RFR : 8016446 : (m) Add override forEach/replaceAll to HashMap, Hashtable, IdentityHashMap, WeakHashMap, TreeMap

[Paul Sandoz]

On Jun 13, 2013, at 8:42 AM, Peter Levart <peter.levart at gmail.com> wrote:

> On 06/13/2013 01:14 AM, Mike Duigou wrote:
>> On Jun 12 2013, at 15:49 , Remi Forax wrote:
>> 
>>> On 06/12/2013 11:23 PM, Mike Duigou wrote:
>>>> Hello all;
>>>> 
>>>> This patch adds optimized implementations of Map.forEach and Map.replaceAll to HashMap, Hashtable, IdentityHashMap, WeakHashMap, TreeMap
>>>> 
>>>> http://cr.openjdk.java.net/~mduigou/JDK-8016446/0/webrev/
>>>> 
>>>> The implementations traverse the map more efficiently than the default iterator implementation and sometimes avoid creation of transient Map.Entry instances. The fast-fail behaviour of the default implementation is retained.
>>>> 
>>>> Mike
>>> Hi Mike,
>>> funnily I was writing HashMap.forEach/LinkedHashMap.forEach at the same time.
>>> (you need also to override forEach in LinkedHashMap because the one you inherits from HashMap doesn't use the linked list of entries).
>> I don't think we need to offer a guarantee of ordering for the forEach but using the linked list is probably more efficient.
> 
> The javadoc for Map.forEach says differently:
> 
> default void forEach(BiConsumer  <http://download.java.net/jdk8/docs/api/java/util/function/BiConsumer.html><? superK  <http://download.java.net/jdk8/docs/api/java/util/Map.html>,? superV  <http://download.java.net/jdk8/docs/api/java/util/Map.html>> action)
> 
> Performs the given action on each entry in this map, in the order entries are returned by an entry set iterator (which may be unspecified)

Right, LinkedHashMap should preserve the encounter order on traversal, bulk or otherwise.

Note that there is a bug logged against LinkedHashMap.spliterator. It should but currently does not report ORDERED for key/value/entry Spliterators.

Paul.