On Fri, Aug 30, 2013 at 10:30 AM, sebb <seb...@gmail.com> wrote:
> On 30 August 2013 15:19, Benedikt Ritter <brit...@apache.org> wrote:
> > I've removed the generics in r1518974, thanks for spotting that sebb.
> >
> > Regarding the exception to throw I'm indifferent. The important thing is
> to
> > fail early.
> >
>
> ... and with a helpful message.
>
> > I personally thing that NPE should be reserved for signaling that some
> code
> > tried to invoke a method on a null reference.
>
> +1
>
> > In our case null is illegal because we know that some code later on would
> > break if we accept a null reference. So IllegalStateException makes
> sense.
>
> s/IllegalStateException /IllegalArgumentException/
>
> +1
>
> > Imaging having a method that accepts an int and only positive ints are
> > valid. You would throw an IllegalArgumentException if a negative int is
> > passed to that method and not a NegativeIntegerException (or what ever).
> > But James has a point. If [LANG] uses NPE maybe we should stick to this.
>
> I don't think we have to do the same as LANG, so long as the Javadoc is
> clear.
>
> > Feel free to change it. I'll leave it for now since there doesn't seem to
> > be consensus?!
>
> Unless there are other reasons than "LANG happens to use NPE" I think
> we should stick with IAE, as it more clearly indicates the the problem
> is not within the method throwing it.
>
> The problem with using NPE to flag parameter errors is that it
> confuses the user as to the likely cause.
>
> Leave NPEs to the runtime system.
>
I agree with all of Sebb's +1 and arguments.
Gary
>
> > Benedikt
> >
> >
> > 2013/8/30 James Carman <ja...@carmanconsulting.com>
> >
> >> Well, the problem with using NPE is that we as Java developers have
> >> learned through the years that NPE typically is an "oh crap"
> >> situation, where something is terribly wrong (we hate seeing those).
> >> Thus, our users may have knee-jerk reactions and not even know to
> >> inspect the message for the real cause. IAE is less alarming, IMHO.
> >> Just my $0.02, but we've been doing it that way for a long time in
> >> [lang], so be it.
> >>
> >>
> >> On Fri, Aug 30, 2013 at 9:01 AM, sebb <seb...@gmail.com> wrote:
> >> > AFAIK "accidental" NPEs don't have a message associated with them.
> >> >
> >> > So provided that the assertion generates the NPE with a suitable
> >> > message (e.g.as currently done for the IAE) then it *should* be
> >> > possible for the end user to distinguish the two cases.
> >> >
> >> > I am slightly in favour of retaining IAE as the cause is obvious with
> >> > needing to look at the NPE message.
> >> >
> >> > ==
> >> >
> >> > Horrible hack: - if you want to use NPE, you could wrap an IAE in the
> >> NPE:
> >> >
> >> > npe = new NPE(msg);
> >> > npe.initCause(new IAE(msg));
> >> > throw npe;
> >> >
> >> > Or vice-vera, of course!
> >> >
> >> > Not sure that gains anything, but it does make the stack trace look
> >> > more impressive!
> >> >
> >> > On 30 August 2013 13:42, James Carman <ja...@carmanconsulting.com>
> >> wrote:
> >> >> Commons Lang's Validate.notNull() throws NPEs. I don't know that
> I've
> >> >> necessarily agreed with that, but at some point a decision was made
> >> >> that null constraint violations should throw NPEs. Food for thought.
> >> >>
> >> >> On Fri, Aug 30, 2013 at 8:32 AM, Gary Gregory <
> garydgreg...@gmail.com>
> >> wrote:
> >> >>> On Fri, Aug 30, 2013 at 8:25 AM, Emmanuel Bourg <ebo...@apache.org>
> >> wrote:
> >> >>>
> >> >>>>
> >> >>>> >> + if (parameter == null) {
> >> >>>> >> + throw new IllegalArgumentException("Parameter '" +
> >> >>>> parameterName + "' must not be null!");
> >> >>>> >> + }
> >> >>>> >> + }
> >> >>>> >> +}
> >> >>>>
> >> >>>> Isn't a null value supposed to throw a NPE ?
> >> >>>>
> >> >>>
> >> >>> Not always IMO. When I see an NPE I assume something is very wrong
> and
> >> that
> >> >>> it could be a bug in the impl OR a call site, somewhere on the code
> >> path.
> >> >>>
> >> >>> With an IAE, I know for sure it's a problem in the call site (which
> >> could
> >> >>> be a bug of course).
> >> >>>
> >> >>> I does not help that the JRE/JDK is inconsistent, so it's hard to
> find
> >> >>> examples.
> >> >>>
> >> >>> Gary
> >> >>>
> >> >>>
> >> >>>> Emmanuel Bourg
> >> >>>>
> >> >>>>
> >> >>>>
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> >> >>>>
> >> >>>>
> >> >>>
> >> >>>
> >> >>> --
> >> >>> E-Mail: garydgreg...@gmail.com | ggreg...@apache.org
> >> >>> Java Persistence with Hibernate, Second Edition<
> >> http://www.manning.com/bauer3/>
> >> >>> JUnit in Action, Second Edition <http://www.manning.com/tahchiev/>
> >> >>> Spring Batch in Action <http://www.manning.com/templier/>
> >> >>> Blog: http://garygregory.wordpress.com
> >> >>> Home: http://garygregory.com/
> >> >>> Tweet! http://twitter.com/GaryGregory
> >> >>
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> >> >
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> >>
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> >>
> >
> >
> > --
> > http://people.apache.org/~britter/
> > http://www.systemoutprintln.de/
> > http://twitter.com/BenediktRitter
> > http://github.com/britter
>
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--
E-Mail: garydgreg...@gmail.com | ggreg...@apache.org
Java Persistence with Hibernate, Second Edition<http://www.manning.com/bauer3/>
JUnit in Action, Second Edition <http://www.manning.com/tahchiev/>
Spring Batch in Action <http://www.manning.com/templier/>
Blog: http://garygregory.wordpress.com
Home: http://garygregory.com/
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