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From: Jim Janney <jjanney@shell.xmission.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: hashCode
Date: Thu, 30 Aug 2012 08:11:32 -0600
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markspace <-@.> writes:

> On 8/29/2012 1:28 PM, Daniel Pitts wrote:
>>
>> The point is that hashing "Object" isn't entirely sensible in most
>> situations.
>
> Why not?  I do it all the time.  Put an object in, get an object
> out. Works great.

I've worked on code that failed in mysterious ways because someone used
a HashMap assuming object identity, and then, a few years later, someone
else defined equals on one of the subclasses.  If you need identity
semantics, use java.util.IdentityHashMap: that's what it's for.

In practice, when I use HashMap the keys are almost always Strings, or
else classes designed for use as keys.

-- 
Jim Janney