Package org.apache.commons.collections4.queue

# Class TransformedQueue<E>

java.lang.Object
org.apache.commons.collections4.collection.AbstractCollectionDecorator<E>
org.apache.commons.collections4.collection.TransformedCollection<E>
org.apache.commons.collections4.queue.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

- ## Field Summary

  ### Fields inherited from class org.apache.commons.collections4.collection.TransformedCollection

  `transformer`

- ## Constructor Summary

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

- ## Method Summary

  Modifier and Type
  Method
  Description
  `E`
  `element()`
  `protected Queue<E>`
  `getQueue()`
  Gets the decorated queue.
  `boolean`
  `offer(E obj)`
  `E`
  `peek()`
  `E`
  `poll()`
  `E`
  `remove()`
  `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.
  `static <E> TransformedQueue<E>`
  `transformingQueue(Queue<E> queue, Transformer<? super E,? extends E> transformer)`
  Factory method to create a transforming queue.

  ### Methods inherited from class org.apache.commons.collections4.collection.TransformedCollection

  `add, addAll, transform, transform, transformedCollection, transformingCollection`

  ### Methods inherited from class org.apache.commons.collections4.collection.AbstractCollectionDecorator

  `clear, contains, containsAll, decorated, isEmpty, iterator, remove, removeAll, removeIf, retainAll, setCollection, size, toArray, toArray, toString`

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

  ### Methods inherited from interface java.util.Collection

  `addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, parallelStream, remove, removeAll, removeIf, retainAll, size, spliterator, stream, toArray, toArray`

  ### Methods inherited from interface java.lang.Iterable

  `forEach`

  ### Methods inherited from interface java.util.Queue

  `add`

- ## Constructor Details

  - ### 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 Details

  - ### 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

  - ### 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

  - ### element

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

  - ### 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>`

  - ### peek

    public E peek()
    Specified by:
      `peek` 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>`