Re: Sorting TimeZone

From:
Lew <lew@lewscanon.com>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 3 Nov 2009 12:44:52 -0800 (PST)
Message-ID:
<921cd01e-120f-4553-a680-d2eece8614f5@b2g2000yqi.googlegroups.com>
Lew wrote :

  Map <TimeZone, String> map =
    new TreeMap <TimeZone, String> ( new Comparator <TimeZone> ()
{ .... } );


Wojtek wrote:

No arguments that this does work.

However I was replying to your statement "'TimeZone' can easily be a map
key, yes, even for a 'TreeMap'. " which appears to say that you do not
need a custom Comparator:


Even though I had explicitly mentioned a custom Comparator in the post
to which you were replying? Come on, now. Your explanation is
disingenuous at best.

Patricia Shanahan wrote:

The natural order and comparator behaviors are equally valid. Throughout
the TreeMap documentation, unqualified statements apply to both cases.
Statements that only apply to the natural order case say so. Given the
way the TreeMap documentation is written, I would not assume a natural
order TreeMap is meant unless the writer says so.


In this case, the writer did explicitly mention use of a custom
Comparator.

I think it is a mistake to treat a Comparable key type as the proper way
to use TreeMap or TreeSet, and a specified Comparator as somehow weird
or "indirect". It can create a mental block to what is often the best
choice for a sorted set or sorted map implementation, when either the
key type does not implement Comparable, or the required order is not its
Comparable order.


What she said, especially since I had actually referred to a custom
Comparator in my post, and others had also chimed in with that same
suggestion, including Wojtek himself! Pretending that that was not
evident smacks of deliberate obtuseness.

--
Lew

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