edu.emory.mathcs.backport.java.util.concurrent
public class LinkedBlockingDeque extends AbstractQueue implements BlockingDeque, java.io.Serializable
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.
Constructor and Description |
---|
LinkedBlockingDeque()
Creates a LinkedBlockingDeque with a capacity of
Integer.MAX_VALUE . |
LinkedBlockingDeque(java.util.Collection 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.
|
Modifier and Type | Method and Description |
---|---|
boolean |
add(java.lang.Object e)
Inserts the specified element at the end of this deque unless it would
violate capacity restrictions.
|
void |
addFirst(java.lang.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(java.lang.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.
|
void |
clear()
Atomically removes all of the elements from this deque.
|
boolean |
contains(java.lang.Object o)
Returns true if this deque contains the specified element.
|
java.util.Iterator |
descendingIterator()
Returns an iterator over the elements in this deque in reverse
sequential order.
|
int |
drainTo(java.util.Collection c)
Removes all available elements from this queue and adds them
to the given collection.
|
int |
drainTo(java.util.Collection c,
int maxElements)
Removes at most the given number of available elements from
this queue and adds them to the given collection.
|
java.lang.Object |
element()
Retrieves, but does not remove, the head of the queue represented by
this deque.
|
java.lang.Object |
getFirst()
Retrieves, but does not remove, the first element of this deque.
|
java.lang.Object |
getLast()
Retrieves, but does not remove, the last element of this deque.
|
java.util.Iterator |
iterator()
Returns an iterator over the elements in this deque in proper sequence.
|
boolean |
offer(java.lang.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(java.lang.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(java.lang.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(java.lang.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(java.lang.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(java.lang.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.
|
java.lang.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.
|
java.lang.Object |
peekFirst()
Retrieves, but does not remove, the first element of this deque,
or returns null if this deque is empty.
|
java.lang.Object |
peekLast()
Retrieves, but does not remove, the last element of this deque,
or returns null if this deque is empty.
|
java.lang.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.
|
java.lang.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.
|
java.lang.Object |
pollFirst()
Retrieves and removes the first element of this deque,
or returns null if this deque is empty.
|
java.lang.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.
|
java.lang.Object |
pollLast()
Retrieves and removes the last element of this deque,
or returns null if this deque is empty.
|
java.lang.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.
|
java.lang.Object |
pop()
Pops an element from the stack represented by this deque.
|
void |
push(java.lang.Object e)
Pushes an element onto the stack represented by this deque.
|
void |
put(java.lang.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(java.lang.Object e)
Inserts the specified element at the front of this deque,
waiting if necessary for space to become available.
|
void |
putLast(java.lang.Object e)
Inserts the specified element at the end of this deque,
waiting if necessary for space to become available.
|
int |
remainingCapacity()
Returns the number of additional elements that this deque can ideally
(in the absence of memory or resource constraints) accept without
blocking.
|
java.lang.Object |
remove()
Retrieves and removes the head of the queue represented by this deque.
|
boolean |
remove(java.lang.Object o)
Removes the first occurrence of the specified element from this deque.
|
java.lang.Object |
removeFirst()
Retrieves and removes the first element of this deque.
|
boolean |
removeFirstOccurrence(java.lang.Object o)
Removes the first occurrence of the specified element from this deque.
|
java.lang.Object |
removeLast()
Retrieves and removes the last element of this deque.
|
boolean |
removeLastOccurrence(java.lang.Object o)
Removes the last occurrence of the specified element from this deque.
|
int |
size()
Returns the number of elements in this deque.
|
java.lang.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.
|
java.lang.Object |
takeFirst()
Retrieves and removes the first element of this deque, waiting
if necessary until an element becomes available.
|
java.lang.Object |
takeLast()
Retrieves and removes the last element of this deque, waiting
if necessary until an element becomes available.
|
java.lang.Object[] |
toArray()
Returns an array containing all of the elements in this deque, in
proper sequence (from first to last element).
