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FlexDoc/Javadoc 2.0 Demo Java Doc |
Class LinkedBlockingQueue<E>
java.util.concurrent.LinkedBlockingQueue<E>
Type Parameters:
E - the type of elements held in this queue
All Implemented Interfaces:
public class LinkedBlockingQueue<E>
An optionally-bounded
blocking queue based on
linked nodes.
This queue orders elements FIFO (first-in-first-out).
The
head of the queue is that element that has been on the
queue the longest time.
The
tail of the queue is that element that has been on the
queue the shortest time. New elements
are inserted at the tail of the queue, and the queue retrieval
operations obtain elements at the head of the queue.
Linked queues typically have higher throughput than array-based queues but
less predictable performance in most concurrent applications.
The optional capacity bound constructor argument serves as a
way to prevent excessive queue expansion. The capacity, if unspecified,
is equal to Integer.MAX_VALUE. Linked nodes are
dynamically created upon each insertion unless this would bring the
queue above capacity.
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.
Since:
1.5
Author:
Doug Lea
See Also:
Constructor Summary |
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Creates a LinkedBlockingQueue with a capacity of
Integer.MAX_VALUE, initially containing the elements of the
given collection,
added in traversal order of the collection's iterator.
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Creates a LinkedBlockingQueue with the given (fixed) capacity.
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Method Summary |
void |
Atomically removes all of the elements from this queue.
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boolean |
Returns true if this queue contains the specified element.
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int |
Removes all available elements from this queue and adds them
to the given collection.
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int |
Removes at most the given number of available elements from
this queue and adds them to the given collection.
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void |
Performs the given action for each element of the Iterable
until all elements have been processed or the action throws an
exception.
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Returns an iterator over the elements in this queue in proper sequence.
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boolean |
Inserts the specified element at the tail of this queue if it is
possible to do so immediately without exceeding the queue's capacity,
returning true upon success and false if this queue
is full.
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boolean |
Inserts the specified element at the tail of this queue, waiting if
necessary up to the specified wait time for space to become available.
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Retrieves, but does not remove, the head of this queue,
or returns null if this queue is empty.
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Retrieves and removes the head of this queue,
or returns null if this queue is empty.
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Retrieves and removes the head of this queue, waiting up to the
specified wait time if necessary for an element to become available.
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void |
Inserts the specified element at the tail of this queue, waiting if
necessary for space to become available.
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int |
Returns the number of additional elements that this queue can ideally
(in the absence of memory or resource constraints) accept without
blocking.
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boolean |
Removes a single instance of the specified element from this queue,
if it is present.
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boolean |
Removes all of this collection's elements that are also contained in the
specified collection (optional operation).
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boolean |
Removes all of the elements of this collection that satisfy the given
predicate.
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boolean |
Retains only the elements in this collection that are contained in the
specified collection (optional operation).
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int |
Returns the number of elements in this queue.
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Retrieves and removes the head of this queue, waiting if necessary
until an element becomes available.
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Returns an array containing all of the elements in this queue, in
proper sequence.
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Returns an array containing all of the elements in this queue, in
proper sequence; the runtime type of the returned array is that of
the specified array.
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Returns a string representation of this collection.
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Methods inherited from class java.lang. Object |
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Methods inherited from interface java.util. Collection |
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public LinkedBlockingQueue |
() |
public LinkedBlockingQueue |
(int capacity) |
Creates a
LinkedBlockingQueue with the given (fixed) capacity.
Parameters:
capacity - the capacity of this queue
Throws:
public LinkedBlockingQueue |
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Creates a
LinkedBlockingQueue with a capacity of
Integer.MAX_VALUE, initially containing the elements of the
given collection,
added in traversal order of the collection's iterator.
Parameters:
c - the collection of elements to initially contain
Throws:
Returns the number of elements in this queue.
Specified by:
Overrides:
Returns:
the number of elements in this queue
public int remainingCapacity |
() |
Returns the number of additional elements that this queue can ideally
(in the absence of memory or resource constraints) accept without
blocking. This is always equal to the initial capacity of this queue
less the current
size of this queue.
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.
Specified by:
Returns:
the remaining capacity
Inserts the specified element at the tail of this queue, waiting if
necessary for space to become available.
Specified by:
Parameters:
e - the element to add
Throws:
public boolean offer |
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throws |
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Inserts the specified element at the tail of this queue, waiting if
necessary up to the specified wait time for space to become available.
Specified by:
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:
Inserts the specified element at the tail of this queue if it is
possible to do so immediately without exceeding the queue's capacity,
returning
true upon success and
false if this queue
is full.
When using a capacity-restricted queue, this method is generally
preferable to method
add, which can fail to
insert an element only by throwing an exception.
Specified by:
Parameters:
e - the element to add
Returns:
true if the element was added to this queue, else
false
Throws:
Retrieves and removes the head of this queue, waiting if necessary
until an element becomes available.
Specified by:
Returns:
the head of this queue
Throws:
Retrieves and removes the head of this queue, waiting up to the
specified wait time if necessary for an element to become available.
Specified by:
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 queue, or null if the
specified waiting time elapses before an element is available
Throws:
Description copied from interface:
Queue
Retrieves and removes the head of this queue,
or returns null if this queue is empty.
Specified by:
Returns:
the head of this queue, or null if this queue is empty
Description copied from interface:
Queue
Retrieves, but does not remove, the head of this queue,
or returns null if this queue is empty.
