Groups > comp.lang.java.programmer > #17850

Re: hashCode

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From	"Lew" <lew@1:261/38.remove-odu-this>
Subject	Re: hashCode
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Date	Mon, 13 Aug 2012 19:38:32 GMT
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  To: =?UTF-8?B?QXJuZSBWYWpow7hq?=
From: "Lew" <lew@1:261/38.remove-nlb-this>

  To: =?UTF-8?B?QXJuZSBWYWpow7hq?=
From: "Lew" <lew@1:261/38.remove-m2z-this>

  To: =?UTF-8?B?QXJuZSBWYWpow7hq?=
From: Lew <noone@lewscanon.com>

Arne Vajh-,j wrote:
> Lew wrote:
>> Jan Burse wrote:
>>> Maybe it would make sense to spell out what the contract
>>> for hashCode() is. Well the contract is simply, the
>>> following invariant should hold:
>>>
>>>     /* invariant that should hold */
>>>     if a.equals(b) then a.hashCode()==b.hashCode()
>>
>> True, but if you read the specification for 'hashCode()' fully, that is
>> not the entire contract, only the compiler-enforceable part of it.
>>
>> The entire specification requires that as much as feasible, the 'Object'
>> implementation distinguish distinct instances, and that the method
>> generally support 'HashMap', which promises O(1) 'get()' and 'put()'
>> with a "proper" (i.e., compliant) 'hashCode()'.
>
> Two wrong statements.
>
> It says that the method is defined to support HashMap
>
> And HashMap does not guarantee O(1) with a correct
> hashCode - it guarantee that for one that return
> good distributed values.

Granted.

--
Lew
Honi soit qui mal y pense.
http://upload.wikimedia.org/wikipedia/commons/c/cf/Friz.jpg

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Re: hashCode "Lew" <lew@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
    Re: hashCode "Lew" <lew@1:261/38.remove-odu-this> - 2012-08-13 19:38 +0000

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