|
java.lang.Object[] |
toArray(java.lang.Object[] 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.
|
java.lang.String |
toString() |
addAll
containsAll, isEmpty, removeAll, retainAll
public LinkedBlockingDeque()
Integer.MAX_VALUE
.public LinkedBlockingDeque(int capacity)
capacity
- the capacity of this dequejava.lang.IllegalArgumentException
- if capacity is less than 1public LinkedBlockingDeque(java.util.Collection c)
Integer.MAX_VALUE
, initially containing the elements of
the given collection, added in traversal order of the
collection's iterator.c
- the collection of elements to initially containjava.lang.NullPointerException
- if the specified collection or any
of its elements are nullpublic void addFirst(java.lang.Object e)
BlockingDeque
offerFirst
.addFirst
in interface BlockingDeque
addFirst
in interface Deque
e
- the element to addjava.lang.IllegalStateException
- if the element cannot be added at this
time due to capacity restrictionsjava.lang.NullPointerException
- if the specified element is nullpublic void addLast(java.lang.Object e)
BlockingDeque
offerLast
.addLast
in interface BlockingDeque
addLast
in interface Deque
e
- the element to addjava.lang.IllegalStateException
- if the element cannot be added at this
time due to capacity restrictionsjava.lang.NullPointerException
- if the specified element is nullpublic boolean offerFirst(java.lang.Object e)
BlockingDeque
addFirst
method, which can
fail to insert an element only by throwing an exception.offerFirst
in interface BlockingDeque
offerFirst
in interface Deque
e
- the element to addjava.lang.NullPointerException
- if the specified element is nullpublic boolean offerLast(java.lang.Object e)
BlockingDeque
addLast
method, which can
fail to insert an element only by throwing an exception.offerLast
in interface BlockingDeque
offerLast
in interface Deque
e
- the element to addjava.lang.NullPointerException
- if the specified element is nullpublic void putFirst(java.lang.Object e) throws java.lang.InterruptedException
BlockingDeque
putFirst
in interface BlockingDeque
e
- the element to addjava.lang.NullPointerException
- if the specified element is nulljava.lang.InterruptedException
- if interrupted while waitingpublic void putLast(java.lang.Object e) throws java.lang.InterruptedException
BlockingDeque
putLast
in interface BlockingDeque
e
- the element to addjava.lang.NullPointerException
- if the specified element is nulljava.lang.InterruptedException
- if interrupted while waitingpublic boolean offerFirst(java.lang.Object e, long timeout, TimeUnit unit) throws java.lang.InterruptedException
BlockingDeque
offerFirst
in interface BlockingDeque
e
- the element to addtimeout
- how long to wait before giving up, in units of
unitunit
- a TimeUnit determining how to interpret the
timeout parameterjava.lang.NullPointerException
- if the specified element is nulljava.lang.InterruptedException
- if interrupted while waitingpublic boolean offerLast(java.lang.Object e, long timeout, TimeUnit unit) throws java.lang.InterruptedException
BlockingDeque
offerLast
in interface BlockingDeque
e
- the element to addtimeout
- how long to wait before giving up, in units of
unitunit
- a TimeUnit determining how to interpret the
timeout parameterjava.lang.NullPointerException
- if the specified element is nulljava.lang.InterruptedException
- if interrupted while waitingpublic java.lang.Object removeFirst()
Deque
pollFirst
only in that it throws an
exception if this deque is empty.removeFirst
in interface Deque
java.util.NoSuchElementException
public java.lang.Object removeLast()
Deque
pollLast
only in that it throws an
exception if this deque is empty.removeLast
in interface Deque
java.util.NoSuchElementException
public java.lang.Object pollFirst()
Deque
public java.lang.Object pollLast()
Deque
public java.lang.Object takeFirst() throws java.lang.InterruptedException
BlockingDeque
takeFirst
in interface BlockingDeque
java.lang.InterruptedException
- if interrupted while waitingpublic java.lang.Object takeLast() throws java.lang.InterruptedException
BlockingDeque
takeLast
in interface BlockingDeque
java.lang.InterruptedException
- if interrupted while waitingpublic java.lang.Object pollFirst(long timeout, TimeUnit unit) throws java.lang.InterruptedException
