Method last

guava/src/com/google/common/collect/FluentIterable.java:529–562

Returns an {@link Optional} containing the last element in this fluent iterable. If the iterable is empty, {@code Optional.absent()} is returned. If the underlying {@code iterable} is a {@link List} with {@link java.util.RandomAccess} support, then this operation is guaranteed to be {@code O(1)}. <

()

   *     Iterables#getLast} instead.
   */
  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
  public final Optional<@NonNull E> last() {
    // Iterables#getLast was inlined here so we don't have to throw/catch a NSEE

    // TODO(kevinb): Support a concurrently modified collection?
    Iterable<E> iterable = getDelegate();
    if (iterable instanceof List) {
      List<E> list = (List<E>) iterable;
      if (list.isEmpty()) {
        return Optional.absent();
      }
      return Optional.of(list.get(list.size() - 1));
    }
    Iterator<E> iterator = iterable.iterator();
    if (!iterator.hasNext()) {
      return Optional.absent();
    }

    /*
     * TODO(kevinb): consider whether this "optimization" is worthwhile. Users with SortedSets tend
     * to know they are SortedSets and probably would not call this method.
     */
    if (iterable instanceof SortedSet) {
      SortedSet<E> sortedSet = (SortedSet<E>) iterable;
      return Optional.of(sortedSet.last());
    }

    while (true) {
      E current = iterator.next();
      if (!iterator.hasNext()) {
        return Optional.of(current);
      }
    }
  }

  /**
   * Returns a view of this fluent iterable that skips its first {@code numberToSkip} elements. If