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java.lang.Object
java.util.AbstractCollection<E>
java.util.AbstractQueue<E>
java.util.concurrent.DelayQueue<E,extends,Delayed>
Collection
and Iterator
interfaces.
This class is a member of the
../../../../technotes/guides/collections/index.html">
Java Collections Framework.
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Methods inherited from class java.util.AbstractCollection<E> | |
T[] toArray , add , addAll , clear , contains , containsAll , isEmpty , iterator , remove , removeAll , retainAll , size , toArray , toString |
Methods inherited from class java.lang.Object | |
clone , equals , extends Object> getClass , finalize , hashCode , notify , notifyAll , toString , wait , wait , wait |
public DelayQueue(E> c)
Creates a DelayQueue initially containing the elements of the given collection ofDelayed
instances.
- Parameters:
c
- the collection of elements to initially contain
- Throws:
NullPointerException
- if the specified collection or any of its elements are null
publicT[] toArray(T[] 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. 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 thetoArray()
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().
- Specified by:
- T[] toArray in interface Collection<E>
- Overrides:
- T[] toArray in interface AbstractCollection<E>
- 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 queueNullPointerException
- if the specified array is null
public boolean add(E e)
Inserts the specified element into this delay queue.
- Specified by:
- add in interface BlockingQueue<E>
- add in interface Queue<E>
- add in interface Collection<E>
- Overrides:
- add in interface AbstractQueue<E>
- Parameters:
e
- the element to add
- Returns:
- true (as specified by
Collection.add(E)
)
- Throws:
NullPointerException
- if the specified element is null
public void clear()
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.
- Specified by:
- clear in interface Collection<E>
- Overrides:
- clear in interface AbstractQueue<E>
public Iteratoriterator()
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 throwConcurrentModificationException
, 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.
- Specified by:
- iterator in interface Collection<E>
- iterator in interface Iterable<E>
- Overrides:
- iterator in interface AbstractCollection<E>
- Returns:
- an iterator over the elements in this queue
public boolean offer(E e)
Inserts the specified element into this delay queue.
- Specified by:
- offer in interface BlockingQueue<E>
- offer in interface Queue<E>
- Parameters:
e
- the element to add
- Returns:
- true
- Throws:
NullPointerException
- if the specified element is null
public boolean offer(E e, long timeout, TimeUnit unit)
Inserts the specified element into this delay queue. As the queue is unbounded this method will never block.
- Specified by:
- offer in interface BlockingQueue<E>
- Parameters:
e
- the element to addtimeout
- This parameter is ignored as the method never blocksunit
- This parameter is ignored as the method never blocks
- Returns:
- true
- Throws:
NullPointerException
-
public E peek()
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.
- Returns:
- the head of this queue, or null if this queue is empty.
public E poll()
Retrieves and removes the head of this queue, or returns null if this queue has no elements with an expired delay.
- Returns:
- the head of this queue, or null if this queue has no elements with an expired delay
public E poll(long timeout, TimeUnit unit) throws InterruptedException
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.
- Specified by:
- poll in interface BlockingQueue<E>
- Returns:
- the head of this queue, or null if the specified waiting time elapses before an element with an expired delay becomes available
- Throws:
InterruptedException
-
public void put(E e)
Inserts the specified element into this delay queue. As the queue is unbounded this method will never block.
- Specified by:
- put in interface BlockingQueue<E>
- Parameters:
e
- the element to add
- Throws:
NullPointerException
-
public int remainingCapacity()
Always returns Integer.MAX_VALUE because a DelayQueue is not capacity constrained.
- Specified by:
- remainingCapacity in interface BlockingQueue<E>
- Returns:
- Integer.MAX_VALUE
public boolean remove(Object o)
Removes a single instance of the specified element from this queue, if it is present, whether or not it has expired.
- Specified by:
- remove in interface BlockingQueue<E>
- remove in interface Collection<E>
- Overrides:
- remove in interface AbstractCollection<E>
public int size()
- Specified by:
- size in interface Collection<E>
- Overrides:
- size in interface AbstractCollection<E>
public E take() throws InterruptedException
Retrieves and removes the head of this queue, waiting if necessary until an element with an expired delay is available on this queue.
- Specified by:
- take in interface BlockingQueue<E>
- Returns:
- the head of this queue
- Throws:
InterruptedException
-
public Object[] toArray()
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.
- Specified by:
- toArray in interface Collection<E>
- Overrides:
- toArray in interface AbstractCollection<E>
- Returns:
- an array containing all of the elements in this queue
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