java.lang.Object | ||
↳ | java.util.AbstractCollection<E> | |
↳ | java.util.AbstractQueue<E> |
Known Direct Subclasses
ArrayBlockingQueue<E>,
ConcurrentLinkedQueue<E>,
DelayQueue<E extends Delayed>,
LinkedBlockingDeque<E>,
LinkedBlockingQueue<E>,
PriorityBlockingQueue<E>,
PriorityQueue<E>,
SynchronousQueue<E>
|
This class provides skeletal implementations of some Queue
operations. The implementations in this class are appropriate when
the base implementation does not allow null
elements. Methods add
, remove
, and
element
are based on offer
, poll
, and peek
, respectively, but throw
exceptions instead of indicating failure via false or
null returns.
A Queue implementation that extends this class must
minimally define a method offer(E)
which does not permit
insertion of null elements, along with methods peek()
, poll()
, size()
, and
iterator()
. Typically, additional methods will be
overridden as well. If these requirements cannot be met, consider
instead subclassing AbstractCollection
.
Protected Constructors | |||||||||||
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Constructor for use by subclasses.
|
Public Methods | |||||||||||
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Inserts the specified element into this queue if it is possible to do so
immediately without violating capacity restrictions, returning
true upon success and throwing an IllegalStateException
if no space is currently available.
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Adds all of the elements in the specified collection to this
queue.
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Removes all of the elements from this queue.
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Retrieves, but does not remove, the head of this queue.
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Retrieves and removes the head of this queue.
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[Expand]
Inherited Methods | |||||||||||
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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
|
Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions, returning true upon success and throwing an IllegalStateException if no space is currently available.
This implementation returns true if offer succeeds, else throws an IllegalStateException.
e | the element to add |
---|
add(E)
)IllegalStateException | if the element cannot be added at this time due to capacity restrictions |
---|---|
ClassCastException | if the class of the specified element prevents it from being added to this queue |
NullPointerException | if the specified element is null and this queue does not permit null elements |
IllegalArgumentException | if some property of this element prevents it from being added to this queue |
Adds all of the elements in the specified collection to this queue. Attempts to addAll of 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.
This implementation iterates over the specified collection, and adds each element returned by the iterator to this queue, in turn. A runtime exception encountered while trying to add an element (including, in particular, a null element) may result in only some of the elements having been successfully added when the associated exception is thrown.
c | collection containing elements to be added to this queue |
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ClassCastException | if the class of an element of the specified collection prevents it from being added to this queue |
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NullPointerException | if the specified collection contains a null element and this queue does not permit null elements, or if the specified collection is null |
IllegalArgumentException | if some property of an element of the specified collection prevents it from being added to this queue, or if the specified collection is this queue |
IllegalStateException | if not all the elements can be added at this time due to insertion restrictions |
Removes all of the elements from this queue. The queue will be empty after this call returns.
This implementation repeatedly invokes poll
until it
returns null.
Retrieves, but does not remove, the head of this queue. This method
differs from peek
only in that it throws an exception if
this queue is empty.
This implementation returns the result of peek unless the queue is empty.
NoSuchElementException | if this queue is empty |
---|
Retrieves and removes the head of this queue. This method differs
from poll
only in that it throws an exception if this
queue is empty.
This implementation returns the result of poll unless the queue is empty.
NoSuchElementException | if this queue is empty |
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