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public interface BlockingDeque extends Deque
A {@link 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 | {@link #addFirst addFirst(e)} | {@link #offerFirst(Object) offerFirst(e)} | {@link #putFirst putFirst(e)} | {@link #offerFirst(Object, long, TimeUnit) offerFirst(e, time, unit)} |
Remove | {@link #removeFirst removeFirst()} | {@link #pollFirst pollFirst()} | {@link #takeFirst takeFirst()} | {@link #pollFirst(long, TimeUnit) pollFirst(time, unit)} |
Examine | {@link #getFirst getFirst()} | {@link #peekFirst peekFirst()} | not applicable | not applicable |
Last Element (Tail) | ||||
Throws exception | Special value | Blocks | Times out | |
Insert | {@link #addLast addLast(e)} | {@link #offerLast(Object) offerLast(e)} | {@link #putLast putLast(e)} | {@link #offerLast(Object, long, TimeUnit) offerLast(e, time, unit)} |
Remove | {@link #removeLast() removeLast()} | {@link #pollLast() pollLast()} | {@link #takeLast takeLast()} | {@link #pollLast(long, TimeUnit) pollLast(time, unit)} |
Examine | {@link #getLast getLast()} | {@link #peekLast peekLast()} | not applicable | not applicable |
Like any {@link 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 | |
{@link #add(Object) add(e)} | {@link #addLast(Object) addLast(e)} |
{@link #offer(Object) offer(e)} | {@link #offerLast(Object) offerLast(e)} |
{@link #put(Object) put(e)} | {@link #putLast(Object) putLast(e)} |
{@link #offer(Object, long, TimeUnit) offer(e, time, unit)} | {@link #offerLast(Object, long, TimeUnit) offerLast(e, time, unit)} |
Remove | |
{@link #remove() remove()} | {@link #removeFirst() removeFirst()} |
{@link #poll() poll()} | {@link #pollFirst() pollFirst()} |
{@link #take() take()} | {@link #takeFirst() takeFirst()} |
{@link #poll(long, TimeUnit) poll(time, unit)} | {@link #pollFirst(long, TimeUnit) pollFirst(time, unit)} |
Examine | |
{@link #element() element()} | {@link #getFirst() getFirst()} |
{@link #peek() peek()} | {@link #peekFirst() 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.
Method Summary | |
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boolean |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
Pushes an element onto the stack represented by this deque. |
void |
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 |
Inserts the specified element at the front of this deque, waiting if necessary for space to become available. |
void |
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 |
Removes the first occurrence of the specified element from this deque. |
boolean |
Removes the first occurrence of the specified element from this deque. |
boolean |
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 |
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. |
Methods inherited from class java.util.Deque |
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add, addFirst, addLast, contains, descendingIterator, element, getFirst, getLast, iterator, offer, offerFirst, offerLast, peek, peekFirst, peekLast, poll, pollFirst, pollLast, pop, push, remove, remove, removeFirst, removeFirstOccurrence, removeLast, removeLastOccurrence, size |
Methods inherited from class java.util.Queue |
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add, element, offer, peek, poll, remove |
Methods inherited from class java.util.Collection |
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add, addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray |
Methods inherited from class java.lang.Iterable |
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iterator |
Method Detail |
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public boolean add(Object e)
This method is equivalent to {@link #addLast(Object) addLast}.
e
- the element to addpublic void addFirst(Object e)
e
- the element to addpublic void addLast(Object e)
e
- the element to addpublic boolean contains(Object o)
o
- object to be checked for containment in this dequepublic Object element()
This method is equivalent to {@link #getFirst() getFirst}.
public Iterator iterator()
public boolean offer(Object e)
This method is equivalent to {@link #offerLast(Object) offerLast}.
e
- the element to addpublic boolean offer(Object e, long timeout, TimeUnit unit) throws InterruptedException
This method is equivalent to {@link #offerLast(Object,long,TimeUnit) offerLast}.
e
- the element to addtimeout
unit
InterruptedException
- {@inheritDoc}public boolean offerFirst(Object e)
e
- the element to addpublic boolean offerFirst(Object e, long timeout, TimeUnit unit) throws InterruptedException
e
- the element to addtimeout
- how long to wait before giving up, in units of
unitunit
- a TimeUnit determining how to interpret the
timeout parameterInterruptedException
- if interrupted while waitingpublic boolean offerLast(Object e)
e
- the element to addpublic boolean offerLast(Object e, long timeout, TimeUnit unit) throws InterruptedException
e
- the element to addtimeout
- how long to wait before giving up, in units of
unitunit
- a TimeUnit determining how to interpret the
timeout parameterInterruptedException
- if interrupted while waitingpublic Object peek()
This method is equivalent to {@link #peekFirst() peekFirst}.
public Object poll()
This method is equivalent to {@link #pollFirst()}.
public Object poll(long timeout, TimeUnit unit) throws InterruptedException
This method is equivalent to {@link #pollFirst(long,TimeUnit) pollFirst}.
timeout
unit
InterruptedException
- if interrupted while waitingpublic Object pollFirst(long timeout, TimeUnit unit) throws InterruptedException
timeout
- how long to wait before giving up, in units of
unitunit
- a TimeUnit determining how to interpret the
timeout parameterInterruptedException
- if interrupted while waitingpublic Object pollLast(long timeout, TimeUnit unit) throws InterruptedException
timeout
- how long to wait before giving up, in units of
unitunit
- a TimeUnit determining how to interpret the
timeout parameterInterruptedException
- if interrupted while waitingpublic void push(Object e)
This method is equivalent to {@link #addFirst(Object) addFirst}.
e
public void put(Object e) throws InterruptedException
This method is equivalent to {@link #putLast(Object) putLast}.
e
- the element to addInterruptedException
- {@inheritDoc}public void putFirst(Object e) throws InterruptedException
e
- the element to addInterruptedException
- if interrupted while waitingpublic void putLast(Object e) throws InterruptedException
e
- the element to addInterruptedException
- if interrupted while waitingpublic Object remove()
This method is equivalent to {@link #removeFirst() removeFirst}.
public boolean remove(Object o)
This method is equivalent to {@link #removeFirstOccurrence(Object) removeFirstOccurrence}.
o
- element to be removed from this deque, if presentpublic boolean removeFirstOccurrence(Object o)
o
- element to be removed from this deque, if presentpublic boolean removeLastOccurrence(Object o)
o
- element to be removed from this deque, if presentpublic int size()
public Object take() throws InterruptedException
This method is equivalent to {@link #takeFirst() takeFirst}.
InterruptedException
- if interrupted while waitingpublic Object takeFirst() throws InterruptedException
InterruptedException
- if interrupted while waitingpublic Object takeLast() throws InterruptedException
InterruptedException
- if interrupted while waiting
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