org.apache.commons.collections4.iterators

## Class LoopingIterator<E>

- java.lang.Object
- - org.apache.commons.collections4.iterators.LoopingIterator<E>

- All Implemented Interfaces:
    Iterator<E>, ResettableIterator<E>

      public class LoopingIterator<E>
      extends Object
      implements ResettableIterator<E>

  An Iterator that restarts when it reaches the end.

  The iterator will loop continuously around the provided elements, unless there are no elements in the collection to begin with, or all the elements have been `removed`.

  Concurrent modifications are not directly supported, and for most collection implementations will throw a ConcurrentModificationException.

  Since:
    3.0

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `LoopingIterator(Collection<? extends E> coll)` Constructor that wraps a collection.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `boolean` | `hasNext()` Has the iterator any more elements.
    `E` | `next()` Returns the next object in the collection.
    `void` | `remove()` Removes the previously retrieved item from the underlying collection.
    `void` | `reset()` Resets the iterator back to the start of the collection.
    `int` | `size()` Gets the size of the collection underlying the iterator.

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

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

    - ### Methods inherited from interface java.util.Iterator

      `forEachRemaining`

- - ### Constructor Detail

    - #### LoopingIterator

          public LoopingIterator(Collection<? extends E> coll)

      Constructor that wraps a collection.

      There is no way to reset an Iterator instance without recreating it from the original source, so the Collection must be passed in.

      Parameters:
        `coll` - the collection to wrap
      Throws:
        `NullPointerException` - if the collection is null

  - ### Method Detail

    - #### hasNext

          public boolean hasNext()

      Has the iterator any more elements.

      Returns false only if the collection originally had zero elements, or all the elements have been `removed`.

      Specified by:
        `hasNext` in interface `Iterator<E>`
      Returns:
        `true` if there are more elements

    - #### next

          public E next()

      Returns the next object in the collection.

      If at the end of the collection, return the first element.

      Specified by:
        `next` in interface `Iterator<E>`
      Returns:
        the next object
      Throws:
        `NoSuchElementException` - if there are no elements at all. Use `hasNext()` to avoid this error.

    - #### remove

          public void remove()

      Removes the previously retrieved item from the underlying collection.

      This feature is only supported if the underlying collection's `iterator` method returns an implementation that supports it.

      This method can only be called after at least one `next()` method call. After a removal, the remove method may not be called again until another next has been performed. If the `reset()` is called, then remove may not be called until `next()` is called again.

      Specified by:
        `remove` in interface `Iterator<E>`

    - #### reset

          public void reset()

      Resets the iterator back to the start of the collection.
      Specified by:
        `reset` in interface `ResettableIterator<E>`

    - #### size

          public int size()

      Gets the size of the collection underlying the iterator.
      Returns:
        the current collection size

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