Groups > comp.lang.java.programmer > #17795

Re: hashCode

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From	"Lew" <lew@1:261/38.remove-nlb-this>
Subject	Re: hashCode
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  To: Jan Burse
From: "Lew" <lew@1:261/38.remove-m2z-this>

  To: Jan Burse
From: Lew <noone@lewscanon.com>

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()'.

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

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