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.
This queue does not permit null elements.
This class implements all of the optional methods
of the Collection and Iterator interfaces.
Summary
Public Constructors
Public Methods
add,
addAll,
clear,
contains,
containsAll,
isEmpty,
iterator,
remove,
removeAll,
retainAll,
size,
toArray,
toArray,
toString
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait
add,
addAll,
clear,
contains,
containsAll,
equals,
hashCode,
isEmpty,
iterator,
remove,
removeAll,
retainAll,
size,
toArray,
toArray
Methods inherited
from interface
java.util.Queue
Details
Public Constructors
public
DelayQueue()
Creates a new DelayQueue that is initially empty.
public
DelayQueue(Collection<? extends E> c)
Creates a
DelayQueue initially containing the elements of the
given collection of
Delayed instances.
Public Methods
public
boolean
add(E o)
Adds the specified element to this queue.
Returns
- true (as per the general contract of
Collection.add).
public
void
clear()
Atomically removes all of the elements from this delay queue.
The queue will be empty after this call returns.
public
int
drainTo(Collection<? super E> c, int maxElements)
Removes at most the given number of available elements from
this queue and adds them into 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.
public
int
drainTo(Collection<? super E> c)
Removes all available elements from this queue and adds them
into 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.
public
Iterator<E>
iterator()
Returns an iterator over the elements in this queue. The iterator
does not return the elements in any particular order. The
returned iterator is a thread-safe "fast-fail" iterator that will
throw
ConcurrentModificationException
upon detected interference.
Returns
- an iterator over the elements in this queue.
public
boolean
offer(E o, long timeout, TimeUnit unit)
Inserts the specified element into this delay queue. As the queue is
unbounded this method will never block.
Parameters
o
| the element to add |
timeout
| This parameter is ignored as the method never blocks |
unit
| This parameter is ignored as the method never blocks |
public
boolean
offer(E o)
Inserts the specified element into this delay queue.
public
E
peek()
Gets but not removes the element in the head of the queue, or throws
exception if there is no element in the queue.
public
E
poll(long time, TimeUnit unit)
Retrieves and removes the head of this queue, waiting
if necessary up to the specified wait time if no elements are
present on this queue.
public
E
poll()
Gets and removes the element in the head of the queue, or returns null if
there is no element in the queue.
public
void
put(E o)
Adds the specified element to this delay queue. As the queue is
unbounded this method will never block.
public
int
remainingCapacity()
Always returns
Integer.MAX_VALUE because
a
DelayQueue is not capacity constrained.
public
boolean
remove(Object o)
Removes the first occurrence of the specified object from this
Collection. This operation traverses over the collection, looking
for the specified object. Once the object is found, the object will
be removed from the collection using the iterator's remove method.
This collection will throw an UnsupportedOperationException if the
iterator returned does not implement remove method, and the specified
object is in this collection.
Returns
- true if this Collection is modified, false otherwise
public
int
size()
Returns the number of elements in this Collection.
Returns
- the number of elements in this Collection
public
E
take()
Retrieves and removes the head of this queue, waiting
if no elements are present on this queue.
public
T[]
toArray(T[] array)
Returns an array containing all elements contained in this Collection. If
the specified array is large enough to hold the elements, the specified
array is used, otherwise an array of the same type is created. If the
specified array is used and is larger than this Collection, the array
element following the collection elements is set to null.
Returns
- an array of the elements from this Collection
public
Object[]
toArray()
Returns a new array containing all elements contained in this Collection.
All the elements in the array will not be referenced by the collection.
The elements in the returned array will be sorted to the same order as
those returned by the iterator of this collection itself if the collection
guarantees the order.
Returns
- an array of the elements from this Collection