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| java.util.concurrent.BlockingDeque<E> |
 Known Indirect Subclasses
|
A 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.
| Public Methods | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
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. | |||||||||||
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. | |||||||||||
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. | |||||||||||
Returns
true if this deque contains the specified element. | |||||||||||
Retrieves, but does not remove, the head of the queue represented by
this deque (in other words, the first element of this deque).
| |||||||||||
Returns an iterator over the elements in this deque in proper sequence.
| |||||||||||
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. | |||||||||||
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.
| |||||||||||
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. | |||||||||||
Inserts the specified element at the front of this deque,
waiting up to the specified wait time if necessary for space to
become available.
| |||||||||||
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. | |||||||||||
Inserts the specified element at the end of this deque,
waiting up to the specified wait time if necessary for space to
become available.
| |||||||||||
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. | |||||||||||
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. | |||||||||||
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.
| |||||||||||
Retrieves and removes the first element of this deque, waiting
up to the specified wait time if necessary for an element to
become available.
| |||||||||||
Retrieves and removes the last element of this deque, waiting
up to the specified wait time if necessary for an element to
become available.
| |||||||||||
Pushes an element onto the stack represented by this deque.
| |||||||||||
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.
| |||||||||||
Inserts the specified element at the front of this deque,
waiting if necessary for space to become available.
| |||||||||||
Inserts the specified element at the end of this deque,
waiting if necessary for space to become available.
| |||||||||||
Retrieves and removes the head of the queue represented by this deque
(in other words, the first element of this deque).
| |||||||||||
Removes the first occurrence of the specified element from this deque.
| |||||||||||
Removes the first occurrence of the specified element from this deque.
| |||||||||||
Removes the last occurrence of the specified element from this deque.
| |||||||||||
Returns the number of elements in this deque.
| |||||||||||
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.
| |||||||||||
Retrieves and removes the first element of this deque, waiting
if necessary until an element becomes available.
| |||||||||||
Retrieves and removes the last element of this deque, waiting
if necessary until an element becomes available.
| |||||||||||
|
[Expand]
Inherited Methods | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
From interface
java.lang.Iterable
| |||||||||||
|
From interface
java.util.Collection
| |||||||||||
|
From interface
java.util.Deque
| |||||||||||
|
From interface
java.util.Queue
| |||||||||||
|
From interface
java.util.concurrent.BlockingQueue
| |||||||||||
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 addLast.
| e | the element to add |
|---|
add(E))| IllegalStateException | |
|---|---|
| ClassCastException | if the class of the specified element prevents it from being added to this deque |
| NullPointerException | if the specified element is null |
| IllegalArgumentException | if some property of the specified element prevents it from being added to this deque |
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.
| e | the element to add |
|---|
| IllegalStateException | |
|---|---|
| ClassCastException | |
| NullPointerException | if the specified element is null |
| IllegalArgumentException |
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.
| e | the element to add |
|---|
| IllegalStateException | |
|---|---|
| ClassCastException | |
| NullPointerException | if the specified element is null |
| IllegalArgumentException |
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).
| o | object to be checked for containment in this deque |
|---|
true if this deque contains the specified element| ClassCastException | if the class of the specified element is incompatible with this deque (optional) |
|---|---|
| NullPointerException | if the specified element is null (optional) |
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 getFirst.
| NoSuchElementException | if this deque is empty |
|---|
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).
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(E) method, which can fail to
insert an element only by throwing an exception.
This method is equivalent to offerLast.
| e | the element to add |
|---|
| ClassCastException | if the class of the specified element prevents it from being added to this deque |
|---|---|
| NullPointerException | if the specified element is null |
| IllegalArgumentException | if some property of the specified element prevents it from being added to this deque |
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.
| 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 |
true if the element was added to this deque, else
false| InterruptedException | |
|---|---|
| ClassCastException | if the class of the specified element prevents it from being added to this deque |
| NullPointerException | if the specified element is null |
| IllegalArgumentException | if some property of the specified element prevents it from being added to this deque |
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.
| e | the element to add |
|---|
| ClassCastException | |
|---|---|
| NullPointerException | if the specified element is null |
| IllegalArgumentException |
Inserts the specified element at the front of this deque, waiting up to the specified wait time if necessary for space to become available.
