek() |
peekFirst() |
Memory consistency effects: As with other concurrent
collections, actions in a thread prior to placing an object into a
BlockingDeque
happen-before
actions subsequent to the access or removal of that element from
the BlockingDeque in another thread.
This interface is a member of the Java Collections Framework.
| since | 1.6 |
| E | the type of elements held in this collection |
| Methods | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| public boolean | add(Object 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 throwing an IllegalStateException if no space is currently available. When using a capacity-restricted deque, it is generally preferable to use offer.
This method is equivalent to
| ||||||||||||||||
| public void | addFirst(Object 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. When using a capacity-restricted deque, it is generally preferable to use offerFirst.
| ||||||||||||||||
| public void | addLast(Object 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. When using a capacity-restricted deque, it is generally preferable to use offerLast.
| ||||||||||||||||
| 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).
| ||||||||||||||||
| public Object | element() Retrieves, but does not remove, the head of the queue represented by this deque (in other words, the first element of this deque). This method differs from peek only in that it throws an
exception if this deque is empty.
This method is equivalent to
| ||||||||||||||||
| public Iterator | 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).
| ||||||||||||||||
| public boolean | offer(Object 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. When using a capacity-restricted deque, this method is generally preferable to the #add method, which can fail to
insert an element only by throwing an exception.
This method is equivalent to
| ||||||||||||||||
| public boolean | offer(Object e, long timeout, TimeUnit unit) throws InterruptedException 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
| ||||||||||||||||
| public boolean | offerFirst(Object 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. 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.
| ||||||||||||||||
| public boolean | offerFirst(Object e, long timeout, TimeUnit unit) throws InterruptedException Inserts the specified element at the front of this deque, waiting up to the specified wait time if necessary for space to become available.
| ||||||||||||||||
| public boolean | offerLast(Object 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. 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.
| ||||||||||||||||
| public boolean | offerLast(Object e, long timeout, TimeUnit unit) throws InterruptedException Inserts the specified element at the end of this deque, waiting up to the specified wait time if necessary for space to become available.
| ||||||||||||||||
| public Object | 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. This method is equivalent to
| ||||||||||||||||
| public Object | 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. This method is equivalent to
| ||||||||||||||||
| public Object | poll(long timeout, TimeUnit unit) throws InterruptedException 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
| ||||||||||||||||
| public Object | pollFirst(long timeout, TimeUnit unit) throws InterruptedException Retrieves and removes the first element of this deque, waiting up to the specified wait time if necessary for an element to become available.
| ||||||||||||||||
| public Object | pollLast(long timeout, TimeUnit unit) throws InterruptedException Retrieves and removes the last element of this deque, waiting up to the specified wait time if necessary for an element to become available.
| ||||||||||||||||
| public void | push(Object e) 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
| ||||||||||||||||
| public void | put(Object e) throws InterruptedException 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
| ||||||||||||||||
| public void | putFirst(Object e) throws InterruptedException Inserts the specified element at the front of this deque, waiting if necessary for space to become available.
| ||||||||||||||||
| public void | putLast(Object e) throws InterruptedException Inserts the specified element at the end of this deque, waiting if necessary for space to become available.
| ||||||||||||||||
| public Object | remove() Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque). This method differs from poll only in that it
throws an exception if this deque is empty.
This method is equivalent to
| ||||||||||||||||
| 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
| ||||||||||||||||
| public boolean | removeFirstOccurrence(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).
| ||||||||||||||||
| public boolean | removeLastOccurrence(Object o) 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).
| ||||||||||||||||
| public int | size() Returns the number of elements in this deque.
| ||||||||||||||||
| public Object | take() throws InterruptedException 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
| ||||||||||||||||
| public Object | takeFirst() throws InterruptedException Retrieves and removes the first element of this deque, waiting if necessary until an element becomes available.
| ||||||||||||||||
| public Object | takeLast() throws InterruptedException Retrieves and removes the last element of this deque, waiting if necessary until an element becomes available.
| ||||||||||||||||
| About DocWeb · Bundles · Export · Export All | Top 10 · Statistics · Login |
| About Sun · Contact · Privacy · Terms of Use · Trademarks | Java SE 6 · Copyright © 1994-2009 Sun Microsystems, Inc.All rights reserved. Use is subject to license terms |
 |
 |
|