Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!news.glorb.com!news-out.readnews.com!transit4.readnews.com!news-out.news.tds.net!newsreading01.news.tds.net!53ab2750!not-for-mail
From: "Arne Vajhøj" <arne.vajhøj@1:261/38.remove-t9h-this>
Subject: Re: hashCode
Message-ID: <50254C54.56595.calajapr@time.synchro.net>
X-Comment-To: markspace
Newsgroups: comp.lang.java.programmer
In-Reply-To: <50254C54.56594.calajapr@time.synchro.net>
References: <50254C54.56594.calajapr@time.synchro.net>
X-FTN-AREA: COMP.LANG.JAVA.PROGRAMMER
X-FTN-MSGID: 1:261/38 6cc297ff
X-FTN-REPLY: 1:261/38 633471b9
Content-Type: text/plain; charset=IBM437
Content-Transfer-Encoding: 8bit
X-Gateway: time.synchro.net [Synchronet 3.16a-Win32 NewsLink 1.98]
Lines: 39
Date: Fri, 10 Aug 2012 18:39:06 GMT
NNTP-Posting-Host: 69.21.70.65
X-Complaints-To: news@tds.net
X-Trace: newsreading01.news.tds.net 1344623946 69.21.70.65 (Fri, 10 Aug 2012 13:39:06 CDT)
NNTP-Posting-Date: Fri, 10 Aug 2012 13:39:06 CDT
Organization: tds.net
Xref: csiph.com comp.lang.java.programmer:17649

  To: markspace
From: Arne Vajhoj <arne@vajhoej.dk>

On 8/10/2012 1:13 PM, markspace wrote:
> On 8/10/2012 9:13 AM, Arne Vajhoj wrote:
>> On 8/10/2012 11:47 AM, bob smith wrote:
>>> Is it always technically correct to override the hashCode function
>>> like so:
>>>
>>>     @Override
>>>     public int hashCode() {
>>>         return 1;
>>>     }
>>
>> It meets the minimum contractual obligation for that method.
>>
>> But performance of anything using the hash capability (like HashMap<>)
>> would be very bad.
>>
>>> Would it be potentially better if that was Object's implementation?
>>
>> It has a different behavior that may not be valid if you override equals.
>
> I think at this point we are doing Bob's homework for him.

Could be.

But I think the question whether returning a constant from hashCode is a valid 
Java question for understanding the contract for that method.

And I am pretty sure that I have seen other similar examples (just with 42 as 
constant).

Arne

--- BBBS/Li6 v4.10 Dada-1
 * Origin: Prism bbs (1:261/38)
--- Synchronet 3.16a-Win32 NewsLink 1.98
Time Warp of the Future BBS - telnet://time.synchro.net:24