Hello! When reviewing 8079136 I noticed that ArrayList.subList().spliterator() is not late-binding:
List<Integer> list = new ArrayList<>(Arrays.asList(1,2,3,4)).subList(0, 3); Stream<Integer> s = list.stream(); list.add(5); s.findFirst(); --> Exception in thread "main" java.util.ConcurrentModificationException This works correctly for other list implementation (for example, replacing ArrayList with LinkedList makes this code working). As Collection.spliterator() spec says: > In order to preserve expected laziness behavior for the stream() and > parallelStream() methods, spliterators should either have the > characteristic of IMMUTABLE or CONCURRENT, or be late-binding. If > none of these is practical, the overriding class should describe the > spliterator's documented policy of binding and structural > interference, and should override the stream() and parallelStream() > methods to create streams using a Supplier of the spliterator None of these is true for ArrayList.subList().spliterator(): it's not IMMUTABLE, not CONCURRENT, not late-binding, the binding policy is not documented and stream()/parallelStream() methods are not overridden. Is this an issue? Actually to my opinion late-binding spliterator behavior is a mistake. Nobody cares about it as nobody modifies the source between stream creation and terminal operation call. On the other hand, this requirement adds implementation complexity and I already found the second late-binding problem in existing code (the first one was with Pattern.splitAsStream). Also it's not documented that Stream.concat may bind the late-binding source, but nobody cares anyways. Life would be easier without late-binding spliterators. With best regards, Tagir Valeev.
