Groups > comp.lang.java.programmer > #17851

Re: hashCode

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From	"Arne Vajhøj" <�� høj@1:261/38.remove-odu-this>
Subject	Re: hashCode
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  To: Lew
From: "=?UTF-8?B?QXJuZSBWYWpow7hq?=" <=?utf-8?b?qxjuzsbwywpow7hq?=@1:261/38.rem
ove-nlb-this>

  To: Lew
From: =?UTF-8?B?QXJuZSBWYWpow7hq?= <arne@vajhoej.dk>

On 8/12/2012 12:46 AM, Lew wrote:
> Arne Vajh-,j wrote:
>> The original questions were:
>>
>> #Is it always technically correct to override the hashCode function
>> #like so:
>> #
>> #    @Override
>> #    public int hashCode() {
>> #        return 1;
>> #    }
>>
>> For which the answer is YES. Per documentation.
>>
>> But with really poor performance in many relevant cases.
>>
>> #Would it be potentially better if that was Object's implementation?
>>
>> Which was clarified to:
>>
>> #Better in the sense that you would never HAVE to override hashCode.
>>
>> For which the answer is also YES. Per the previous.
>
> No, that's not true. Value-equality maps, for example, would not work if
> you didn't override 'hashCode()' in the key type to match value equality
> on the keys.

That was almost exactly what I answered in my first answer to the original 
poster.

Then I read it as "would it be better if my class used Object's 
implementation".

But after reading the clarification then I think it should be read as "would it 
be better if Object used the implementation shown".

Very different question!

Arne

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Thread

Re: hashCode "Lew" <lew@1:261/38.remove-nlb-this> - 2012-08-13 18:36 +0000
  Re: hashCode "Arne Vajhøj" <������
høj@1:261/38.remove-odu-this> - 2012-08-13 19:38 +0000
  Re: hashCode "Arne Vajhøj" <������
høj@1:261/38.remove-odu-this> - 2012-08-13 19:38 +0000

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