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From "Alex Karasulu" <aok...@bellsouth.net>
Subject RE: [primitives] Looking for a primitive hashtable
Date Thu, 01 Apr 2004 08:03:33 GMT
I'm sure these scenarios were put to the tests several times over with
hashing coming out on top.  

> -----Original Message-----
> From: Tatu Vanhanen [mailto:tatu.vanhanen@graftor.fi]
> Sent: Thursday, April 01, 2004 3:00 AM
> To: Jakarta Commons Users List
> Subject: RE: [primitives] Looking for a primitive hashtable
> 
> 
> > -----Original Message-----
> > From: Alex Karasulu [mailto:aok123@bellsouth.net]
> ...
> > Now the arrays would look like so after these operations are performed:
> >
> >   Keys    Indices   Object Values
> >  ------    -----       -----
> >  |    |    |   |       | +-|-----> "Cat"
> >  ------    -----       -----
> >  |2048|    | 3 |       | +-|-----> "Dog"
> >  ------    -----       -----
> >  | 94 |    | 2 |       |   |       a hole (null)
> >  ------    -----       -----
> >  | 23 |    | 0 |       | +-|-----> "Rat"
> >  ------    -----       -----
> >
> 
> This is exactly what I was thinking of. In addition, I was considering the
> "Keys" to be always sorted, so a binary search (with e.g.
> java.util.Arrays.binarySearch) could be used to lookup the actual index to
> the Object array.
> 
> But more questions raise:
> 1. How much more time it takes to sort after every modification (compared
> to
> standard HashMap modification)?
> 2. How much time does the lookup take (compared to standard HashMap
> lookup)?
> 
> Some hashing needed additionally (don't know anything about that)?
> 
> I was thinking of doing some tests to investigate the actual advantage of
> something like this, but I don't know when I have time.
> 
> And as I mentioned, there are LGPL:ed solutions available (should be
> tested,
> too), but if this kind of stuff is really more efficient and fast than
> using
> standard Map:s then it would be good to find that in e.g.
> commons-primitives.
> 
> I don't need an int-keyed-map now, but probably would some day.
> 
> - Tatu V.
> 
> 
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