Code review request for 6891113: More methods for java.util.Objects: deepEquals, hash, toString with default

[Joe Darcy]

Neal Gafter wrote:
> There should be a shortcut in Arrays.deepEquals0 when e1==e2.  

That shortcut is in Objects.deepEquals(Object a, Object b) and 
Arrays.deepEquals on lines 3947 and 3948.  The nested call in 
deepEquals0 is to deepEquals rather than deepEquals0 so the shortcut is 
used on all levels.

> Also, the code will throw an assertion error if e1!=null and e2==null 
> (which can occur when called from Arrays.deepEquals).

Good catch!  Yes, my mistake; only e1 != null is guaranteed when being 
called from Arrays.deepEquals.

> The simplest way to fix these is to move the if statements from 
> Objects.deepEquals into Arrays.deepEquals0.  Alternately, change the 
> call of Arrays.deepEquals0 in Arrays.deepEquals to a call to 
> Objects.deepEquals.  If you do the latter, you might as well move all 
> the code of deepEquals0 into the body of Object.deepEquals.

For correctness, I think removing the assertion that e2 != null in 
deepEquals0 is sufficient.

Thanks,

-Joe

>
> Cheers,
> Neal
>
> On Wed, Oct 21, 2009 at 5:24 PM, Joseph D. Darcy <Joe.Darcy at sun.com 
> <mailto:Joe.Darcy at sun.com>> wrote:
>
>     Hello.
>
>     Please review this webrev to add deepEquals(Object, Object),
>     hash(Object...) and toString(Object, String) to j.u.Objects:
>
>     6891113 More methods for java.util.Objects: deepEquals, hash,
>     toString with default
>     http://cr.openjdk.java.net/~darcy/6891113.0/
>     <http://cr.openjdk.java.net/%7Edarcy/6891113.0/>
>
>     Thanks,
>
>     -Joe
>
>