Package org.apache.commons.collections4.iterators

Class ExtendedIterator<T>

java.lang.Object
org.apache.commons.collections4.iterators.ExtendedIterator<T>
Type Parameters:
T - The type of object returned from the iterator.
All Implemented Interfaces:
Iterator<T>, IteratorOperations<T>
public final class ExtendedIterator<T> extends Object implements IteratorOperations<T>
Extends Iterator functionality to include operations commonly found on streams (e.g. filtering, concatenating, mapping). It also provides convenience methods for common operations.
Since:
4.5.0-M3

  • Method Details

    • create

      public static <T> ExtendedIterator<T> create(Iterator<T> it)
      Create an ExtendedIterator returning the elements of it. If it is itself an ExtendedIterator, return that; otherwise wrap it.
      Type Parameters:
      T - The type of object returned from the iterator.
      Parameters:
      it - The iterator to wrap.
      Returns:
      An Extended iterator wrapping it

    • create

      public static <T> ExtendedIterator<T> create(Stream<T> stream)
      Creates an ExtendedIterator wrapped round a Stream. The extended iterator does not permit .remove().

      The stream should not be used directly. The effect of doing so is undefined.

      Type Parameters:
      T - The type of object returned from the iterator.
      Parameters:
      stream - the Stream to create an iterator from.
      Returns:
      an Extended iterator on the stream iterator.

    • createNoRemove

      public static <T> ExtendedIterator<T> createNoRemove(Iterator<T> it)
      Creates an ExtendedIterator wrapped round it, which does not permit .remove() even if it does.
      Type Parameters:
      T - The type of object returned from the iterator.
      Parameters:
      it - The Iterator to wrap.
      Returns:
      an Extended iterator on it
      Throws:
      UnsupportedOperationException - if remove() is called on the resulting iterator.

    • emptyIterator

      public static ExtendedIterator<?> emptyIterator()
      Creates an empty Extended iterator.
      Returns:
      An empty Extended iterator.

    • flatten

      public static <T> ExtendedIterator<T> flatten(Iterator<Iterator<T>> iterators)
      Flattens an iterator of iterators into an Iterator over the next level values. Similar to list splicing in lisp.
      Type Parameters:
      T - The type of object returned from the iterator.
      Parameters:
      iterators - An iterator of iterators.
      Returns:
      An iterator over the logical concatenation of the inner iterators.

    • andThen

      public <X extends T> ExtendedIterator<T> andThen(Iterator<X> other)
      Chains the other iterator to the end of this one.
      Type Parameters:
      X - The type of object returned from the other iterator.
      Parameters:
      other - the other iterator to extend this iterator with.
      Returns:
      A new iterator returning the contents of this iterator followed by the contents of other iterator.

    • filter

      public ExtendedIterator<T> filter(Predicate<T> predicate)
      Filter this iterator using a predicate. Only items for which the predicate returns true will be included in the result.
      Parameters:
      predicate - The predicate to filter the items with.
      Returns:
      An iterator filtered by the predicate.

    • forEachRemaining

      public void forEachRemaining(Consumer<? super T> action)
      Specified by:
      forEachRemaining in interface Iterator<T>

    • hasNext

      public boolean hasNext()
      Specified by:
      hasNext in interface Iterator<T>

    • map

      public <U> ExtendedIterator<U> map(Function<T,U> function)
      Map the elements of the iterator to a now type.
      Type Parameters:
      U - The object type to return.
      Parameters:
      function - The function to map elements of <T> to type <U>.
      Returns:
      An Extended iterator that returns a <U> for very <T> in the original iterator.

    • next

      public T next()
      Specified by:
      next in interface Iterator<T>

    • remove

      public void remove()
      Specified by:
      remove in interface Iterator<T>