E
- the type of elements held in this collectionpublic class LinkedBlockingDeque<E> extends java.util.AbstractQueue<E> implements BlockingDeque<E>, 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<? extends E> 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(E e)
Inserts the specified element at the end of this deque unless it would
violate capacity restrictions.
|
void |
addFirst(E 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(E 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<E> |
descendingIterator()
Returns an iterator over the elements in this deque in reverse
sequential order.
|
int |
drainTo(java.util.Collection<? super E> c) |
int |
drainTo(java.util.Collection<? super E> c,
int maxElements) |
E |
element()
Retrieves, but does not remove, the head of the queue represented by
this deque.
|
E |
getFirst()
Retrieves, but does not remove, the first element of this deque.
|
E |
getLast()
Retrieves, but does not remove, the last element of this deque.
|
java.util.Iterator<E> |
iterator()
Returns an iterator over the elements in this deque in proper sequence.
|
boolean |
offer(E 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(E e,
long timeout,
java.util.concurrent.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(E 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(E e,
long timeout,
java.util.concurrent.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(E 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(E e,
long timeout,
java.util.concurrent.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.
|
E |
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.
|
E |
peekFirst()
Retrieves, but does not remove, the first element of this deque,
or returns null if this deque is empty.
|
E |
peekLast()
Retrieves, but does not remove, the last element of this deque,
or returns null if this deque is empty.
|
E |
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.
|
E |
poll(long timeout,
java.util.concurrent.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.
|
E |
pollFirst()
Retrieves and removes the first element of this deque,
or returns null if this deque is empty.
|
E |
pollFirst(long timeout,
java.util.concurrent.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.
|
E |
pollLast()
Retrieves and removes the last element of this deque,
or returns null if this deque is empty.
|
E |
pollLast(long timeout,
java.util.concurrent.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.
|
E |
pop()
Pops an element from the stack represented by this deque.
|
void |
push(E e)
Pushes an element onto the stack represented by this deque.
|
void |
put(E 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(E e)
Inserts the specified element at the front of this deque,
waiting if necessary for space to become available.
|
void |
putLast(E 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.
|
E |
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.
|
E |
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.
|
E |
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.
|
E |
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.
|
E |
takeFirst()
Retrieves and removes the first element of this deque, waiting
if necessary until an element becomes available.
|
E |
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).
|
<T> T[] |
toArray(T[] 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() |
containsAll, isEmpty, removeAll, retainAll
public LinkedBlockingDeque()
LinkedBlockingDeque
with a capacity of
Integer.MAX_VALUE
.public LinkedBlockingDeque(int capacity)
LinkedBlockingDeque
with the given (fixed) capacity.capacity
- the capacity of this dequejava.lang.IllegalArgumentException
- if capacity
is less than 1public LinkedBlockingDeque(java.util.Collection<? extends E> c)
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.c
- the collection of elements to initially containjava.lang.NullPointerException
- if the specified collection or any
of its elements are nullpublic void addFirst(E e)
BlockingDeque
offerFirst
.addFirst
in interface BlockingDeque<E>
addFirst
in interface Deque<E>
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(E e)
BlockingDeque
offerLast
.addLast
in interface BlockingDeque<E>
addLast
in interface Deque<E>
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(E e)
BlockingDeque
addFirst
method, which can
fail to insert an element only by throwing an exception.offerFirst
in interface BlockingDeque<E>
offerFirst
in interface Deque<E>
e
- the element to addjava.lang.NullPointerException
- if the specified element is nullpublic boolean offerLast(E e)
BlockingDeque
addLast
method, which can
fail to insert an element only by throwing an exception.public void putFirst(E e) throws java.lang.InterruptedException
BlockingDeque
putFirst
in interface BlockingDeque<E>
e
- the element to addjava.lang.NullPointerException
- if the specified element is nulljava.lang.InterruptedException
- if interrupted while waitingpublic void putLast(E e) throws java.lang.InterruptedException
BlockingDeque
putLast
in interface BlockingDeque<E>
e
- the element to addjava.lang.NullPointerException
- if the specified element is nulljava.lang.InterruptedException
- if interrupted while waitingpublic boolean offerFirst(E e, long timeout, java.util.concurrent.TimeUnit unit) throws java.lang.InterruptedException
BlockingDeque
offerFirst
in interface BlockingDeque<E>
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(E e, long timeout, java.util.concurrent.TimeUnit unit) throws java.lang.InterruptedException
BlockingDeque
offerLast
in interface BlockingDeque<E>
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 E removeFirst()
Deque
pollFirst
only in that it throws an
exception if this deque is empty.removeFirst
in interface Deque<E>
java.util.NoSuchElementException
- if this deque is emptypublic E removeLast()
Deque
pollLast
only in that it throws an
exception if this deque is empty.removeLast
in interface Deque<E>
java.util.NoSuchElementException
- if this deque is emptypublic E pollFirst()
Deque
public E pollLast()
Deque
public E takeFirst() throws java.lang.InterruptedException
BlockingDeque
takeFirst
in interface BlockingDeque<E>
java.lang.InterruptedException
- if interrupted while waitingpublic E takeLast() throws java.lang.InterruptedException
BlockingDeque
takeLast
in interface BlockingDeque<E>
java.lang.InterruptedException
- if interrupted while waitingpublic E pollFirst(long timeout, java.util.concurrent.TimeUnit unit) throws java.lang.InterruptedException
BlockingDeque
pollFirst
in interface BlockingDeque<E>
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 E pollLast(long timeout, java.util.concurrent.TimeUnit unit) throws java.lang.InterruptedException
BlockingDeque
pollLast
in interface BlockingDeque<E>
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 E getFirst()
Deque
peekFirst
only in that it
throws an exception if this deque is empty.public E getLast()
Deque
peekLast
only in that it
throws an exception if this deque is empty.public E peekFirst()
Deque
public E peekLast()
Deque
public boolean removeFirstOccurrence(java.lang.Object o)
BlockingDeque
removeFirstOccurrence
in interface BlockingDeque<E>
removeFirstOccurrence
in interface Deque<E>
o
- element to be removed from this deque, if presentpublic boolean removeLastOccurrence(java.lang.Object o)
BlockingDeque
removeLastOccurrence
in interface BlockingDeque<E>
removeLastOccurrence
in interface Deque<E>
o
- element to be removed from this deque, if presentpublic boolean add(E e)
offer
.
