Class ForwardingQueue<E>

java.lang.Object
com.google.common.collect.ForwardingObject
com.google.common.collect.ForwardingCollection<E>
com.google.common.collect.ForwardingQueue<E>
All Implemented Interfaces:
Iterable<E>, Collection<E>, Queue<E>
Direct Known Subclasses:
EvictingQueue, ForwardingBlockingQueue, ForwardingDeque
@GwtCompatible public abstract class ForwardingQueue<E> extends ForwardingCollection<E> implements Queue<E>
A queue which forwards all its method calls to another queue. Subclasses should override one or more methods to modify the behavior of the backing queue as desired per the decorator pattern.

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.

Since:
2.0

  • Constructor Details

    • ForwardingQueue

      protected ForwardingQueue()
      Constructor for use by subclasses.

  • Method Details

    • delegate

      protected abstract Queue<E> delegate()
      Description copied from class: ForwardingObject
      Returns the backing delegate instance that methods are forwarded to. Abstract subclasses generally override this method with an abstract method that has a more specific return type, such as ForwardingSet.delegate(). Concrete subclasses override this method to supply the instance being decorated.
      Specified by:
      delegate in class ForwardingCollection<E>

    • offer

      public boolean offer(E o)
      Specified by:
      offer in interface Queue<E>

    • poll

      public E poll()
      Specified by:
      poll in interface Queue<E>

    • remove

      public E remove()
      Specified by:
      remove in interface Queue<E>

    • peek

      public E peek()
      Specified by:
      peek in interface Queue<E>

    • element

      public E element()
      Specified by:
      element in interface Queue<E>

    • standardOffer

      protected boolean standardOffer(E e)
      A sensible definition of 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.
      Since:
      7.0

    • standardPeek

      protected E standardPeek()
      A sensible definition of peek() in terms of element(). If you override element(), you may wish to override peek() to forward to this implementation.
      Since:
      7.0

    • standardPoll

      protected E standardPoll()
      A sensible definition of poll() in terms of remove(). If you override remove(), you may wish to override poll() to forward to this implementation.
      Since:
      7.0