Class IteratorIterable<E>

java.lang.Object
org.apache.commons.collections4.iterators.IteratorIterable<E>
All Implemented Interfaces:
Iterable<E>
public class IteratorIterable<E> extends Object implements Iterable<E>
Adapter to make an Iterator instance appear to be an Iterable instance. The iterable can be constructed in one of two variants: single use, multiple use.

In the single use iterable case, the iterable is only usable for one iterative operation over the source iterator. Subsequent iterative operations use the same, exhausted source iterator. To create a single use iterable, construct a new IteratorIterable using a Iterator that is NOT a ResettableIterator iterator: 

  Iterator<Integer> iterator = // some non-resettable iterator
  Iterable<Integer> iterable = new IteratorIterable<Integer>(iterator);

In the multiple use iterable case, the iterable is usable for any number of iterative operations over the source iterator. Of special note, even though the iterable supports multiple iterations, it does not support concurrent iterations. To implicitly create a multiple use iterable, construct a new IteratorIterable using a ResettableIterator iterator: 

  Integer[] array = {Integer.valueOf(1),Integer.valueOf(2),Integer.valueOf(3)};
  Iterator<Integer> iterator = IteratorUtils.arrayIterator(array); // a resettable iterator
  Iterable<Integer> iterable = new IteratorIterable<Integer>(iterator);

A multiple use iterable can also be explicitly constructed using any Iterator and specifying true for the multipleUse flag: 

  Iterator<Integer> iterator = // some non-resettable iterator
  Iterable<Integer> iterable = new IteratorIterable<Integer>(iterator, true);
Since:
4.0

  • Field Details

    • iterator

      private final Iterator<? extends E> iterator
      the iterator being adapted into an iterable.

    • typeSafeIterator

      private final Iterator<E> typeSafeIterator
      the iterator parameterized as the iterator() return type.

  • Constructor Details

    • IteratorIterable

      public IteratorIterable(Iterator<? extends E> iterator)
      Constructs a new IteratorIterable that will use the given iterator.
      Parameters:
      iterator - the iterator to use.

    • IteratorIterable

      public IteratorIterable(Iterator<? extends E> iterator, boolean multipleUse)
      Constructs a new IteratorIterable that will use the given iterator.
      Parameters:
      iterator - the iterator to use.
      multipleUse - true if the new iterable can be used in multiple iterations

  • Method Details

    • createTypesafeIterator

      private static <E> Iterator<E> createTypesafeIterator(Iterator<? extends E> iterator)
      Factory method to create an Iterator from another iterator over objects of a different subtype.

    • iterator

      public Iterator<E> iterator()
      Gets the iterator wrapped by this iterable.
      Specified by:
      iterator in interface Iterable<E>
      Returns:
      the iterator