This method is equivalent to addLast(E)
.
add
in interface BlockingDeque<E>
add
in interface Deque<E>
add
in interface java.util.Collection<E>
add
in interface java.util.concurrent.BlockingQueue<E>
add
in interface java.util.Queue<E>
add
in class java.util.AbstractQueue<E>
e
- the element to addCollection.add(E)
)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(E e)
BlockingDeque
BlockingDeque.add(E)
method, which can fail to
insert an element only by throwing an exception.
This method is equivalent to offerLast
.
offer
in interface BlockingDeque<E>
offer
in interface Deque<E>
offer
in interface java.util.concurrent.BlockingQueue<E>
offer
in interface java.util.Queue<E>
e
- the element to addjava.lang.NullPointerException
- if the specified element is nullpublic void put(E e) throws java.lang.InterruptedException
BlockingDeque
This method is equivalent to putLast
.
put
in interface BlockingDeque<E>
put
in interface java.util.concurrent.BlockingQueue<E>
e
- the element to addjava.lang.NullPointerException
- if the specified element is nulljava.lang.InterruptedException
public boolean offer(E e, long timeout, java.util.concurrent.TimeUnit unit) throws java.lang.InterruptedException
BlockingDeque
This method is equivalent to
offerLast
.
offer
in interface BlockingDeque<E>
offer
in interface java.util.concurrent.BlockingQueue<E>
e
- the element to addjava.lang.NullPointerException
- if the specified element is nulljava.lang.InterruptedException
public E remove()
poll
only in that it throws an
exception if this deque is empty.
This method is equivalent to removeFirst
.
remove
in interface BlockingDeque<E>
remove
in interface Deque<E>
remove
in interface java.util.Queue<E>
remove
in class java.util.AbstractQueue<E>
java.util.NoSuchElementException
- if this deque is emptypublic E poll()
BlockingDeque
This method is equivalent to Deque.pollFirst()
.
public E take() throws java.lang.InterruptedException
BlockingDeque
This method is equivalent to takeFirst
.
take
in interface BlockingDeque<E>
take
in interface java.util.concurrent.BlockingQueue<E>
java.lang.InterruptedException
- if interrupted while waitingpublic E poll(long timeout, java.util.concurrent.TimeUnit unit) throws java.lang.InterruptedException
BlockingDeque
This method is equivalent to
pollFirst
.
poll
in interface BlockingDeque<E>
poll
in interface java.util.concurrent.BlockingQueue<E>
java.lang.InterruptedException
- if interrupted while waitingpublic E element()
peek
only in that
it throws an exception if this deque is empty.
This method is equivalent to getFirst
.
element
in interface BlockingDeque<E>
element
in interface Deque<E>
element
in interface java.util.Queue<E>
element
in class java.util.AbstractQueue<E>
java.util.NoSuchElementException
- if this deque is emptypublic E peek()
BlockingDeque
This method is equivalent to peekFirst
.
public int remainingCapacity()
size
of this deque.
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 java.util.concurrent.BlockingQueue<E>
public int drainTo(java.util.Collection<? super E> c)
drainTo
in interface java.util.concurrent.BlockingQueue<E>
java.lang.UnsupportedOperationException
java.lang.ClassCastException
java.lang.NullPointerException
java.lang.IllegalArgumentException
public int drainTo(java.util.Collection<? super E> c, int maxElements)
drainTo
in interface java.util.concurrent.BlockingQueue<E>
java.lang.UnsupportedOperationException
java.lang.ClassCastException
java.lang.NullPointerException
java.lang.IllegalArgumentException
public void push(E e)
BlockingDeque
This method is equivalent to addFirst
.
push
in interface BlockingDeque<E>
push
in interface Deque<E>
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 E pop()
Deque
This method is equivalent to Deque.removeFirst()
.
public boolean remove(java.lang.Object o)
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
.
remove
in interface BlockingDeque<E>
remove
in interface Deque<E>
remove
in interface java.util.Collection<E>
remove
in interface java.util.concurrent.BlockingQueue<E>
remove
in class java.util.AbstractCollection<E>
o
- element to be removed from this deque, if presenttrue
if this deque changed as a result of the callpublic int size()
public boolean contains(java.lang.Object o)
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)
.contains
in interface BlockingDeque<E>
contains
in interface Deque<E>
contains
in interface java.util.Collection<E>
contains
in interface java.util.concurrent.BlockingQueue<E>
contains
in class java.util.AbstractCollection<E>
o
- object to be checked for containment in this dequetrue
if this deque contains the specified elementpublic 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.
public <T> T[] toArray(T[] 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<E>
toArray
in class java.util.AbstractCollection<E>
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<E>
public void clear()
public java.util.Iterator<E> iterator()
The returned iterator is a "weakly consistent" iterator that
will never throw 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<E>
iterator
in interface Deque<E>
iterator
in interface java.lang.Iterable<E>
iterator
in interface java.util.Collection<E>
iterator
in class java.util.AbstractCollection<E>
public java.util.Iterator<E> descendingIterator()
The returned iterator is a "weakly consistent" iterator that
will never throw 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<E>