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Re: Help with Deck of cards assignment and getting it to deal...

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From Eric Sosman <esosman@comcast-dot-net.invalid>
Newsgroups comp.lang.java.programmer
Subject Re: Help with Deck of cards assignment and getting it to deal...
Date Sun, 03 Aug 2014 16:49:27 -0400
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On 8/3/2014 3:26 PM, Arne Vajhøj wrote:
>[...]
> I must admit that I can not follow you.
>
> The fact that different games may use a different ordering is
> not an argument against Comparable<>.
>
> Comparable<> is not the one and only ordering. Comparable<> is
> just the natural ordering. It is perfectly valid to have a
> Comparable<> with the natural ordering and a bunch of
> Comparator<> to handle the context specific orderings.

     Although one could select different Comparators for different
games -- one for Ace-low, say, and another for Ace-high -- there
is no way a Comparator could work for "Ace-either" games like Poker
(and certainly not for "Ace-both" games like high-low Poker!).  Like
Comparable, Comparator reflects a _total ordering_ on the objects it
compares, and a total ordering must be transitive:

	If X < Y and Y < Z then X < Z, for all X,Y,Z.

In Poker, one can have

	Ace < Five and Five < Ten but Ten < Ace

... violating transitivity, so the ranks do not follow a total order.

     One could, of course, implement a Comparator (or a Comparable)
that broke the rules and violated its "contractual obligation" to
impose a total order.  But a Comparable/Comparator that didn't behave
as it should would make mockery of the claim

 > Your Card class will be more easily used if it implement the
 > java.lang.Comparable<T> interface

... because none of the Comparable- or Comparator-based utility
classes and methods would behave properly: Collections.sort(),
Arrays.binarySearch(), SortedMap(), ...  Something that simply
doesn't work cannot be "more easily used."

