It's an old debate but the "official" Java coding style has become NPE for null arguments and IAE for invalid non-null arguments. Lang3 was supposed to go down that path because that's how the stewards of Java (Oracle/Sun) are coding and it's part of the best practices found in Joshua Bloch's book.
Cheers, Paul On Tue, May 6, 2014 at 3:50 PM, Duncan Jones <dun...@wortharead.com> wrote: > On 6 May 2014 19:19, Paul Benedict <pbened...@apache.org> wrote: > > NPE is implicit if the method does not allow an argument to be null. This > > doesn't have to be the case. This has nothing to do with the JDK vs. 3rd > > party source. It's just about the contract. As long as you document which > > arguments can be null, then you're good -- otherwise throw an NPE to > > capture the contract violation. > > > > > > Cheers, > > Paul > > I'm strongly in favour of IAE for incorrect null inputs. It makes it > completely clear that the input was validated and found to be lacking. > A NPE tends to make me think something unanticipated has happened. > > I agree with Sebb: NPEs will have people blaming the library before > their own code. > > Duncan > > > > > > > > On Tue, May 6, 2014 at 12:09 PM, sebb <seb...@gmail.com> wrote: > > > >> On 6 May 2014 14:27, Benedikt Ritter <brit...@apache.org> wrote: > >> > 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. > >> > >> +1 > >> > >> > 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. > >> > > >> > >> +1. > >> > >> NPE used to mean a bug had occurred rather than the user had provided > bad > >> input. > >> > >> Using NPE for a parameter that must not be null confuses things. > >> > >> > > >> >> > >> >> 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.". > >> >> > >> > > >> > 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). > >> > >> If Commons ever decide to switch to NPE (I hope not) then it is > >> imperative that the message is 100% clear that the problem is with a > >> method argument, and which argument is at fault. > >> > >> Otherwise we will likely find ourselves fielding bug reports about > >> Commons code when it is the caller that is at fault. > >> Even then, I suspect some reporters will just see the NPE and assume > >> that the Commons code has a bug. > >> > >> If an argument is invalid, throw IAE. > >> IMO it does not make sense to throw NPE for some invalid arguments and > >> not others. > >> What Sun/Oracle perhaps should have done was introduce an > >> "InvalidNullArgumentException" > >> > >> The Javadoc (1.7) says: > >> > >> >>> > >> Thrown when an application attempts to use null in a case where an > >> object is required. These include: > >> > >> Calling the instance method of a null object. > >> Accessing or modifying the field of a null object. > >> Taking the length of null as if it were an array. > >> Accessing or modifying the slots of null as if it were an array. > >> Throwing null as if it were a Throwable value. > >> > >> Applications should throw instances of this class to indicate other > >> illegal uses of the null object. > >> <<< > >> > >> I suppose "illegal use of the null object" could be taken to mean > >> passing null to a non-nullable parameter, but I think that is > >> stretching it too far. > >> > >> > > >> >> > >> >> 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? ;-) > >> > > >> > Regards, > >> > Benedikt > >> > > >> > > >> >> > >> >> My sincere thanks for your time and consideration, > >> >> > >> >> -- > >> >> Thiago Andrade > >> >> > >> > > >> > > >> > > >> > -- > >> > http://people.apache.org/~britter/ > >> > http://www.systemoutprintln.de/ > >> > http://twitter.com/BenediktRitter > >> > http://github.com/britter > >> > >> --------------------------------------------------------------------- > >> 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 > >
