Package org.apache.commons.collections4.queue

Class TransformedQueue<E>

  • Type Parameters:
    E - the type of elements held in this queue
    All Implemented Interfaces:
    Serializable, Iterable<E>, Collection<E>, Queue<E>
    public class TransformedQueue<E>
extends TransformedCollection<E>
implements Queue<E>
    Decorates another Queue to transform objects that are added.

    The add/offer methods are affected by this class. Thus objects must be removed or searched for using their transformed form. For example, if the transformation converts Strings to Integers, you must use the Integer form to remove objects.

    Since:
    4.0
    See Also:
    Serialized Form

    • Constructor Detail

      • TransformedQueue

        protected TransformedQueue​(Queue<E> queue,
                           Transformer<? super E,​? extends E> transformer)
        Constructor that wraps (not copies).

        If there are any elements already in the queue being decorated, they are NOT transformed.

        Parameters:
        queue - the queue to decorate, must not be null
        transformer - the transformer to use for conversion, must not be null
        Throws:
        NullPointerException - if queue or transformer is null

    • Method Detail

      • transformingQueue

        public static <E> TransformedQueue<E> transformingQueue​(Queue<E> queue,
                                                        Transformer<? super E,​? extends E> transformer)
        Factory method to create a transforming queue.

        If there are any elements already in the queue being decorated, they are NOT transformed. Contrast this with transformedQueue(Queue, Transformer).

        Type Parameters:
        E - the type of the elements in the queue
        Parameters:
        queue - the queue to decorate, must not be null
        transformer - the transformer to use for conversion, must not be null
        Returns:
        a new transformed Queue
        Throws:
        NullPointerException - if queue or transformer is null

      • transformedQueue

        public static <E> TransformedQueue<E> transformedQueue​(Queue<E> queue,
                                                       Transformer<? super E,​? extends E> transformer)
        Factory method to create a transforming queue that will transform existing contents of the specified queue.

        If there are any elements already in the queue being decorated, they will be transformed by this method. Contrast this with transformingQueue(Queue, Transformer).

        Type Parameters:
        E - the type of the elements in the queue
        Parameters:
        queue - the queue to decorate, must not be null
        transformer - the transformer to use for conversion, must not be null
        Returns:
        a new transformed Queue
        Throws:
        NullPointerException - if queue or transformer is null
        Since:
        4.0

      • getQueue

        protected Queue<E> getQueue()
        Gets the decorated queue.
        Returns:
        the decorated queue

      • offer

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

      • poll

        public E poll()
        Specified by:
        poll 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>

      • remove

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