Re: Can I compare references (in a sense of compareTo method)?

From:
 Daniel Pitts <googlegroupie@coloraura.com>
Newsgroups:
comp.lang.java.programmer
Date:
Fri, 21 Sep 2007 15:18:40 -0000
Message-ID:
<1190387920.333860.198720@q3g2000prf.googlegroups.com>
On Sep 21, 12:26 am, chucky <tomas.mik...@gmail.com> wrote:

Thank you guys, seems you have answered my question indirectly --
there is no way to get the address of an object :-).

On Sep 20, 11:42 pm, Daniel Pitts <googlegrou...@coloraura.com> wrote:

Now, the questions remains, if they don't have inherent order, why use
them in a TreeSet or TreeMap? Why not a standard HashSet/HashMap?
The main benefit of Tree* is that it maintains the order for you.


I don't care about the actual ordering, but I wanted to use Tree*
since I thought it would have smaller memory overhead than Hash*. I
don't care much about logarithmic complexity (which is btw.
guaranteed, while Hash operations don't guarantee constant
complexity), since I want to use it for small collections (<20
elements).

Why is HashSet/HashMap more standard than TreeSet/TreeMap?

T.


Hash doesn't have a huge memory overhead, and generally you shouldn't
worry about such things until they become a problem.

If you declare your sets/maps using the interface "Set<MyThing>" and
"Map<MyThing, OtherThing>", then you can switch between different
implementations.

HashSet and HashMap are the default choice, because they are on
average O(1) operations. TreeSet and TreeMap have a very specific
purpose, and that purpose is to guarantee and ordering of elements.

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