Package com.google.common.collect

Class ForwardingQueue<E>

  • All Implemented Interfaces:
    java.lang.Iterable<E>, java.util.Collection<E>, java.util.Queue<E>
    Direct Known Subclasses:
    EvictingQueue, ForwardingDeque
    @GwtCompatible
public abstract class ForwardingQueue<E>
extends ForwardingCollection<E>
implements java.util.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.

    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 (imported from Google Collections Library)

    • Constructor Detail

      • ForwardingQueue

        protected ForwardingQueue()
        Constructor for use by subclasses.

    • Method Detail

      • delegate

        protected abstract java.util.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 java.util.Queue<E>

      • poll

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

      • remove

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

      • peek

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

      • element

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

      • 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