@GwtCompatible public abstract class ForwardingQueue<E> extends ForwardingCollection<E> implements Queue<E>
Warning: The methods of ForwardingQueue forward indiscriminately to the
methods of the delegate. For example, overriding ForwardingCollection.add(E) alone will not change the
behavior of offer(E) which can lead to unexpected behavior. In this case, you should
override offer as well, either providing your own implementation, or delegating to the
provided standardOffer method.
default method warning: This class does not forward calls to default methods. Instead, it inherits their default implementations. When those implementations
invoke methods, they invoke methods on the ForwardingQueue.
The standard methods are not guaranteed to be thread-safe, even when all of the
methods that they depend on are thread-safe.
| Modifier | Constructor and Description |
|---|---|
protected |
ForwardingQueue()
Constructor for use by subclasses.
|
| Modifier and Type | Method and Description |
|---|---|
protected abstract Queue<E> |
delegate()
Returns the backing delegate instance that methods are forwarded to.
|
E |
element()
Retrieves, but does not remove, the head of this queue.
|
boolean |
offer(E o)
Inserts the specified element into this queue if it is possible to do
so immediately without violating capacity restrictions.
|
E |
peek()
Retrieves, but does not remove, the head of this queue,
or returns
null if this queue is empty. |
E |
poll()
Retrieves and removes the head of this queue,
or returns
null if this queue is empty. |
E |
remove()
Retrieves and removes the head of this queue.
|
protected boolean |
standardOffer(E e)
A sensible definition of
offer(E) in terms of ForwardingCollection.add(E). |
protected E |
standardPeek()
|
protected E |
standardPoll()
|
add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, standardAddAll, standardClear, standardContains, standardContainsAll, standardIsEmpty, standardRemove, standardRemoveAll, standardRetainAll, standardToArray, standardToArray, standardToString, toArray, toArraytoStringclone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitaddAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, parallelStream, remove, removeAll, removeIf, retainAll, size, spliterator, stream, toArray, toArrayprotected ForwardingQueue()
protected abstract Queue<E> delegate()
ForwardingObjectForwardingSet.delegate(). Concrete subclasses override this method to supply the
instance being decorated.delegate in class ForwardingCollection<E>@CanIgnoreReturnValue public boolean offer(E o)
java.util.QueueQueue.add(E), which can fail to insert an element only
by throwing an exception.@CanIgnoreReturnValue public E poll()
java.util.Queuenull if this queue is empty.@CanIgnoreReturnValue public E remove()
java.util.Queuepoll only in that it throws an exception if this
queue is empty.public E peek()
java.util.Queuenull if this queue is empty.public E element()
java.util.Queuepeek only in that it throws an exception
if this queue is empty.protected boolean standardOffer(E e)
offer(E) in terms of ForwardingCollection.add(E). If you override ForwardingCollection.add(E),
you may wish to override offer(E) to forward to this implementation.protected E standardPeek()
peek() in terms of element(). If you override element(), you may wish to override peek() to forward to this implementation.Copyright © 2010–2020. All rights reserved.