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Re: ArrayList vs HashMap

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Roedy Green schrieb:
> Hash anyone ever experimented to find a rule of thumb about what sizes
> lookup should be done with ArrayList and which with HashMap?

The Java compiler implements some rule of thumbs
in its switch statement compilation. It has two
options to emit a scan or an index lookup byte
code instruction.

Similarly you can use an array list to scan
and implement a map. Just store key value pairs
or distribute the keys and values along array
elements, resulting in an array of double size.

Here is the Java heuristic:
http://stackoverflow.com/a/31032054/502187

This doesn't directly answer your question, but
I have a similar case between ArrayList
and HashSet, and simply used threshold on the number
of key value pairs which I determined empirically.
There is not only a time tradeoff but also a
space tradeoff.

Since using less space was also important for
me I was choosing a higher threshold of 12
key value pairs or so. Otherwise I would use 8
key value pairs or so.

Bye

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ArrayList vs HashMap Roedy Green <inquiry@mindprod.com> - 2016-08-25 09:42 -0700
  Re: ArrayList vs HashMap Roedy Green <inquiry@mindprod.com> - 2016-08-25 09:43 -0700
    Re: ArrayList vs HashMap Eric Douglas <e.d.programmer@gmail.com> - 2016-08-25 10:06 -0700
      Re: ArrayList vs HashMap Roedy Green <inquiry@mindprod.com> - 2016-08-30 16:34 -0700
        Re: ArrayList vs HashMap Andreas Leitgeb <avl@logic.at> - 2016-08-31 12:55 +0000
          Re: ArrayList vs HashMap Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-08-31 13:05 -0400
            Re: ArrayList vs HashMap Andreas Leitgeb <avl@logic.at> - 2016-08-31 17:34 +0000
  Re: ArrayList vs HashMap j4n bur53 <janburse@fastmail.fm> - 2016-08-31 09:15 +0200

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