Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.java.programmer > #20465
| Newsgroups | comp.lang.java.programmer |
|---|---|
| Date | 2012-12-18 10:56 -0800 |
| References | <e6f674ec-f00d-4b22-bc02-e1c0ff9ff196@oi3g2000pbb.googlegroups.com> <d8WdnQ4s7tp82k3NnZ2dnUVZ8smdnZ2d@bt.com> |
| Message-ID | <f813a1f1-a714-414d-a62b-8c23ed944b7d@googlegroups.com> (permalink) |
| Subject | Re: Need clarification on Object.equals. |
| From | plewto@gmail.com |
On Tuesday, December 18, 2012 4:39:27 AM UTC-6, lipska the kat wrote:
> On 18/12/12 08:13,
>
> > In the following code Node is an abstract class and both Gate and
>
> > Monitor are extensions of Node. a and b are distinct objects yet
>
> > a.equals(b) is returning true.
>
> >
>
> > public class Foo {
>
> > public static void main(String[] argv){
>
> > Node a = new Gate();
>
> > Monitor b = new Monitor();
>
> > System.out.println(a.equals(b)); // --> prints 'true'
>
> > }
>
> > }
>
>
>
> According to the documentation the contract for equals on instances of
>
> class Object is as follows
>
>
>
> "The equals method for class Object implements the most discriminating
>
> possible equivalence relation on objects; that is, for any non-null
>
> reference values x and y, this method returns true if and only if x and
>
> y refer to the same object (x == y has the value true)."
>
>
>
> This is obviously the not the case in your example above.
>
> Does the class Node or any of it's superclasses override the equals method ?
>
>
>
> The following code returns false as expected
>
>
>
> public abstract class Foo {
>
>
>
> public static void main(String args[]){
>
> Foo bar = new Bar();
>
> Baz baz = new Baz();
>
> System.out.println(bar.equals(baz));
>
> }
>
> }
>
>
>
> class Bar extends Foo{}
>
>
>
> class Baz extends Foo{}
>
>
>
> ...
>
>
>
> However, add the following method to the class Foo
>
>
>
> public boolean equals(Object obj){
>
> return true;
>
> }
>
>
>
> and re-run the code and we get true.
>
>
>
> Has someone been messing with equals ?
>
>
>
> lipska
>
>
>
> --
>
> Lipska the Kat�: Troll hunter, sandbox destroyer
>
> and farscape dreamer of Aeryn Sun
Thanks for your response,
I see where the problem is. I do not directly implement equals, however Node is an extension of AbstractSet which does redefine equals. As it turns out I was in the process of rewriting Node so that it no longer extends AbsteractSet when the anomaly popped up in test code, so it is actually a mote point.
Back to comp.lang.java.programmer | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Need clarification on Object.equals. "plewto@gmail.com" <plewto@gmail.com> - 2012-12-18 00:13 -0800
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-18 10:39 +0000
Re: Need clarification on Object.equals. Roedy Green <see_website@mindprod.com.invalid> - 2012-12-18 04:48 -0800
Re: Need clarification on Object.equals. Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2012-12-18 10:56 -0800
Re: Need clarification on Object.equals. FredK <fred.l.kleinschmidt@gmail.com> - 2012-12-19 08:13 -0800
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 11:22 -0500
Re: Need clarification on Object.equals. Lars Enderin <lars.enderin@telia.com> - 2012-12-19 17:43 +0100
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 12:06 -0500
Re: Need clarification on Object.equals. Patricia Shanahan <pats@acm.org> - 2012-12-19 09:39 -0800
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 13:24 -0500
Re: Need clarification on Object.equals. FredK <fred.l.kleinschmidt@gmail.com> - 2012-12-19 11:23 -0800
Re: Need clarification on Object.equals. Patricia Shanahan <pats@acm.org> - 2012-12-19 08:25 -0800
Re: Need clarification on Object.equals. plewto@gmail.com - 2012-12-18 10:56 -0800
Re: Need clarification on Object.equals. Jim Janney <jjanney@shell.xmission.com> - 2012-12-18 14:24 -0700
Re: Need clarification on Object.equals. Patricia Shanahan <pats@acm.org> - 2012-12-18 13:52 -0800
Re: Need clarification on Object.equals. markspace <-@.> - 2012-12-18 10:24 -0800
Re: Need clarification on Object.equals. plewto@gmail.com - 2012-12-18 10:48 -0800
Re: Need clarification on Object.equals. David Lamb <dalamb@cs.queensu.ca> - 2012-12-18 14:01 -0500
Re: Need clarification on Object.equals. plewto@gmail.com - 2012-12-18 12:14 -0800
Re: Need clarification on Object.equals. plewto@gmail.com - 2012-12-18 12:17 -0800
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-18 22:16 -0500
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 10:20 +0000
Re: Need clarification on Object.equals. Patricia Shanahan <pats@acm.org> - 2012-12-19 03:22 -0800
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 12:06 +0000
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 09:07 -0500
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 09:09 -0500
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 14:36 +0000
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 09:42 -0500
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 15:05 +0000
Re: Need clarification on Object.equals. Lars Enderin <lars.enderin@telia.com> - 2012-12-19 16:15 +0100
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 15:47 +0000
Re: Need clarification on Object.equals. Lars Enderin <lars.enderin@telia.com> - 2012-12-19 16:57 +0100
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 16:51 +0000
Re: Need clarification on Object.equals. Lars Enderin <lars.enderin@telia.com> - 2012-12-19 18:12 +0100
