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Groups > comp.lang.java.programmer > #18336
| From | Daniel Pitts <newsgroup.nospam@virtualinfinity.net> |
|---|---|
| Newsgroups | comp.lang.java.programmer |
| Subject | Re: hashCode |
| References | (5 earlier) <5028191b$0$290$14726298@news.sunsite.dk> <a8sr5sFropU1@mid.individual.net> <50317b03$0$281$14726298@news.sunsite.dk> <slrnk36phl.u9l.avl@gamma.logic.tuwien.ac.at> <503bfd0f$0$282$14726298@news.sunsite.dk> |
| Message-ID | <CNT_r.5387$pd4.3890@newsfe21.iad> (permalink) |
| Date | 2012-08-27 16:55 -0700 |
On 8/27/12 4:04 PM, Arne Vajhøj wrote: > On 8/21/2012 6:43 AM, Andreas Leitgeb wrote: >> Arne Vajhøj <arne@vajhoej.dk> wrote: >>> We are looking at two alternatives: >>> A) default functions properly but good performance requires an override >>> B) default gives good performance but may need an override to function >>> properly >> >> C) default hashCode() works perfectly well with default equals(), and >> only >> those with a specific requirement for equality, who thus need to >> override >> .equals(), anyway, also need to override hashCode() appropriately for >> their specific equality-relation. > > That is just B in another wording. However you word it. The truth is that equals/hashCode should probably be overridden together, or together remain default. I find it somewhat disappointing that there are Comparable/Comparator interfaces, but no Hashable/Hasher interfaces. As it turns out, usually equals doesn't work well with subclasses anyway, so to have an external "equals" predicate makes for a cleaner abstraction.
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hashCode bob smith <bob@coolfone.comze.com> - 2012-08-10 08:47 -0700
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-10 12:13 -0400
Re: hashCode markspace <-@.> - 2012-08-10 10:13 -0700
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-10 13:38 -0400
Re: hashCode rossum <rossum48@coldmail.com> - 2012-08-11 10:36 +0100
Re: hashCode Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-10 12:34 -0400
Re: hashCode bob smith <bob@coolfone.comze.com> - 2012-08-10 15:22 -0700
Re: hashCode Lew <lewbloch@gmail.com> - 2012-08-10 15:32 -0700
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-10 19:30 -0400
Re: hashCode Lew <noone@lewscanon.com> - 2012-08-11 16:24 -0700
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-11 22:15 -0400
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-11 22:29 -0400
Re: hashCode Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-11 22:43 -0400
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-11 22:54 -0400
Re: hashCode Lew <noone@lewscanon.com> - 2012-08-11 21:46 -0700
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-12 16:53 -0400
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-12 17:00 -0400
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-10 19:27 -0400
Re: hashCode Robert Klemme <shortcutter@googlemail.com> - 2012-08-12 17:06 +0200
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-12 16:59 -0400
Re: hashCode Robert Klemme <shortcutter@googlemail.com> - 2012-08-13 19:17 +0200
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-19 19:42 -0400
Re: hashCode Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2012-08-21 10:30 +0000
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-19 19:47 -0400
Re: hashCode Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2012-08-21 10:43 +0000
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-27 19:04 -0400
Re: hashCode Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-08-27 16:55 -0700
Re: hashCode markspace <-@.> - 2012-08-27 17:03 -0700
Re: hashCode Lew <lewbloch@gmail.com> - 2012-08-27 17:49 -0700
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-27 21:37 -0400
Re: hashCode Patricia Shanahan <pats@acm.org> - 2012-08-27 18:58 -0700
Re: hashCode markspace <-@.> - 2012-08-27 21:19 -0700
Re: hashCode Patricia Shanahan <pats@acm.org> - 2012-08-28 01:06 -0700
Re: hashCode markspace <-@.> - 2012-08-28 09:19 -0700
Re: hashCode Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-08-28 16:33 -0700
Re: hashCode markspace <-@.> - 2012-08-28 17:02 -0700
Re: hashCode Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-08-29 11:06 -0700
Re: hashCode Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-29 14:49 -0400
Re: hashCode Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-08-29 13:40 -0700
Re: hashCode Gene Wirchenko <genew@ocis.net> - 2012-08-29 18:02 -0700
Re: hashCode Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2012-08-31 00:52 +0200
Re: hashCode Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-30 21:43 -0400
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-30 21:52 -0400
