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Re: hashCode

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From "rossum" <rossum@1:261/38.remove-ya-this>
Subject Re: hashCode
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  To: Lew
From: rossum <rossum48@coldmail.com>

On Fri, 10 Aug 2012 12:45:07 -0700 (PDT), Lew <lewbloch@gmail.com> wrote:

>public static int calculateHash(Foo arg) {
>   int h = 0;
>
>   for ( each attribute of Foo that contributes to 'equals()' )
>   {
>        h = 31 * h + attribute.hashCode();
>   }
>   return h;
>}
Bloch starts with:

  int h = 17;

He says that works beter in cases where the first one or more 
attribute.hashCode() values are zero, and hence will not register.

He suggessts any constant non-zero value.

rossum

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hashCode "bob smith" <bob.smith@1:261/38.remove-t9h-this> - 2012-08-10 18:39 +0000
  Re: hashCode "Arne Vajhøj" <arne.vajhøj@1:261/38.remove-t9h-this> - 2012-08-10 18:39 +0000
    Re: hashCode "markspace" <markspace@1:261/38.remove-t9h-this> - 2012-08-10 18:39 +0000
      Re: hashCode "Arne Vajhøj" <arne.vajhøj@1:261/38.remove-t9h-this> - 2012-08-10 18:39 +0000
        Re: hashCode "rossum" <rossum@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
  Re: hashCode "Eric Sosman" <eric.sosman@1:261/38.remove-t9h-this> - 2012-08-10 18:39 +0000
    Re: hashCode "bob smith" <bob.smith@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
      Re: hashCode "Lew" <lew@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
        Re: hashCode "Arne Vajhøj" <arne.vajhøj@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
          Re: hashCode "Lew" <lew@1:261/38.remove-m2z-this> - 2012-08-12 18:58 +0000
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              Re: hashCode "Arne Vajhøj" <������
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                Re: hashCode "Eric Sosman" <eric.sosman@1:261/38.remove-m2z-this> - 2012-08-12 18:58 +0000
                Re: hashCode "Arne Vajhøj" <������
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          Re: hashCode "Arne Vajhøj" <������
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      Re: hashCode "Arne Vajhøj" <arne.vajhøj@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
        Re: hashCode "Robert Klemme" <robert.klemme@1:261/38.remove-m2z-this> - 2012-08-12 18:58 +0000
          Re: hashCode "Arne Vajhøj" <arne.vajhøj@1:261/38.remove-nlb-this> - 2012-08-13 18:36 +0000
            Re: hashCode "Robert Klemme" <robert.klemme@1:261/38.remove-nlb-this> - 2012-08-13 18:36 +0000
              Re: hashCode "Arne Vajhøj" <arne.vajhøj@1:261/38.remove-fzq-this> - 2012-08-20 18:58 +0000
              Re: hashCode "Arne Vajhøj" <arne.vajhøj@1:261/38.remove-fzq-this> - 2012-08-20 18:58 +0000
      Re: hashCode "Patricia Shanahan" <patricia.shanahan@1:261/38.remove-m2z-this> - 2012-08-12 18:58 +0000
      Re: hashCode "Joshua Cranmer" <joshua.cranmer@1:261/38.remove-m2z-this> - 2012-08-12 18:58 +0000
        Re: hashCode "Patricia Shanahan" <patricia.shanahan@1:261/38.remove-m2z-this> - 2012-08-12 18:58 +0000
          Re: hashCode "Eric Sosman" <eric.sosman@1:261/38.remove-6fd-this> - 2012-08-12 20:00 +0000
            Re: hashCode "Patricia Shanahan" <patricia.shanahan@1:261/38.remove-6fd-this> - 2012-08-12 20:00 +0000
          Re: hashCode "Arne Vajhøj" <������
høj@1:261/38.remove-nlb-this> - 2012-08-13 18:36 +0000
        Re: hashCode "Jan Burse" <jan.burse@1:261/38.remove-m2z-this> - 2012-08-12 18:58 +0000
  Re: hashCode "Roedy Green" <roedy.green@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
    Re: hashCode "Lew" <lew@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
      Re: hashCode "Roedy Green" <roedy.green@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
        Re: hashCode "Joerg Meier" <joerg.meier@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
          Re: hashCode "Mike Winter" <mike.winter@1:261/38.remove-ya-this> - 2012-08-11 19:19 +0000
        Re: hashCode "Peter Duniho" <peter.duniho@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
        Re: hashCode "Jan Burse" <jan.burse@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
        Re: hashCode "Arne Vajhøj" <arne.vajhøj@1:261/38.remove-m2z-this> - 2012-08-12 18:58 +0000
      Re: hashCode "rossum" <rossum@1:261/38.remove-ya-this> - 2012-08-11 19:19 +0000
    Re: hashCode "Arne Vajhøj" <arne.vajhøj@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
      Re: hashCode "Eric Sosman" <eric.sosman@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
        Re: hashCode "Arne Vajhøj" <arne.vajhøj@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
  Re: hashCode "Jan Burse" <jan.burse@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
    Re: hashCode "Jan Burse" <jan.burse@1:261/38.remove-pjg-this> - 2012-08-11 18:17 +0000
    Re: hashCode "Lew" <lew@1:261/38.remove-m2z-this> - 2012-08-12 18:58 +0000
      Re: hashCode "Lew" <lew@1:261/38.remove-m2z-this> - 2012-08-12 18:58 +0000
      Re: hashCode "Arne Vajhøj" <������
høj@1:261/38.remove-m2z-this> - 2012-08-12 18:58 +0000
        Re: hashCode "Lew" <lew@1:261/38.remove-m2z-this> - 2012-08-12 18:58 +0000
    Re: hashCode "Jan Burse" <jan.burse@1:261/38.remove-m2z-this> - 2012-08-12 18:58 +0000
      Re: hashCode "Jan Burse" <jan.burse@1:261/38.remove-m2z-this> - 2012-08-12 18:58 +0000
      Re: hashCode "Lew" <lew@1:261/38.remove-6fd-this> - 2012-08-12 20:00 +0000
        Re: hashCode "Arne Vajhøj" <������
høj@1:261/38.remove-nlb-this> - 2012-08-13 18:36 +0000

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