| 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 |
true if successful, or false if
the specified waiting time elapses before space is available| InterruptedException | if interrupted while waiting |
|---|---|
| ClassCastException | if the class of the specified element prevents it from being added to this deque |
| NullPointerException | if the specified element is null |
| IllegalArgumentException | if some property of the specified element prevents it from being added to this deque |
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.
| e | the element to add |
|---|
| ClassCastException | |
|---|---|
| NullPointerException | if the specified element is null |
| IllegalArgumentException |
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 | 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 |
true if successful, or false if
the specified waiting time elapses before space is available| InterruptedException | if interrupted while waiting |
|---|---|
| ClassCastException | if the class of the specified element prevents it from being added to this deque |
| NullPointerException | if the specified element is null |
| IllegalArgumentException | if some property of the specified element prevents it from being added to this 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 peekFirst.
null if this deque is empty
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 pollFirst().
null if this deque is empty
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.
| timeout | how long to wait before giving up, in units of
unit |
|---|---|
| unit | a TimeUnit determining how to interpret the
timeout parameter |
null if the
specified waiting time elapses before an element is available| InterruptedException | if interrupted while waiting |
|---|
Retrieves and removes the first element of this deque, waiting up to the specified wait time if necessary for an element to become available.
| timeout | how long to wait before giving up, in units of
unit |
|---|---|
| unit | a TimeUnit determining how to interpret the
timeout parameter |
null if the specified
waiting time elapses before an element is available| InterruptedException | if interrupted while waiting |
|---|
Retrieves and removes the last element of this deque, waiting up to the specified wait time if necessary for an element to become available.
| timeout | how long to wait before giving up, in units of
unit |
|---|---|
| unit | a TimeUnit determining how to interpret the
timeout parameter |
null if the specified
waiting time elapses before an element is available| InterruptedException | if interrupted while waiting |
|---|
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.
| e | the element to push |
|---|
| IllegalStateException | |
|---|---|
| ClassCastException | |
| NullPointerException | if the specified element is null |
| IllegalArgumentException |
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.
| e | the element to add |
|---|
| InterruptedException | |
|---|---|
| ClassCastException | if the class of the specified element prevents it from being added to this deque |
| NullPointerException | if the specified element is null |
| IllegalArgumentException | if some property of the specified element prevents it from being added to this deque |
Inserts the specified element at the front of this deque, waiting if necessary for space to become available.
| e | the element to add |
|---|
| InterruptedException | if interrupted while waiting |
|---|---|
| ClassCastException | if the class of the specified element prevents it from being added to this deque |
| NullPointerException | if the specified element is null |
| IllegalArgumentException | if some property of the specified element prevents it from being added to this deque |
Inserts the specified element at the end of this deque, waiting if necessary for space to become available.
| e | the element to add |
|---|
| InterruptedException | if interrupted while waiting |
|---|---|
| ClassCastException | if the class of the specified element prevents it from being added to this deque |
| NullPointerException | if the specified element is null |
| IllegalArgumentException | if some property of the specified element prevents it from being added to this deque |
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 removeFirst.
| NoSuchElementException | if this deque is empty |
|---|
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.
| o | element to be removed from this deque, if present |
|---|
true if this deque changed as a result of the call| ClassCastException | if the class of the specified element is incompatible with this deque (optional) |
|---|---|
| NullPointerException | if the specified element is null (optional) |
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).
| o | element to be removed from this deque, if present |
|---|
true if an element was removed as a result of this call| ClassCastException | if the class of the specified element is incompatible with this deque (optional) |
|---|---|
| NullPointerException | if the specified element is null (optional) |
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).
| o | element to be removed from this deque, if present |
|---|
true if an element was removed as a result of this call| ClassCastException | if the class of the specified element is incompatible with this deque (optional) |
|---|---|
| NullPointerException | if the specified element is null (optional) |
Returns the number of elements in this deque.
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.
| InterruptedException | if interrupted while waiting |
|---|
Retrieves and removes the first element of this deque, waiting if necessary until an element becomes available.
| InterruptedException | if interrupted while waiting |
|---|
Retrieves and removes the last element of this deque, waiting if necessary until an element becomes available.
| InterruptedException | if interrupted while waiting |
|---|