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 17:27 +0000
Re: Need clarification on Object.equals. Gene Wirchenko <genew@telus.net> - 2012-12-19 11:40 -0800
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 10:17 -0500
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 15:40 +0000
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 10:50 -0500
Re: Need clarification on Object.equals. Lars Enderin <lars.enderin@telia.com> - 2012-12-19 17:01 +0100
Re: Need clarification on Object.equals. Gene Wirchenko <genew@telus.net> - 2012-12-19 10:22 -0800
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 18:49 +0000
Re: Need clarification on Object.equals. Gene Wirchenko <genew@telus.net> - 2012-12-19 11:41 -0800
Re: Need clarification on Object.equals. Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2012-12-19 17:05 -0800
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-20 08:34 +0000
Re: Need clarification on Object.equals. Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2012-12-20 07:27 -0800
Re: Need clarification on Object.equals. Gene Wirchenko <genew@telus.net> - 2012-12-20 09:04 -0800
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-20 18:10 +0000
Re: Need clarification on Object.equals. Lew <lewbloch@gmail.com> - 2012-12-20 11:08 -0800
Re: Need clarification on Object.equals. Peter Dunihơ <Np0eStPeAdM@NnOwSlPiAnMk.com> - 2012-12-21 07:50 +0000
Re: Need clarification on Object.equals. Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2012-12-21 07:30 -0800
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-21 17:09 +0000
Re: Need clarification on Object.equals. Leŵ <lewbl0ch@gmail.com> - 2012-12-23 00:54 +0000
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-21 12:23 -0500
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-21 17:38 +0000
Re: Need clarification on Object.equals. Arne Vajhoj <arne@vajhoj.dk> - 2012-12-23 00:50 +0000
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-21 08:39 +0000
Re: Need clarification on Object.equals. Gene Wirchenko <genew@telus.net> - 2012-12-20 13:39 -0800
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-21 08:34 +0000
Re: Need clarification on Object.equals. Leif Roar Moldskred <leifm@dimnakorr.com> - 2012-12-19 09:22 -0600
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 15:35 +0000
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 10:56 -0500
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 17:08 +0000
Re: Need clarification on Object.equals. Joshua Cranmer <Pidgeot18@verizon.invalid> - 2012-12-19 08:58 -0600
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 15:32 +0000
Re: Need clarification on Object.equals. Joshua Cranmer <Pidgeot18@verizon.invalid> - 2012-12-19 11:08 -0600
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 17:32 +0000
Re: Need clarification on Object.equals. Lars Enderin <lars.enderin@telia.com> - 2012-12-19 18:41 +0100
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 17:58 +0000
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 18:12 +0000
Re: Need clarification on Object.equals. Joshua Cranmer <Pidgeot18@verizon.invalid> - 2012-12-19 12:29 -0600
Re: Need clarification on Object.equals. Joshua Cranmer <Pidgeot18@verizon.invalid> - 2012-12-19 12:00 -0600
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 18:06 +0000
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 13:13 -0500
Re: Need clarification on Object.equals. Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2012-12-19 07:48 -0800
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 16:48 +0000
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 12:09 -0500
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 17:50 +0000
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 13:14 -0500
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 18:59 +0000
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 13:16 -0500
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 19:05 +0000
Re: Need clarification on Object.equals. Gene Wirchenko <genew@telus.net> - 2012-12-19 11:45 -0800
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 20:00 +0000
Re: Need clarification on Object.equals. Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2012-12-19 17:15 -0800
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-20 09:22 +0000
Re: Need clarification on Object.equals. Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2012-12-20 07:36 -0800
Re: Need clarification on Object.equals. Gene Wirchenko <genew@telus.net> - 2012-12-19 10:19 -0800
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-19 19:16 +0000
Re: Need clarification on Object.equals. Gene Wirchenko <genew@telus.net> - 2012-12-19 11:48 -0800
Re: Need clarification on Object.equals. Leif Roar Moldskred <leifm@dimnakorr.com> - 2012-12-19 14:12 -0600
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 09:04 -0500
Re: Need clarification on Object.equals. Lew <lewbloch@gmail.com> - 2012-12-19 13:40 -0800
Re: Need clarification on Object.equals. lipska the kat <lipskathekat@yahoo.co.uk> - 2012-12-20 09:30 +0000
Re: Need clarification on Object.equals. Lew <lewbloch@gmail.com> - 2012-12-18 12:52 -0800
Re: Need clarification on Object.equals. Joshua Cranmer <Pidgeot18@verizon.invalid> - 2012-12-19 09:27 -0600
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 10:44 -0500
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-18 22:11 -0500
Re: Need clarification on Object.equals. Arne Vajhøj <arne@vajhoej.dk> - 2012-12-18 22:10 -0500
csiph-web