BlockingDeque
pollFirst
in interface BlockingDeque
timeout
- how long to wait before giving up, in units of
unitunit
- a TimeUnit determining how to interpret the
timeout parameterjava.lang.InterruptedException
- if interrupted while waitingpublic java.lang.Object pollLast(long timeout, TimeUnit unit) throws java.lang.InterruptedException
BlockingDeque
pollLast
in interface BlockingDeque
timeout
- how long to wait before giving up, in units of
unitunit
- a TimeUnit determining how to interpret the
timeout parameterjava.lang.InterruptedException
- if interrupted while waitingpublic java.lang.Object getFirst()
Deque
peekFirst
only in that it
throws an exception if this deque is empty.public java.lang.Object getLast()
Deque
peekLast
only in that it
throws an exception if this deque is empty.public java.lang.Object peekFirst()
Deque
public java.lang.Object peekLast()
Deque
public boolean removeFirstOccurrence(java.lang.Object o)
BlockingDeque
removeFirstOccurrence
in interface BlockingDeque
removeFirstOccurrence
in interface Deque
o
- element to be removed from this deque, if presentpublic boolean removeLastOccurrence(java.lang.Object o)
BlockingDeque
removeLastOccurrence
in interface BlockingDeque
removeLastOccurrence
in interface Deque
o
- element to be removed from this deque, if presentpublic boolean add(java.lang.Object e)
offer
.
This method is equivalent to addLast(java.lang.Object)
.
add
in interface BlockingDeque
add
in interface BlockingQueue
add
in interface Deque
add
in interface Queue
add
in interface java.util.Collection
add
in class AbstractQueue
e
- the element to addCollection.add(java.lang.Object)
)java.lang.IllegalStateException
- if the element cannot be added at this
time due to capacity restrictionsjava.lang.NullPointerException
- if the specified element is nullpublic boolean offer(java.lang.Object e)
BlockingDeque
BlockingDeque.add(java.lang.Object)
method, which can fail to
insert an element only by throwing an exception.
This method is equivalent to offerLast
.
offer
in interface BlockingDeque
offer
in interface BlockingQueue
offer
in interface Deque
offer
in interface Queue
e
- the element to addjava.lang.NullPointerException
- if the specified element is nullpublic void put(java.lang.Object e) throws java.lang.InterruptedException
BlockingDeque
This method is equivalent to putLast
.
put
in interface BlockingDeque
put
in interface BlockingQueue
e
- the element to addjava.lang.NullPointerException
- if the specified element is nulljava.lang.InterruptedException
- if interrupted while waitingpublic boolean offer(java.lang.Object e, long timeout, TimeUnit unit) throws java.lang.InterruptedException
BlockingDeque
This method is equivalent to
offerLast
.
offer
in interface BlockingDeque
offer
in interface BlockingQueue
e
- the element to addtimeout
- how long to wait before giving up, in units of
unitunit
- a TimeUnit determining how to interpret the
timeout parameterjava.lang.NullPointerException
- if the specified element is nulljava.lang.InterruptedException
- if interrupted while waitingpublic java.lang.Object remove()
poll
only in that it throws an
exception if this deque is empty.
This method is equivalent to removeFirst
.
remove
in interface BlockingDeque
remove
in interface Deque
remove
in interface Queue
remove
in class AbstractQueue
java.util.NoSuchElementException
- if this deque is emptypublic java.lang.Object poll()
BlockingDeque
This method is equivalent to Deque.pollFirst()
.
public java.lang.Object take() throws java.lang.InterruptedException
BlockingDeque
This method is equivalent to takeFirst
.
take
in interface BlockingDeque
take
in interface BlockingQueue
java.lang.InterruptedException
- if interrupted while waitingpublic java.lang.Object poll(long timeout, TimeUnit unit) throws java.lang.InterruptedException
BlockingDeque
This method is equivalent to
pollFirst
.
poll
in interface BlockingDeque
poll
in interface BlockingQueue
timeout
- how long to wait before giving up, in units of
unitunit
- a TimeUnit determining how to interpret the
timeout parameterjava.lang.InterruptedException
- if interrupted while waitingpublic java.lang.Object element()
peek
only in that
it throws an exception if this deque is empty.
