On 13 May 2014 02:02, Phil Steitz <phil.ste...@gmail.com> wrote: > > >> On May 6, 2014, at 10:51 PM, Duncan Jones <dun...@wortharead.com> wrote: >> >>> On 7 May 2014 01:52, "Paul Benedict" <pbened...@apache.org> wrote: >>> >>> When you dereference a null pointer, you get an NPE. We can agree to that. >>> We can also agree it's not inherently wrong to throw IAE on a null >> argument >>> check, but this discussion has never been about that. The discussion has >>> always centered on what the trend setters are doing -- and they say go >> with >>> NPE. >>> >>> Oracle/Sun throws NPE in its method: >> http://docs.oracle.com/javase/7/docs/api/java/util/Objects.html#requireNonNull%28T%29 >>> >>> Google Guava throws NPE in its method: >> http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/Preconditions.html#checkNotNull%28T%29 >>> >>> It's pretty clear where industry is going and not using NPE is not >>> expected. We shouldn't try to resist where all the thought leaders in our >>> industry are going. It doesn't make any sense. No matter what personal >>> affinity/preference you have towards IAE, it's a losing battle because the >>> march is going the other direction. >> >> This is a very compelling point. We don't want to alienate our user base >> because a handful of us believe the Java community is going in the wrong >> direction. >> >> I could be swayed by that argument alone. We hardly need more reasons for >> people to consider Lang to be outdated compared with Guava etc. > > Interesting how I see that argument as exactly the opposite - ie if the only > "argument" in support of a technical decision is "that's where things are > going" I see that as a good reason not to capitulate. The best thing about > OSS (at least how we have traditionally done it here @apache) is we make > technical decisions based on technical arguments and the people who actually > contribute to the code get listened to. So instead of vague references to > "thought leaders" or what others are doing, what matters is what arguments > are presented here. In this thread, I have yet to see a good argument for > tossing npe when an API advertises parm checking. Do you have one? Does > anyone else?
I have no technical arguments to present - IAE is the only sensible technical option. I quite like your opinion that we should pave the way with what we think is correct behaviour. I'm firmly back in the IAE camp, I think. On a similar subject, I note that the Validate.validIndex() methods throw IndexOutOfBoundsException. I see this as the same argument as NPE - we should throw IAE instead, since IOOBE is similarly a "something went wrong" exception, rather than a validation exception. Duncan > > Phil >> >>> >>> Paul >>> >>> >>> Cheers, >>> Paul >>> >>> >>>> On Tue, May 6, 2014 at 6:27 PM, sebb <seb...@gmail.com> wrote: >>>> >>>>> On 6 May 2014 22:54, Paul Benedict <pbened...@apache.org> wrote: >>>>> This is not a matter of law. If Oracle/Sun set a direction on how to >> use >>>>> NPE, it's a really good idea to follow them -- even if you don't >> agree, >>>> do >>>>> it for the sake of consistency. I don't think using IAE is somehow >>>> "better" >>>>> Java than what they are doing. And I give weight to what Joshua said >>>>> because he's a former architect of that company. Lang3 was designed to >>>>> throw NPE on invalid null arguments because that's what the gurus, >> like >>>> he, >>>>> in our industry who publish "best practices" say it should. If your >>>> opinion >>>>> bears greater weight than those set forth the best practices, then you >>>> win, >>>>> but I don't advocate going back to IAE for nulls for the reasons >> stated. >>>> >>>> The problem is still that NPE can be thrown by the JVM for code bugs. >>>> If you Google/Bing for "what does NPE mean?" most of the postings say >>>> that this is due to a bug in the code that throws it rather than a bug >>>> in the code that calls it. >>>> >>>> There is nothing inherently wrong with using IAE for reporting a null >>>> argument. >>>> I think it was a mistake to suggest using NPE for that. >>>> One might as well throw ArithmeticException for a zero argument that >>>> is going to be used as a divisor. >>>> Neither is as helpful as IAE. >>>> >>>> The problem is that NPE is ambiguous. IAE is not. >>>> >>>>> >>>>> >>>>> >>>>> Cheers, >>>>> Paul >>>>> >>>>> >>>>>> On Tue, May 6, 2014 at 4:40 PM, Duncan Jones <dun...@wortharead.com> >>>>> wrote: >>>>> >>>>>>> On 6 May 2014 22:27, "Michael Osipov" <1983-01...@gmx.net> wrote: >>>>>>> >>>>>>> Am 2014-05-06 15:27, schrieb Benedikt Ritter: >>>>>>> >>>>>>>> Hi Thiago, >>>>>>>> >>>>>>>> >>>>>>>> 2014-05-06 14:53 GMT+02:00 Thiago Andrade <thia...