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From Chris Gray <chris.g...@kiffer.be>
Subject Re: NullPointerException
Date Sun, 19 Mar 2006 15:29:20 GMT
On Friday 17 March 2006 08:47, Anton Avtamonov wrote:

> Actually null-processing and corresponding NPEs are very very often
> omitted from the spec.
> I would say that according to the guidelines Paulex proposed (and as I
> understood we agreed on) we should be RI-compatible in this case.
> Really, spec doesn't say anything regarding null-processing and
> therefore throwing NPE in this case does *not* contradict to the spec.
> Having NPE we will be better RI-compatible and stay on the same
> position in the spec-compatibility (since it is silent).
> Therefore I suggest to be RI-compatible by default in all cases when
> spec keep silence. I believe it well suites Paulex guidelines (please
> correct me if I wrong).


> Talking about how particulary we should throw NPE I'm not sure what to
> advise: in many cases RI just produces them automatically when actual
> call like null.someMehtod() occurs. To provide better notation we can
> do that directly, i.e.
> if (someVar == null) {
>     throw NullPointerException("some valuable message")
> }
> I'm not really sure what is better and would like to know what others
> think about.

I prefer to let these things happen automatically whenever possible. 
Introducing an explicit check adds extra bytecodes and probably extra CPU 
cycles in the non-null case. On some VMs null.someMethod() might be slower in 
the null case, but if the RI also throws NPE then these cases should be truly 
exceptional in the sense that they indicate a programming error or a missing 
resource. OTOH if the RI treats a null argument as a normal case then this 
should be implemented using 'if (someVar == null)', not by catching a NPE(!).


> Btw, when we will work on documentation (javadoc) I think we should
> append references to the standard Sun API in the methods javadoc with
> the direct info about null-processing and NPE if a method can produce
> it (when it is missing from the original spec of course).
> --
> Anton Avtamonov,
> Intel Middleware Products Division

Chris Gray        /k/ Embedded Java Solutions      BE0503765045
Embedded & Mobile Java, OSGi    http://www.k-embedded-java.com/
chris.gray@kiffer.be                             +32 3 216 0369

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