Spliterator implementations (original) (raw)

Brian Goetz brian.goetz at oracle.com
Wed Jan 2 15:58:26 PST 2013

Thanks for making this list.

There's no method for spliterator(), instead there is a method for stream() which may or may not require a spliterator. There are defaults (based on Iterator) in Collection, List, Set, and SortedSet, plus optimized implementations in ArrayList and Vector. Plus Stack inherits from Vector.

From your list, there are a few that might benefit enough from a better implementation to be worth the effort, such as Enum{Set,Map}, {Hash,Tree,LinkedHash}{Set,Map}. For most of the rest (and some of these, probably), the Iterator version is probably good enough.

On 1/2/2013 4:04 PM, Doug Lea wrote:

In the midst of trying various approaches for ConcurrentSkipList* spliterators (six or more methods supplying them!) I pasted the "All Known Implementing Classes" list from JDK7 Collection and Map javadocs and threw this list together of classes that may need spliterator implementations. (or may not, depending on defaults). As far as I know, exactly two (ArrayList and CHM) are complete and in use at the moment. In case you are interested, here it is:

For top-level classes only: j.u.c/jsr166: ArrayDeque, ArrayBlockingQueue, ConcurrentLinkedDeque, ConcurrentLinkedQueue, CopyOnWriteArraySet, DelayQueue, LinkedBlockingDeque, LinkedBlockingQueue, LinkedTransferQueue, PriorityBlockingQueue, PriorityQueue, SynchronousQueue j.u: AbstractCollection, AbstractQueue, AbstractSet, EnumSet, HashSet (delegates to HashMap.keySet), LinkedHashSet (delegates to LinkedHashMap.keySet) Stack, other jdk: BeanContextSupport (delegates to HashMap.keySet) BeanContextServicesSupport (super BeanContextSupport) JobStateReasons, (super HashSet) For both top-level and subList classes j.u.c/jsr166 CopyOnWriteArrayList, j.u: AbstractList, AbstractSequentialList, ArrayList, AttributeList, LinkedList, Stack (super Vector), Vector other jdk: RoleList (super ArrayList), RoleUnresolvedList (super ArrayList), For both top-level and subSet classes: j.u.c/jsr166 ConcurrentSkipListSet, TreeSet For keySet, values and entrySet views of: j.u.c/jsr166 ConcurrentHashMap, j.u: AbstractMap, EnumMap, HashMap, Hashtable, IdentityHashMap, LinkedHashMap, (super HashMap but cannot use same Spliterator) WeakHashMap other jdk: Attributes (delegates to HashMap) AuthProvider (super Provider) PrinterStateReasons, (super HashMap) Properties, (super Hashtable) Provider (super Properties), RenderingHints (delegates to HashMap) SimpleBindings (delegates to any Map), TabularDataSupport, (delegates to UIDefaults, (super Hashtable) For keySet, values and entrySet views, plus the same for subMap views: j.u.c/jsr166 ConcurrentSkipListMap, TreeMap,

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