I remembered this discussion just today at work when I was faced with the following situation: a method is passed parameters which must not be null and must otherwise be compliant to some validity rules.
So what would authorities recommend: Throw NPE in case of a null argument and IAE in case of other contract violations? This seems confusing to me. Therefore, I am in favor of IAE. Oliver Am 13.05.2014 20:15, schrieb Roger Whitcomb: > Just wanted to mention that the Apache Pivot project (Java GUI framework) > uses IAE for most/all cases of null or invalid input arguments (that is, > cases where we check the input arguments), reserving NPE for basically the > JVM to throw. > > ~Roger Whitcomb > > -----Original Message----- > From: Ralph Goers [mailto:ralph.go...@dslextreme.com] > Sent: Wednesday, May 07, 2014 9:25 PM > To: Commons Developers List > Subject: Re: [lang] > > I have to say that if you look at the JDK for examples of how to code Java > correctly you will be disappointed. There are lots and lots of classes that > are really bad. > > Ralph > > > On May 6, 2014, at 2:54 PM, 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. >> >> >> >> >> 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/NullPointerExcepti >>> on.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
