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Groups > comp.lang.java.programmer > #21407

Re: idea for more efficient HashMap

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In article <9hc2f8ltgn1bmdsrk8vb9kuu1vi5dkl2r5@4ax.com>,
 Roedy Green <see_website@mindprod.com.invalid> wrote:

> Inside HashMap are little glue Entry objects that point to the key and
> value.
> 
> What if you could implement an interface on your objects so that
> HashMap could use them directly without separate key or Entry glue?.
> 
> e.g. getKey()
>        getPrev()
>        getNext()
>        setPrev()
>        setNext()
> 
> One drawback would be your objects could live on only one such
> space-efficient HashMap.

I've done this when efficiency demanded it.  The downside is that you 
can't implement java.util.Map or java.util.Dictionary because of the way 
put(K,V) is declared.

There's no need for hashed storage in Maps.  Hashing is a good general 
purpose performer but special cases can do better.  Maps having 1 to 10 
elements may perform better with the keys and values interleaved in one 
array.  A search tree (TreeMap) can perform better when keys are large.
-- 
I will not see posts from Google because I must filter them as spam

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idea for more efficient HashMap Roedy Green <see_website@mindprod.com.invalid> - 2013-01-12 01:55 -0800
  Re: idea for more efficient HashMap v_borchert@despammed.com (Volker Borchert) - 2013-01-12 14:21 +0000
  Re: idea for more efficient HashMap Robert Klemme <shortcutter@googlemail.com> - 2013-01-13 19:44 +0100
  Re: idea for more efficient HashMap Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2013-01-14 21:56 -0800
    Re: idea for more efficient HashMap Robert Klemme <shortcutter@googlemail.com> - 2013-01-16 14:31 -0800
      Re: idea for more efficient HashMap Lars Enderin <lars.enderin@telia.com> - 2013-01-17 10:23 +0100
        Re: idea for more efficient HashMap Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2013-01-17 19:30 -0800
          Re: idea for more efficient HashMap Robert Klemme <shortcutter@googlemail.com> - 2013-01-20 20:28 +0100
          Re: idea for more efficient HashMap Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-01-20 14:49 -0500
          Re: idea for more efficient HashMap Roedy Green <see_website@mindprod.com.invalid> - 2013-01-29 01:41 -0800
            Re: idea for more efficient HashMap Arne Vajhøj <arne@vajhoej.dk> - 2013-01-29 22:03 -0500
              Re: idea for more efficient HashMap Gene Wirchenko <genew@telus.net> - 2013-01-30 11:34 -0800
                Re: idea for more efficient HashMap Arne Vajhøj <arne@vajhoej.dk> - 2013-01-30 21:35 -0500
                Re: idea for more efficient HashMap Gene Wirchenko <genew@telus.net> - 2013-01-31 10:47 -0800
                Re: idea for more efficient HashMap Arne Vajhøj <arne@vajhoej.dk> - 2013-02-01 19:57 -0500

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