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From Sébastien Brisard <sebastien.bris...@m4x.org>
Subject Re: [Math] About "NullArgumentException"
Date Wed, 12 Sep 2012 04:46:29 GMT
Hi Phil,

2012/9/10 Phil Steitz <phil.steitz@gmail.com>:
> On 9/10/12 11:47 AM, Sébastien Brisard wrote:
>> Hi
>> What should I do there?
>> I'm trying to work on MATH-854. It turns out that FieldElement<T>.add
>> throws a NAE. Should I catch it below, and rethrow it with a more
>> detailed message (including the entry index)?
>
> IMO, yes.
>
> I would also check v itself and add to the javadoc contract that IAE
> is thrown if v is null.  This is not consistently done in [math],
> though, and rarely in the linear package, so I am OK just letting
> the NPE propagate if v is null.   It is a little awkward that v
> itself being null leads to NPE, but a component of it null leads to
> MIAE.
>
I agree with you, it feels weird. I found a better way: we need to
make sure that entries of FieldVector can *never* be null. This means
checking for null in setters, constructors and the likes. What do you
think?
Sébastien
> Phil
>>
>> Best,
>> Sébastien
>>
>>
>>     /** {@inheritDoc} */
>>     public FieldVector<T> add(FieldVector<T> v)
>>             throws DimensionMismatchException {
>>         try {
>>             return add((ArrayFieldVector<T>) v);
>>         } catch (ClassCastException cce) {
>>             checkVectorDimensions(v);
>>             T[] out = buildArray(data.length);
>>             for (int i = 0; i < data.length; i++) {
>>                 out[i] = data[i].add(v.getEntry(i));
>>                 // SHOULD I CATCH NAE HERE?
>>             }
>>             return new ArrayFieldVector<T>(field, out, false);
>>         }
>>     }


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