@gmail.com>: >>>>>>>> >>>>>>>>> Hello people, >>>>>>>>> >>>>>>>>> Analizing the JIRA issue >>>>>> https://issues.apache.org/jira/browse/LANG-1008the >>>>>>>>> contributors noticed that NumberUtils.max/min methods all have >> the >>>> same >>>>>>>>> problem: >>>>>>>>> They all throw an IllegalArgumentException when according to the >>>>>> official >>>>>>>>> documentation (Oracle|Sun) says that a NullPointerException must >> be >>>>>> thrown >>>>>>>>> when an argument must not be null. >>>>>>>> >>>>>>>> This is not a problem imho. It is a question of API design. I >> don't >>>> now >>>>>> an >>>>>>>> offical documentation that say when IAE or NPE _must_ be thrown. >>>>>> Sun/Oracle >>>>>>>> at some point decided to throw NPE when ever a null reference is >>>> passed >>>>>> to >>>>>>>> a method that doesn't accept null inputs. I don't feel this is >> right, >>>>>> since >>>>>>>> a null input is also an illegal argument. Why make a >> differenciation? >>>>>> IMHO >>>>>>>> NPE should be reserved to the JVM, when a method is called on a >> null >>>>>>>> reference, but that's just my opinion. >>>>>>> >>>>>>> >>>>>>> It *is* a problem because NullPointerException and >>>>>> IllegalArgumentException have concrete semantics layed out in the >> JDK's >>>>>> Javadocs. If you see how both are used in the JDK, you see that NPE >> and >>>> IAE >>>>>> are used properly and there is no such restriction to the JDK only. >> If >>>> you >>>>>> aread Effective Java, you'll see that you *have to* use NPE if a null >>>>>> argument is passed. One might remember the NullArgumentException >> back in >>>>>> Lang 2, it was removed because it is imperative to use NPE instead. >>>>>> >>>>>> Effective Java is a great book, but don't confuse Joshua's advice >> with >>>> law. >>>>>> >>>>>>> >>>>>>> Moreover, the Lang 3 package includes a great class, Validate, >> which >>>> does >>>>>> things right and now I can ask, why the hell is that not used >> throughout >>>>>> the entire library? >>>>>> >>>>>> +1 to this. We should update all of lang to use Validate once we've >>>> nailed >>>>>> this issue. >>>>>> >>>>>> Duncan >>>>>> >>>>>>> >>>>>>> >>>>>>>>> However according to Apache Commons Lang Developer Guide, these >>>> methods >>>>>> are >>>>>>>>> all correct. This guide says that "When throwing an exception to >>>>>> indicate a >>>>>>>>> bad argument, always try to throw IllegalArgumentException, even >> if >>>> the >>>>>>>>> argument was null. Do not throw NullPointerException.". >>>>>>> >>>>>>> >>>>>>> Correct to the dev guide only -- not Java. >>>>>>> >>>>>>> >>>>>>>> Since [lang] is currently designed this way, I'd rather deal with >>>> this >>>>>>>> issue for 4.0. We can then revisit our initial decision to only >> throw >>>>>> IAE >>>>>>>> an maybe align it to what the JDK now does. If you want to file an >>>>>> issue, >>>>>>>> my opinion is, that it should be fix version 4.0. Changing the >>>>>> exceptions >>>>>>>> that are thrown now may break clients (although I think there are >>>> very >>>>>> few >>>>>>>> use cases where one should catch IAE or NPE). >>>>>>> >>>>>>> >>>>>>> 4.0 has to use Validate throughout the entire package. NPE and IAE >>>>>> indicate a programming error in the client not adhering to the >> contract >>>>>> depicted by the Javadocs, so it is the client's problem to deal with >>>> them. >>>>>> With proper programming, you should not have to catch those >> exception at >>>>>> all. >>>>>>> >>>>>>> >>>>>>>>> This mail was sent in order to discuss around and make decisions >> to >>>>>> solve >>>>>>>>> this dilemma where the Java official specification says X and the >>>>>> Apache >>>>>>>>> official specification says Y. >>>>>>>> >>>>>>>> Can you please provide a lnk to the official specification you're >>>>>> refering >>>>>>>> to? ;-) >>>>>>> >>>>>>> >>>>>>> Read Effective Java on exceptions. Thiago provided a URL in the >> JIRA >>>>>> issue. >>>>>>> >>>>>>> Further good resources: >>>>>>> >>>>>>> 1. >> http://docs.oracle.com/javase/7/docs/api/java/lang/NullPointerException.html >>>>>>> 2. >>>> http://docs.oracle.com/javase/tutorial/essential/exceptions/runtime.html >> : >>>>>> "One case where it is common practice to throw a RuntimeException is >>>> when >>>>>> the user calls a method incorrectly. For example, a method can check >> if >>>> one >>>>>> of its arguments is incorrectly null. If an argument is null, the >> method >>>>>> might throw a NullPointerException, which is an unchecked exception." >>>>>>> >>>>>>> Michael >> --------------------------------------------------------------------- >>>>>>> To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org >>>>>>> For additional commands, e-mail: dev-h...@commons.apache.org >>>> >>>> --------------------------------------------------------------------- >>>> To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org >>>> For additional commands, e-mail: dev-h...@commons.apache.org >>>> >>>> > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org > For additional commands, e-mail: dev-h...@commons.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
