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Groups > comp.lang.java.programmer > #10483

Re: case insensitive sort

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Arne Vajhøj <arne@vajhoej.dk> wrote:
> On 11/26/2011 9:23 AM, Andreas Leitgeb wrote:
>> Arne Vajhøj<arne@vajhoej.dk>  wrote:
>>> On 11/23/2011 12:06 AM, Roedy Green wrote:
>>>> When someone asks for a case insensitive sort, they typically use code
>>>> like this in the Comparator
>>>> return a.x.compareToIgnoreCase( b.x );
>>>> However than will not give you what you really want.  You probably
>>>> want this if you want tidy-looking results.
>>>> int diff = a.x.compareToIgnoreCase( b );
>>>> if ( diff != 0 ) return diff;
>>>> return a.x.compareTo( b.x );
>>> Assuming that whoever asked for a case insensitive sort did not mean
>>> it but wanted a case insensitive sort with those case insensitive equal
>>> sorted case sensitive.
>> Which I consider a pretty safe bet in practise.
>> From a javadoc-link quickly googled:
>> " It is strongly recommended (though not required) that natural orderings be
>> " consistent with equals. [...]
>> This is just another example of where a comparability based only on
>> compareNoCase is likely a bad thing.
> Hm.
> I read it as if you should also override equals.

It surely depends on what the things are, that are being sorted.
You might want to sort items case-insensitively, which may have a 
unique case-sensitive identity. (e.g. filenames on c.s. filesystems)
That's where Roedy's suggestion fits best, imho.

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Thread

case insensitive sort Roedy Green <see_website@mindprod.com.invalid> - 2011-11-22 21:06 -0800
  Re: case insensitive sort Patricia Shanahan <pats@acm.org> - 2011-11-22 21:59 -0800
    Re: case insensitive sort v_borchert@despammed.com (Volker Borchert) - 2011-11-23 06:34 +0000
      Re: case insensitive sort Roedy Green <see_website@mindprod.com.invalid> - 2011-11-23 02:49 -0800
    Re: case insensitive sort Roedy Green <see_website@mindprod.com.invalid> - 2011-11-23 02:46 -0800
      Re: case insensitive sort Patricia Shanahan <pats@acm.org> - 2011-11-23 05:23 -0800
      Re: case insensitive sort v_borchert@despammed.com (Volker Borchert) - 2011-11-23 19:32 +0000
        Re: case insensitive sort dibs <dibs@dobs.dabs> - 2011-11-23 15:11 -0500
          Re: case insensitive sort v_borchert@despammed.com (Volker Borchert) - 2011-11-24 05:03 +0000
  Re: case insensitive sort Arne Vajhøj <arne@vajhoej.dk> - 2011-11-25 21:26 -0500
    Re: case insensitive sort Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-11-26 14:23 +0000
      Re: case insensitive sort Arne Vajhøj <arne@vajhoej.dk> - 2011-12-02 21:56 -0500
        Re: case insensitive sort Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-12-04 10:43 +0000

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