edu.emory.mathcs.backport.java.util.concurrent
public class DelayQueue extends AbstractQueue implements BlockingQueue
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 |
---|
DelayQueue()
Creates a new DelayQueue that is initially empty.
|
DelayQueue(java.util.Collection c)
Creates a DelayQueue initially containing the elements of the
given collection of
Delayed instances. |
Modifier and Type | Method and Description |
---|---|
boolean |
add(java.lang.Object e)
Inserts the specified element into this delay queue.
|
void |
clear()
Atomically removes all of the elements from this delay queue.
|
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.util.Iterator |
iterator()
Returns an iterator over all the elements (both expired and
unexpired) in this queue.
|
boolean |
offer(java.lang.Object e)
Inserts the specified element into this delay queue.
|
boolean |
offer(java.lang.Object e,
long timeout,
TimeUnit unit)
Inserts the specified element into this delay queue.
|
java.lang.Object |
peek()
Retrieves, but does not remove, the head of this queue, or
returns null if this queue is empty.
|
java.lang.Object |
poll()
Retrieves and removes the head of this queue, or returns null
if this queue has no elements with an expired delay.
|
java.lang.Object |
poll(long timeout,
TimeUnit unit)
Retrieves and removes the head of this queue, waiting if necessary
until an element with an expired delay is available on this queue,
or the specified wait time expires.
|
void |
put(java.lang.Object e)
Inserts the specified element into this delay queue.
|
int |
remainingCapacity()
Always returns Integer.MAX_VALUE because
a DelayQueue is not capacity constrained.
|
boolean |
remove(java.lang.Object o)
Removes a single instance of the specified element from this
queue, if it is present, whether or not it has expired.
|
int |
size() |
java.lang.Object |
take()
Retrieves and removes the head of this queue, waiting if necessary
until an element with an expired delay is available on this queue.
|
java.lang.Object[] |
toArray()
Returns an array containing all of the elements in this queue.
|
java.lang.Object[] |
toArray(java.lang.Object[] a)
Returns an array containing all of the elements in this queue; the
runtime type of the returned array is that of the specified array.
|
addAll, element, remove
contains, containsAll, isEmpty, removeAll, retainAll, toString
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
contains
public DelayQueue()
public DelayQueue(java.util.Collection c)
Delayed
instances.c
- the collection of elements to initially containjava.lang.NullPointerException
- if the specified collection or any
of its elements are nullpublic boolean add(java.lang.Object e)
add
in interface BlockingQueue
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.NullPointerException
- if the specified element is nullpublic boolean offer(java.lang.Object e)
offer
in interface BlockingQueue
offer
in interface Queue
e
- the element to addjava.lang.NullPointerException
- if the specified element is nullpublic void put(java.lang.Object e)
put
in interface BlockingQueue
e
- the element to addjava.lang.NullPointerException
- if the specified element is nullpublic boolean offer(java.lang.Object e, long timeout, TimeUnit unit)
offer
in interface BlockingQueue
e
- the element to addtimeout
- This parameter is ignored as the method never blocksunit
- This parameter is ignored as the method never blocksjava.lang.NullPointerException
- if the specified element is nullpublic java.lang.Object poll()
public java.lang.Object take() throws java.lang.InterruptedException
take
in interface BlockingQueue
java.lang.InterruptedException
- if interrupted while waitingpublic java.lang.Object poll(long timeout, TimeUnit unit) throws java.lang.InterruptedException
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 peek()
public int size()
size
in interface java.util.Collection
size
in class java.util.AbstractCollection
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 clear()
clear
in interface java.util.Collection
clear
in class AbstractQueue
public int remainingCapacity()
remainingCapacity
in interface BlockingQueue
public java.lang.Object[] toArray()
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.
toArray
in interface java.util.Collection
toArray
in class AbstractCollection
public java.lang.Object[] toArray(java.lang.Object[] a)
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.
The following code can be used to dump a delay queue into a newly allocated array of Delayed:
Delayed[] a = q.toArray(new Delayed[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 queue 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 queuejava.lang.NullPointerException
- if the specified array is nullpublic boolean remove(java.lang.Object o)
remove
in interface BlockingQueue
remove
in interface java.util.Collection
remove
in class java.util.AbstractCollection
o
- element to be removed from this queue, if presentpublic 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 java.lang.Iterable
iterator
in interface java.util.Collection
iterator
in class java.util.AbstractCollection