Specified by:
Returns:
the head of this queue, or null if this queue is empty
Removes a single instance of the specified element from this queue,
if it is present. More formally, removes an element
e such
that
o.equals(e), if this queue contains one or more such
elements.
Returns
true if this queue contained the specified element
(or equivalently, if this queue changed as a result of the call).
Specified by:
Overrides:
Parameters:
o - element to be removed from this queue, if present
Returns:
true if this queue changed as a result of the call
Returns
true if this queue contains the specified element.
More formally, returns
true if and only if this queue contains
at least one element
e such that
o.equals(e).
Specified by:
Overrides:
Parameters:
o - object to be checked for containment in this queue
Returns:
true if this queue contains the specified element
Returns an array containing all of the elements in this queue, in
proper sequence.
The returned array will be "safe" in that no references to it are
maintained by this queue. (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.
Specified by:
Overrides:
Returns:
an array containing all of the elements in this queue
Returns an array containing all of the elements in this queue, in
proper sequence; the runtime type of the returned array is that of
the specified array. If the queue fits in the specified array, it
is returned therein. Otherwise, a new array is allocated with the
runtime type of the specified array and the size of this queue.
If this queue fits in the specified array with room to spare
(i.e., the array has more elements than this queue), the element in
the array immediately following the end of the queue 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 queue known to contain only strings.
The following code can be used to dump the queue 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().
Specified by:
Overrides:
Type Parameters:
T - the component type of the array to contain the collection
Parameters:
a - the array into which the elements of the queue are to
be stored, if it is big enough; otherwise, a new array of the
same runtime type is allocated for this purpose
Returns:
an array containing all of the elements in this queue
Throws:
ArrayStoreException - if the runtime type of the specified array
is not a supertype of the runtime type of every element in
this queue
Returns a string representation of this collection. The string
representation consists of a list of the collection's elements in the
order they are returned by its iterator, enclosed in square brackets
(
"[]"). Adjacent elements are separated by the characters
", " (comma and space). Elements are converted to strings as
by
String.valueOf(Object).
Overrides:
Returns:
a string representation of this collection
Atomically removes all of the elements from this queue.
The queue will be empty after this call returns.
Specified by:
Overrides:
Removes all available elements from this queue and adds them
to the given collection. This operation may be more
efficient than repeatedly polling this queue. A failure
encountered while attempting to add elements to
collection c may result in elements being in neither,
either or both collections when the associated exception is
thrown. Attempts to drain a queue to itself result in
IllegalArgumentException. Further, the behavior of
this operation is undefined if the specified collection is
modified while the operation is in progress.
Specified by:
Parameters:
c - the collection to transfer elements into
Returns:
the number of elements transferred
Throws:
UnsupportedOperationException - if addition of elements
is not supported by the specified collection
ClassCastException - if the class of an element of this queue
prevents it from being added to the specified collection
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 collection
Removes at most the given number of available elements from
this queue and adds them to the given collection. A failure
encountered while attempting to add elements to
collection c may result in elements being in neither,
either or both collections when the associated exception is
thrown. Attempts to drain a queue to itself result in
IllegalArgumentException. Further, the behavior of
this operation is undefined if the specified collection is
modified while the operation is in progress.
Specified by:
Parameters:
c - the collection to transfer elements into
maxElements - the maximum number of elements to transfer
Returns:
the number of elements transferred
Throws:
UnsupportedOperationException - if addition of elements
is not supported by the specified collection
ClassCastException - if the class of an element of this queue
prevents it from being added to the specified collection
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 collection
Returns an iterator over the elements in this queue in proper sequence.
The elements will be returned in order from first (head) to last (tail).
The returned iterator is
weakly consistent.
Specified by:
Overrides:
Returns:
an iterator over the elements in this queue in proper sequence
Description copied from interface:
Iterable
Performs the given action for each element of the
Iterable
until all elements have been processed or the action throws an
exception. Actions are performed in the order of iteration, if that
order is specified. Exceptions thrown by the action are relayed to the
caller.
The behavior of this method is unspecified if the action performs
side-effects that modify the underlying source of elements, unless an
overriding class has specified a concurrent modification policy.
Specified by:
Parameters:
action - The action to be performed for each element
Throws:
Removes all of the elements of this collection that satisfy the given
predicate. Errors or runtime exceptions thrown during iteration or by
the predicate are relayed to the caller.
Specified by:
Parameters:
filter - a predicate which returns true for elements to be
removed
Returns:
true if any elements were removed
Throws:
Removes all of this collection's elements that are also contained in the
specified collection (optional operation). After this call returns,
this collection will contain no elements in common with the specified
collection.
Specified by:
Overrides:
Parameters:
c - collection containing elements to be removed from this collection
Returns:
true if this collection changed as a result of the
call
Throws:
NullPointerException - if this collection contains one or more
null elements and the specified collection does not support
null elements
(
optional),
or if the specified collection is null
See Also:
Retains only the elements in this collection that are contained in the
specified collection (optional operation). In other words, removes from
this collection all of its elements that are not contained in the
specified collection.
Specified by:
Overrides:
Parameters:
c - collection containing elements to be retained in this collection
Returns:
true if this collection changed as a result of the call
Throws:
NullPointerException - if this collection contains one or more
null elements and the specified collection does not permit null
elements
(
optional),
or if the specified collection is null
See Also:
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