803 

   804     /**

   805      * Creates a lazy concatenated {@code IntStream} whose elements are all the

   806      * elements of a first {@code IntStream} succeeded by all the elements of the

   807      * second {@code IntStream}. The resulting stream is ordered if both

   808      * of the input streams are ordered, and parallel if either of the input

   809      * streams is parallel.

   810      *

   811      * @param a the first stream

   812      * @param b the second stream to concatenate on to end of the first stream

   813      * @return the concatenation of the two streams

   814      */

   815     public static IntStream concat(IntStream a, IntStream b) {

   816         Objects.requireNonNull(a);

   817         Objects.requireNonNull(b);

   818 

   819         Spliterator.OfInt split = new Streams.ConcatSpliterator.OfInt(

   820                 a.spliterator(), b.spliterator());

   821         return (a.isParallel() || b.isParallel())

   822                ? StreamSupport.intParallelStream(split)

   823                : StreamSupport.intStream(split);

   824     }