-- 
esosman@comcast-dot-net.invalid

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Thread

Help with Deck of cards assignment and getting it to deal... Scott Dunning <scottwd01@gmail.com> - 2014-08-01 18:16 -0700
  Re: Help with Deck of cards assignment and getting it to deal... Roedy Green <see_website@mindprod.com.invalid> - 2014-08-02 01:42 -0700
    Re: Help with Deck of cards assignment and getting it to deal... Martin Gregorie <martin@address-in-sig.invalid> - 2014-08-02 10:19 +0000
      Re: Help with Deck of cards assignment and getting it to deal... Roedy Green <see_website@mindprod.com.invalid> - 2014-08-03 15:54 -0700
        Re: Help with Deck of cards assignment and getting it to deal... Martin Gregorie <martin@address-in-sig.invalid> - 2014-08-04 13:00 +0000
          Re: Help with Deck of cards assignment and getting it to deal... Arne Vajhøj <arne@vajhoej.dk> - 2014-08-19 17:48 -0400
            Re: Help with Deck of cards assignment and getting it to deal... "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-08-20 10:48 +0100
              Re: Help with Deck of cards assignment and getting it to deal... Arne Vajhøj <arne@vajhoej.dk> - 2014-09-07 21:42 -0400
              Re: Help with Deck of cards assignment and getting it to deal... Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-09-07 22:04 -0400
                Re: Help with Deck of cards assignment and getting it to deal... Arne Vajhøj <arne@vajhoej.dk> - 2014-09-07 22:08 -0400
  Re: Help with Deck of cards assignment and getting it to deal... Mike Amling <mamling@chaff.us> - 2014-08-03 07:38 -0500
  Re: Help with Deck of cards assignment and getting it to deal... Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-03 10:23 -0400
    Re: Help with Deck of cards assignment and getting it to deal... lipska the kat <lipskathekat@example.com> - 2014-08-03 18:52 +0100
      Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 14:16 -0400
        Re: Help with Deck of cards assignment and getting it to deal... lipska the kat <lipskathekat@example.com> - 2014-08-03 19:21 +0100
          Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 14:38 -0400
            Re: Help with Deck of cards assignment and getting it to deal... lipska the kat <lipskathekat@example.com> - 2014-08-03 19:41 +0100
    Re: Help with Deck of cards assignment and getting it to deal... Mike Amling <mamling@chaff.us> - 2014-08-03 16:05 -0500
  Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 11:08 -0400
    Re: Help with Deck of cards assignment and getting it to deal... Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-03 11:41 -0400
      Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 13:25 -0400
        Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 13:36 -0400
          Re: Help with Deck of cards assignment and getting it to deal... David Postill <david.postill@gmail.com> - 2014-08-04 09:00 +0200
        Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 13:47 -0400
          Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 13:52 -0400
            Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 14:10 -0400
        Re: Help with Deck of cards assignment and getting it to deal... Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-03 15:00 -0400
          Re: Help with Deck of cards assignment and getting it to deal... Arne Vajhøj <arne@vajhoej.dk> - 2014-08-03 15:26 -0400
            Re: Help with Deck of cards assignment and getting it to deal... lipska the kat <lipskathekat@example.com> - 2014-08-03 20:34 +0100
            Re: Help with Deck of cards assignment and getting it to deal... Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-03 16:49 -0400
              Re: Help with Deck of cards assignment and getting it to deal... Arne Vajhøj <arne@vajhoej.dk> - 2014-08-03 17:01 -0400
                Re: Help with Deck of cards assignment and getting it to deal... "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-08-04 20:32 +0100
                Re: Help with Deck of cards assignment and getting it to deal... Arne Vajhøj <arne@vajhoej.dk> - 2014-08-19 17:45 -0400
                Re: Help with Deck of cards assignment and getting it to deal... "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-08-20 10:50 +0100
                Re: Help with Deck of cards assignment and getting it to deal... Brixomatic <brixomatic@yahoo.com> - 2014-08-31 10:17 +0200
                Re: Help with Deck of cards assignment and getting it to deal... "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-09-04 15:14 +0100
                Re: Help with Deck of cards assignment and getting it to deal... Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-09-04 10:55 -0400
                Re: Help with Deck of cards assignment and getting it to deal... "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-09-04 16:12 +0100
                [OT] Re: Help with Deck of cards assignment and getting it to deal... Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-09-04 15:05 -0400
                Re: Help with Deck of cards assignment and getting it to deal... Gene Wirchenko <genew@telus.net> - 2014-09-05 10:03 -0700
                Re: Help with Deck of cards assignment and getting it to deal... Arne Vajhøj <arne@vajhoej.dk> - 2014-09-07 21:45 -0400
                Re: Help with Deck of cards assignment and getting it to deal... Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-09-07 22:13 -0400
              Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 17:19 -0400
                Re: Help with Deck of cards assignment and getting it to deal... Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-04 08:14 -0400
                Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-04 20:03 -0400
                Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-04 20:29 -0400
          Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 15:45 -0400
            Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 16:01 -0400
              Re: Help with Deck of cards assignment and getting it to deal... Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-03 17:05 -0400
                Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 17:37 -0400
                Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 18:19 -0400
                Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 18:34 -0400
                Re: Help with Deck of cards assignment and getting it to deal... Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-03 20:37 -0400
                Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 20:40 -0400
                Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 20:49 -0400
                Re: Help with Deck of cards assignment and getting it to deal... Jeff Higgins <jeff@invalid.invalid> - 2014-08-03 18:09 -0400
  Re: Help with Deck of cards assignment and getting it to deal... Roedy Green <see_website@mindprod.com.invalid> - 2014-08-04 18:43 -0700
    Re: Help with Deck of cards assignment and getting it to deal... "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-08-05 11:19 +0100
      Re: Help with Deck of cards assignment and getting it to deal... "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-08-05 11:28 +0100
  Re: Help with Deck of cards assignment and getting it to deal... lipska the kat <lipskathekat@example.com> - 2014-08-31 17:31 +0100

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