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 We hardly need more reasons for people to consider Lang to be outdated compared with Guava etc. > > 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 > > > >
