Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!aioe.org!eternal-september.org!feeder.eternal-september.org!.POSTED!not-for-mail
From: markspace <-@.>
Newsgroups: comp.lang.java.programmer
Subject: Re: Did the sort do anything?
Date: Tue, 17 May 2011 07:41:49 -0700
Organization: A noiseless patient Spider
Lines: 28
Message-ID: <iqu1fj$jvq$1@dont-email.me>
References: <eskis656eeu0of5f5do1ogdpfbdau3d06i@4ax.com> <9303hcFq0nU1@mid.individual.net> <iqgrhp$fh7$1@dont-email.me> <jsgqs61b31jq07e1tmr7d910rfacjeok5r@4ax.com> <iqq2b2$jhm$4@lust.ihug.co.nz> <N6-dnSCv9viQDE3QnZ2dnUVZ_v6dnZ2d@earthlink.com> <iqqec4$qi7$2@lust.ihug.co.nz> <kemdnZVnBva8n0zQnZ2dnUVZ_uqdnZ2d@earthlink.com> <iqr3nv$6t5$2@lust.ihug.co.nz> <noidndppmuNYrEzQnZ2dnUVZ_gednZ2d@earthlink.com> <iqs3tn$pqm$2@lust.ihug.co.nz>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Injection-Date: Tue, 17 May 2011 14:41:56 +0000 (UTC)
Injection-Info: mx04.eternal-september.org; posting-host="HywFvwzxyTvAIJCzdmb/Mw"; logging-data="20474"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX18KYCKPrrnrNQVrHiMepHy2yC9G56BYpHk="
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.17) Gecko/20110414 Thunderbird/3.1.10
In-Reply-To: <iqs3tn$pqm$2@lust.ihug.co.nz>
Cancel-Lock: sha1:62sZQWtI6d1wj4YHcAf6ssmtloU=
Xref: x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:4216

On 5/16/2011 2:11 PM, Lawrence D'Oliveiro wrote:
> In message<noidndppmuNYrEzQnZ2dnUVZ_gednZ2d@earthlink.com>, Patricia
> Shanahan wrote:
>
>> System.identityHashCode(x) does not necessarily return the same as
>> x.hashCode() ...
>
> It says it does
> <http://developer.android.com/reference/java/lang/System.html#identityHashCode%28java.lang.Object%29>:
>
>  The hash code returned is the same one that would be returned by
> the method java.lang.Object.hashCode(), whether or not the object's
> class has overridden hashCode().

Ouch, no.  Newbie maneuver.

Lots of info on this, but if you override equals(), you must override
hashCode() because Object#hashCode() will not have the right semantics.
  Basically, in this case Object#hashCode() will return different hash
codes for objects that compare equals() == true, and that breaks the
contract.


> Which brings us back to the point I made before, about whether the
> sort key is computed from the entire value or not.


Depends on the Comparator you are using.