Groups > comp.lang.java.programmer > #35216

Re: DeDup an ArrayList

Newsgroups	comp.lang.java.programmer
Date	2016-08-05 15:38 -0700
References	<21r7qb1srdvnieuufjquie2qrfujso6l7p@4ax.com> <slrnnq7t3d.456.avl@login.logic.tuwien.ac.at>
Message-ID	<9fe8ddcc-dfd5-4ac1-8438-6f6779bdae9a@googlegroups.com> (permalink)
Subject	Re: DeDup an ArrayList
From	Lew <lewbloch@gmail.com>

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Andreas Leitgeb wrote:
> Roedy Green wrote:
> > This looks like trivial task, but every time I work on it, it keeps
> > ballooning in complexity.
> >
> > I wish to deDup an ArrayList.  Any two strings equalIgnoreCase are
> > considered dups. One should be removed.  The order of the items should
> > be otherwise be undisturbed.
> >
> > Part of the trouble is removing an element from an ArrayList makes you
> > lose track of where you are.
> 
> Copy to a LinkedHashMap (using the toUpperCase()'d string as key, and
> the original String as value), and finally copy back to a new ArrayList...

Two different lower-case strings can upper-case to the same string, and be considered duplicates even though they aren't, in certain languages.

For example, "ß" and "ss" in German (traditionally) both upper-case to "SS".

> The LinkedHashMap will take care of maintaining the ordering, except
> of course, where dups are left out.
> 
> Not sure if hashing on the uppercase version of a String is strictly
> equivalent to pairwise equalIgnoreCase, though. Maybe not, maybe close
> enough, maybe exactly same...  The performance advantage (from n-squared
> to roughly n) might be worth a little slack in some corner cases.

In Greek, '"ς" and "σ", two versions of the Greek sigma, both capitalise to "Σ". '
http://inform7.com/learn/man/WI_20_4.html

-- 
Lew

Thread

DeDup an ArrayList Roedy Green <inquiry@mindprod.com> - 2016-08-04 18:35 -0700
  Re: DeDup an ArrayList Andreas Leitgeb <avl@logic.at> - 2016-08-05 02:05 +0000
    Re: DeDup an ArrayList Arne Vajhøj <arne@vajhoej.dk> - 2016-08-04 22:41 -0400
    Re: DeDup an ArrayList Lew <lewbloch@gmail.com> - 2016-08-05 15:38 -0700
      Re: DeDup an ArrayList Andreas Leitgeb <avl@logic.at> - 2016-08-06 12:10 +0000
  Re: DeDup an ArrayList Roedy Green <inquiry@mindprod.com> - 2016-08-04 19:06 -0700
    Re: DeDup an ArrayList Eric Douglas <e.d.programmer@gmail.com> - 2016-08-05 05:16 -0700
      Re: DeDup an ArrayList Andreas Leitgeb <avl@logic.at> - 2016-08-05 15:30 +0000
        Re: DeDup an ArrayList Eric Douglas <e.d.programmer@gmail.com> - 2016-08-05 10:10 -0700
          Re: DeDup an ArrayList Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-08-05 13:51 -0400
            Re: DeDup an ArrayList Eric Douglas <e.d.programmer@gmail.com> - 2016-08-05 12:16 -0700
              Re: DeDup an ArrayList Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-08-05 15:38 -0400
            Re: DeDup an ArrayList Marcel Mueller <news.5.maazl@spamgourmet.org> - 2016-08-06 00:47 +0200
    Re: DeDup an ArrayList Arne Vajhøj <arne@vajhoej.dk> - 2016-08-05 09:02 -0400
  Re: DeDup an ArrayList Jan Burse <janburse@fastmail.fm> - 2016-08-05 12:52 +0200
    Re: DeDup an ArrayList Jan Burse <janburse@fastmail.fm> - 2016-08-05 12:53 +0200
      Re: DeDup an ArrayList Jan Burse <janburse@fastmail.fm> - 2016-08-05 13:10 +0200
        Re: DeDup an ArrayList Jan Burse <janburse@fastmail.fm> - 2016-08-13 12:26 +0200
  Re: DeDup an ArrayList Daniel Pitts <usenet@coloraura.com> - 2016-08-05 08:37 -0700
    Re: DeDup an ArrayList Knute Johnson <nospam@rabbitbrush.frazmtn.com> - 2016-08-05 08:58 -0700
      Re: DeDup an ArrayList Knute Johnson <nospam@rabbitbrush.frazmtn.com> - 2016-08-05 09:47 -0700
        Re: DeDup an ArrayList Knute Johnson <nospam@rabbitbrush.frazmtn.com> - 2016-08-05 19:56 -0700
        Re: DeDup an ArrayList Daniel Pitts <usenet@coloraura.com> - 2016-08-06 09:18 -0700
  Re: DeDup an ArrayList Marcel Mueller <news.5.maazl@spamgourmet.org> - 2016-08-06 01:04 +0200
  Re: DeDup an ArrayList Roedy Green <inquiry@mindprod.com> - 2016-08-05 16:31 -0700

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