This method is equivalent to getFirst
.
element
in interface BlockingDeque
element
in interface Deque
element
in interface Queue
element
in class AbstractQueue
java.util.NoSuchElementException
- if this deque is emptypublic java.lang.Object peek()
BlockingDeque
This method is equivalent to peekFirst
.
public int remainingCapacity()
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.
remainingCapacity
in interface BlockingQueue
public int drainTo(java.util.Collection c)
BlockingQueue
drainTo
in interface BlockingQueue
c
- the collection to transfer elements intojava.lang.UnsupportedOperationException
- if addition of elements
is not supported by the specified collectionjava.lang.ClassCastException
- if the class of an element of this queue
prevents it from being added to the specified collectionjava.lang.NullPointerException
- if the specified collection is nulljava.lang.IllegalArgumentException
- if the specified collection is this
queue, or some property of an element of this queue prevents
it from being added to the specified collectionpublic int drainTo(java.util.Collection c, int maxElements)
BlockingQueue
drainTo
in interface BlockingQueue
c
- the collection to transfer elements intomaxElements
- the maximum number of elements to transferjava.lang.UnsupportedOperationException
- if addition of elements
is not supported by the specified collectionjava.lang.ClassCastException
- if the class of an element of this queue
prevents it from being added to the specified collectionjava.lang.NullPointerException
- if the specified collection is nulljava.lang.IllegalArgumentException
- if the specified collection is this
queue, or some property of an element of this queue prevents
it from being added to the specified collectionpublic void push(java.lang.Object e)
BlockingDeque
This method is equivalent to addFirst
.
push
in interface BlockingDeque
push
in interface Deque
e
- the element to pushjava.lang.IllegalStateException
- if the element cannot be added at this
time due to capacity restrictionsjava.lang.NullPointerException
- if the specified element is nullpublic java.lang.Object pop()
Deque
This method is equivalent to Deque.removeFirst()
.
public boolean remove(java.lang.Object o)
This method is equivalent to
removeFirstOccurrence
.
remove
in interface BlockingDeque
remove
in interface BlockingQueue
remove
in interface Deque
remove
in interface java.util.Collection
remove
in class java.util.AbstractCollection
o
- element to be removed from this deque, if presentpublic int size()
size
in interface BlockingDeque
size
in interface Deque
size
in interface java.util.Collection
size
in class java.util.AbstractCollection
public boolean contains(java.lang.Object o)
contains
in interface BlockingDeque
contains
in interface BlockingQueue
contains
in interface Deque
contains
in interface java.util.Collection
contains
in class java.util.AbstractCollection
o
- object to be checked for containment in this dequepublic java.lang.Object[] toArray()
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.
toArray
in interface java.util.Collection
toArray
in class AbstractCollection
public java.lang.Object[] toArray(java.lang.Object[] a)
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().
toArray
in interface java.util.Collection
toArray
in class AbstractCollection
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 purposejava.lang.ArrayStoreException
- if the runtime type of the specified array
is not a supertype of the runtime type of every element in
this dequejava.lang.NullPointerException
- if the specified array is nullpublic java.lang.String toString()
toString
in class java.util.AbstractCollection
public void clear()
clear
in interface java.util.Collection
clear
in class AbstractQueue
public java.util.Iterator iterator()
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.iterator
in interface BlockingDeque
iterator
in interface Deque
iterator
in interface java.lang.Iterable
iterator
in interface java.util.Collection
iterator
in class java.util.AbstractCollection
public java.util.Iterator descendingIterator()
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.descendingIterator
in interface Deque