| java.lang.Object | |||
| ↳ | java.util.AbstractCollection<E> | ||
| ↳ | java.util.AbstractQueue<E> | ||
| ↳ | java.util.concurrent.DelayQueue<E extends java.util.concurrent.Delayed> | ||
An unbounded blocking queue of
Delayed elements, in which an element can only be taken
when its delay has expired. The head of the queue is that
Delayed element whose delay expired furthest in the
past. If no delay has expired there is no head and poll
will return null. Expiration occurs when an element's
getDelay(TimeUnit.NANOSECONDS) method returns a value less
than or equal to zero. Even though unexpired elements cannot be
removed using take or poll, they are otherwise
treated as normal elements. For example, the size method
returns the count of both expired and unexpired elements.
This queue does not permit null elements.
This class and its iterator implement all of the
optional methods of the Collection and Iterator interfaces. The Iterator provided in method iterator() is not guaranteed to traverse the elements of
the DelayQueue in any particular order.
| Public Constructors | |||||||||||
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Creates a new DelayQueue that is initially empty.
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Creates a DelayQueue initially containing the elements of the
given collection of
Delayed instances. | |||||||||||
| Public Methods | |||||||||||
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Inserts the specified element into this delay queue.
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Atomically removes all of the elements from this delay queue.
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Removes at most the given number of available elements from
this queue and adds them to the given collection.
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Removes all available elements from this queue and adds them
to the given collection.
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Returns an iterator over all the elements (both expired and
unexpired) in this queue.
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Inserts the specified element into this delay queue.
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Inserts the specified element into this delay queue.
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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 has no elements with an expired delay.
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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.
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Inserts the specified element into this delay queue.
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Always returns Integer.MAX_VALUE because
a DelayQueue is not capacity constrained.
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Removes a single instance of the specified element from this
queue, if it is present, whether or not it has expired.
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Returns a count of how many objects this
Collection contains. | |||||||||||
Retrieves and removes the head of this queue, waiting if necessary
until an element with an expired delay is available on this queue.
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Returns an array containing all of the elements in this queue; the
runtime type of the returned array is that of the specified array.
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Returns an array containing all of the elements in this queue.
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[Expand]
Inherited Methods | |||||||||||
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From class
java.util.AbstractQueue
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From class
java.util.AbstractCollection
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From class
java.lang.Object
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From interface
java.lang.Iterable
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From interface
java.util.Collection
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From interface
java.util.Queue
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From interface
java.util.concurrent.BlockingQueue
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Creates a DelayQueue initially containing the elements of the
given collection of Delayed instances.
| c | the collection of elements to initially contain |
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| NullPointerException | if the specified collection or any of its elements are null |
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Inserts the specified element into this delay queue.
| e | the element to add |
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add(E))| NullPointerException | if the specified element is null |
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Atomically removes all of the elements from this delay queue. The queue will be empty after this call returns. Elements with an unexpired delay are not waited for; they are simply discarded from the queue.
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.
| c | the collection to transfer elements into |
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| maxElements | the maximum number of elements to transfer |
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.
| c | the collection to transfer elements into |
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Returns an iterator over all the elements (both expired and unexpired) in this queue. The iterator does not return the elements in any particular order.
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.
Inserts the specified element into this delay queue.
| e | the element to add |
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| NullPointerException | if the specified element is null |
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Inserts the specified element into this delay queue. As the queue is unbounded this method will never block.
| e | the element to add |
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| timeout | This parameter is ignored as the method never blocks |
| unit | This parameter is ignored as the method never blocks |
| NullPointerException |
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Retrieves, but does not remove, the head of this queue, or returns null if this queue is empty. Unlike poll, if no expired elements are available in the queue, this method returns the element that will expire next, if one exists.
Retrieves and removes the head of this queue, or returns null if this queue has no elements with an expired delay.
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.
| timeout | how long to wait before giving up, in units of unit |
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| unit | a TimeUnit determining how to interpret the timeout parameter |
| InterruptedException |
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Inserts the specified element into this delay queue. As the queue is unbounded this method will never block.
| e | the element to add |
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| NullPointerException |
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Always returns Integer.MAX_VALUE because a DelayQueue is not capacity constrained.
Removes a single instance of the specified element from this queue, if it is present, whether or not it has expired.
| o | the object to remove. |
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true if this Collection is modified, false
otherwise.Returns a count of how many objects this Collection contains.
In this class this method is declared abstract and has to be implemented
by concrete Collection implementations.
Collection contains, or Integer.MAX_VALUE
if there are more than Integer.MAX_VALUE elements in this
Collection.
Retrieves and removes the head of this queue, waiting if necessary until an element with an expired delay is available on this queue.
| InterruptedException |
|---|
Returns an array containing all of the elements in this queue; the runtime type of the returned array is that of the specified array. The returned array elements are in no particular order. 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.
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().| 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 |
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| ArrayStoreException | if the runtime type of the specified array is not a supertype of the runtime type of every element in this queue |
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| NullPointerException | if the specified array is null |
Returns an array containing all of the elements in this queue. The returned array elements are in no particular order.
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.