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

From:

Lew <lew@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Fri, 21 Sep 2007 08:45:46 -0400

Message-ID:

<fJGdnSHAT6BnIW7bnZ2dnUVZ_vyinZ2d@comcast.com>

chucky writes:

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

Lasse Reichstein Nielsen wrote:

It doesn't require its keys to be Comparable, or have a Comparator.

chucky writes:

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).

"Premature optimization is the root of all evil." - Knuth

You are mistaken about "Hash [sic] operations don't guarantee constant
complexity".

<http://java.sun.com/javase/6/docs/api/java/util/HashMap.html>

This implementation provides constant-time performance for
the basic operations (get and put), assuming the hash function
disperses the elements properly among the buckets.

Whereas
<http://java.sun.com/javase/6/docs/api/java/util/TreeMap.html>

This implementation provides guaranteed log(n) time cost
for the containsKey, get, put and remove operations.

--
Lew