edu.emory.mathcs.backport.java.util.concurrent
public interface BlockingDeque extends BlockingQueue, Deque
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 {@code BlockingDeque} happen-before actions subsequent to the access or removal of that element from the {@code BlockingDeque} in another thread.
This interface is a member of the Java Collections Framework.
Since: 1.6
Method Summary | |
---|---|
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.
|
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. |
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. |
boolean | contains(Object o)
Returns true if this deque contains the specified element.
|
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).
|
Iterator | iterator()
Returns an iterator over the elements in this deque in proper sequence.
|
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. |
boolean | offer(Object e, long timeout, TimeUnit unit)
Inserts the specified element into the queue represented by this deque
(in other words, at the tail of this deque), waiting up to the
specified wait time if necessary for space to become available.
|
boolean | offerFirst(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.
|
boolean | offerFirst(Object e, long timeout, TimeUnit unit)
Inserts the specified element at the front of this deque,
waiting up to the specified wait time if necessary for space to
become available.
|
boolean | offerLast(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.
|
boolean | offerLast(Object e, long timeout, TimeUnit unit)
Inserts the specified element at the end of this deque,
waiting up to the specified wait time if necessary for space to
become available.
|
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.
|
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.
|
Object | poll(long timeout, TimeUnit unit)
Retrieves and removes the head of the queue represented by this deque
(in other words, the first element of this deque), waiting up to the
specified wait time if necessary for an element to become available.
|
Object | pollFirst(long timeout, TimeUnit unit)
Retrieves and removes the first element of this deque, waiting
up to the specified wait time if necessary for an element to
become available.
|
Object | pollLast(long timeout, TimeUnit unit)
Retrieves and removes the last element of this deque, waiting
up to the specified wait time if necessary for an element to
become available.
|
void | push(Object e)
Pushes an element onto the stack represented by this deque. |
void | put(Object 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(Object e)
Inserts the specified element at the front of this deque,
waiting if necessary for space to become available.
|
void | putLast(Object e)
Inserts the specified element at the end of this deque,
waiting if necessary for space to become available.
|
Object | remove()
Retrieves and removes the head of the queue represented by this deque
(in other words, the first element of this deque).
|
boolean | remove(Object o)
Removes the first occurrence of the specified element from this deque.
|
boolean | removeFirstOccurrence(Object o)
Removes the first occurrence of the specified element from this deque.
|
boolean | removeLastOccurrence(Object o)
Removes the last occurrence of the specified element from this deque.
|
int | size()
Returns the number of elements in this deque.
|
Object | 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.
|
Object | takeFirst()
Retrieves and removes the first element of this deque, waiting
if necessary until an element becomes available.
|
Object | takeLast()
Retrieves and removes the last element of this deque, waiting
if necessary until an element becomes available.
|
offer
.
This method is equivalent to addLast
.
Parameters: e the element to add
Throws: IllegalStateException {@inheritDoc } 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
offerFirst
.
Parameters: e the element to add
Throws: IllegalStateException {@inheritDoc } ClassCastException {@inheritDoc } NullPointerException if the specified element is null IllegalArgumentException {@inheritDoc }
offerLast
.
Parameters: e the element to add
Throws: IllegalStateException {@inheritDoc } ClassCastException {@inheritDoc } NullPointerException if the specified element is null IllegalArgumentException {@inheritDoc }
Parameters: o object to be checked for containment in this deque
Returns: true if this deque contains the specified element
Throws: ClassCastException if the class of the specified element is incompatible with this deque (optional) NullPointerException if the specified element is null (optional)
peek
only in that it throws an
exception if this deque is empty.
This method is equivalent to getFirst
.
Returns: the head of this deque
Throws: NoSuchElementException if this deque is empty
Returns: an iterator over the elements in this deque in proper sequence
This method is equivalent to offerLast
.
Parameters: e the element to add
Throws: 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
This method is equivalent to
offerLast
.
Parameters: e the element to add
Returns: true if the element was added to this deque, else false
Throws: InterruptedException {@inheritDoc } 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
addFirst
method, which can
fail to insert an element only by throwing an exception.
Parameters: e the element to add
Throws: ClassCastException {@inheritDoc } NullPointerException if the specified element is null IllegalArgumentException {@inheritDoc }
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: 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
addLast
method, which can
fail to insert an element only by throwing an exception.
Parameters: e the element to add
Throws: ClassCastException {@inheritDoc } NullPointerException if the specified element is null IllegalArgumentException {@inheritDoc }
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: 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
This method is equivalent to peekFirst
.
Returns: the head of this deque, or null if this deque is empty
This method is equivalent to BlockingDeque.
Returns: the head of this deque, or null if this deque is empty
This method is equivalent to
pollFirst
.
Returns: the head of this deque, or null if the specified waiting time elapses before an element is available
Throws: InterruptedException if interrupted while waiting
Parameters: timeout how long to wait before giving up, in units of unit unit a TimeUnit determining how to interpret the timeout parameter
Returns: the head of this deque, or null if the specified waiting time elapses before an element is available
Throws: InterruptedException if interrupted while waiting
Parameters: timeout how long to wait before giving up, in units of unit unit a TimeUnit determining how to interpret the timeout parameter
Returns: the tail of this deque, or null if the specified waiting time elapses before an element is available
Throws: InterruptedException if interrupted while waiting
This method is equivalent to addFirst
.
Throws: IllegalStateException {@inheritDoc } ClassCastException {@inheritDoc } NullPointerException if the specified element is null IllegalArgumentException {@inheritDoc }
This method is equivalent to putLast
.
Parameters: e the element to add
Throws: InterruptedException {@inheritDoc } 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
Parameters: e the element to add
Throws: 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
Parameters: e the element to add
Throws: 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
poll
only in that it
throws an exception if this deque is empty.
This method is equivalent to removeFirst
.
Returns: the head of the queue represented by this deque
Throws: NoSuchElementException if this deque is empty
This method is equivalent to
removeFirstOccurrence
.
Parameters: o element to be removed from this deque, if present
Returns: true if this deque changed as a result of the call
Throws: ClassCastException if the class of the specified element is incompatible with this deque (optional) NullPointerException if the specified element is null (optional)
Parameters: o element to be removed from this deque, if present
Returns: true if an element was removed as a result of this call
Throws: ClassCastException if the class of the specified element is incompatible with this deque (optional) NullPointerException if the specified element is null (optional)
Parameters: o element to be removed from this deque, if present
Returns: true if an element was removed as a result of this call
Throws: 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
This method is equivalent to takeFirst
.
Returns: the head of this deque
Throws: InterruptedException if interrupted while waiting
Returns: the head of this deque
Throws: InterruptedException if interrupted while waiting
Returns: the tail of this deque
Throws: InterruptedException if interrupted while waiting