RFR: 7057785 : (xs) Add note to hashCode() that support for self referential is optional
Mike Duigou
mike.duigou at oracle.com
Mon Sep 30 21:29:03 UTC 2013
Ping!
(still need a Reviewer on this issue)
Mike
On Sep 16 2013, at 15:49 , Mike Duigou wrote:
> Ping!
>
> (still need a reviewer on this)
>
> Mike
>
> On Sep 4 2013, at 11:44 , Mike Duigou wrote:
>
>> Hello all;
>>
>> I have updated the proposed changeset for this issue. I have moved the note to the interface documentation for Collection and Map and made it more general:
>>
>>> Some collection operations which perform recursive traversal of the
>>> collection may fail with an exception for self-referential instances where
>>> the collection directly or indirectly contains itself. This includes the
>>> {@code clone()}, {@code equals()}, {@code hashCode()} and {@code toString()}
>>> methods. Implementations may optionally handle the self-referential scenario,
>>> however most current implementations do not do so.
>>
>> The webrev is at:
>>
>> http://cr.openjdk.java.net/~mduigou/JDK-7057785/1/webrev/
>>
>> Mike
>>
>> On Aug 27 2013, at 19:06 , Mike Duigou wrote:
>>
>>> Hello all;
>>>
>>> Fairly frequently it is reported that various Collection/Map implementations of hashCode() fail when the instance directly or indirectly contains itself. For a variety of reasons, mostly performance and resource related, most implementations choose not to support calculation of hash codes for self-referential collections. This is not likely to change. So to reduce confusion and "bug" reports I am proposing a non-normative @apiNote be added to Collection and HashMap. The text of the proposed note is:
>>>
>>>> Support for calculation of hash code by self referential {Collection|Map}s (they either directly or indirectly contain themselves) is optional. Few Collection implementations support calculation of hash code for self referential instances.
>>>
>>>
>>> http://cr.openjdk.java.net/~mduigou/JDK-7057785/0/webrev/
>>>
>>> Cheers,
>>>
>>> Mike
>>
>
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