Re: hashCode Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2012-08-31 04:18 +0200
Re: hashCode Jim Janney <jjanney@shell.xmission.com> - 2012-08-31 09:08 -0600
Re: hashCode Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-31 11:38 -0400
Re: hashCode Robert Klemme <shortcutter@googlemail.com> - 2012-08-31 17:55 +0200
Re: hashCode Jim Janney <jjanney@shell.xmission.com> - 2012-08-31 09:56 -0600
Re: hashCode Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-31 14:32 -0400
Re: hashCode Jim Janney <jjanney@shell.xmission.com> - 2012-08-31 14:38 -0600
Re: hashCode Lew <lewbloch@gmail.com> - 2012-08-31 15:33 -0700
Re: hashCode Jim Janney <jjanney@shell.xmission.com> - 2012-08-31 16:41 -0600
Re: hashCode Lew <lewbloch@gmail.com> - 2012-08-31 16:26 -0700
Re: hashCode Jim Janney <jjanney@shell.xmission.com> - 2012-09-02 11:54 -0600
Re: hashCode Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2012-09-03 00:47 +0200
Re: hashCode Jim Janney <jjanney@shell.xmission.com> - 2012-09-03 21:44 -0600
Re: hashCode Jim Janney <jjanney@shell.xmission.com> - 2012-08-31 09:08 -0600
Re: hashCode Robert Klemme <shortcutter@googlemail.com> - 2012-08-31 17:58 +0200
Re: hashCode markspace <-@.> - 2012-08-29 11:51 -0700
Re: hashCode Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-08-29 13:28 -0700
Re: hashCode markspace <-@.> - 2012-08-29 16:05 -0700
Re: hashCode Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-08-29 16:23 -0700
Re: hashCode Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-29 20:56 -0400
Re: hashCode Jan Burse <janburse@fastmail.fm> - 2012-08-30 11:19 +0200
Re: hashCode Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-08-30 10:03 -0700
Re: hashCode Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2012-08-30 18:34 +0000
Re: hashCode Jim Janney <jjanney@shell.xmission.com> - 2012-08-30 08:11 -0600
Re: hashCode Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-08-30 10:06 -0700
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-30 19:16 -0400
Re: hashCode Lew <lewbloch@gmail.com> - 2012-08-28 13:58 -0700
Re: hashCode Lew <lewbloch@gmail.com> - 2012-08-28 13:56 -0700
Re: hashCode Patricia Shanahan <pats@acm.org> - 2012-08-28 14:07 -0700
Re: hashCode Lew <lewbloch@gmail.com> - 2012-08-28 14:38 -0700
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-27 21:12 -0400
Re: hashCode Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-11 07:58 -0400
Re: hashCode Lew <noone@lewscanon.com> - 2012-08-11 16:29 -0700
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-11 22:16 -0400
Re: hashCode Patricia Shanahan <pats@acm.org> - 2012-08-12 03:46 -0700
Re: hashCode Joshua Cranmer <Pidgeot18@verizon.invalid> - 2012-08-12 12:23 -0400
Re: hashCode Patricia Shanahan <pats@acm.org> - 2012-08-12 09:40 -0700
Re: hashCode Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-12 13:59 -0400
Re: hashCode Patricia Shanahan <pats@acm.org> - 2012-08-12 11:17 -0700
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-12 17:02 -0400
Re: hashCode Jan Burse <janburse@fastmail.fm> - 2012-08-12 19:03 +0200
Re: hashCode Roedy Green <see_website@mindprod.com.invalid> - 2012-08-10 12:17 -0700
Re: hashCode Lew <lewbloch@gmail.com> - 2012-08-10 12:45 -0700
Re: hashCode Roedy Green <see_website@mindprod.com.invalid> - 2012-08-11 04:54 -0700
Re: hashCode Joerg Meier <joergmmeier@arcor.de> - 2012-08-11 18:25 +0200
Re: hashCode Mike Winter <usenet@michael-winter.me.invalid> - 2012-08-11 18:53 +0100
Re: hashCode Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2012-08-11 09:56 -0700
Re: hashCode Jan Burse <janburse@fastmail.fm> - 2012-08-11 18:58 +0200
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-11 22:40 -0400
Re: hashCode rossum <rossum48@coldmail.com> - 2012-08-11 18:47 +0100
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-10 19:25 -0400
Re: hashCode Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-11 08:00 -0400
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-11 09:49 -0400
Re: hashCode Jan Burse <janburse@fastmail.fm> - 2012-08-11 15:33 +0200
Re: hashCode Jan Burse <janburse@fastmail.fm> - 2012-08-11 15:34 +0200
Re: hashCode Lew <noone@lewscanon.com> - 2012-08-11 16:34 -0700
Re: hashCode Lew <noone@lewscanon.com> - 2012-08-11 16:37 -0700
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-11 22:19 -0400
Re: hashCode Lew <noone@lewscanon.com> - 2012-08-11 21:48 -0700
Re: hashCode Jan Burse <janburse@fastmail.fm> - 2012-08-12 12:08 +0200
Re: hashCode Jan Burse <janburse@fastmail.fm> - 2012-08-12 12:18 +0200
Re: hashCode Lew <noone@lewscanon.com> - 2012-08-12 11:27 -0700
Re: hashCode Arne Vajhøj <arne@vajhoej.dk> - 2012-08-12 17:11 -0400
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