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From: Eric Sosman <esosman@ieee-dot-org.invalid>
Newsgroups: comp.lang.java.programmer
Subject: Re: hashCode
Date: Sun, 12 Aug 2012 13:59:07 -0400
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On 8/12/2012 12:40 PM, Patricia Shanahan wrote:
>[...]
> I think there are two reasonably usable ways of handling this issue. One
> is the current arrangement, in which every class has a hashCode that is
> expected to be usable for selecting a hash table bucket.
>
> Keeping hashCode as an Object method but making it useless for bucket
> selection unless overridden would not be a good alternative.
>
> A more reasonable alternative would be to have hashCode as the only
> member of a HashKey interface that would be implemented by every class
> whose objects are intended to be suitable for use as has keys. Those
> objects that have a hashCode would still have to have a usable one, but
> some classes would not implement HashKey and not have a hashCode at all.

     Ugh.  So if J. Random Programmer is too lazy or unimaginative to
write hashCode(), that means I can't use his class as a HashMap key,
or even put instances in a HashSet?  Ugh, again.

     (And, no: I don't think a HashCalculator interface along the lines
of Comparable would save the day.)

-- 
Eric Sosman
esosman@ieee-dot-org.invalid