On 7 May 2014 01:51, 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.
None of that alters the fact the using NPE in this way is ambiguous. Whereas IAE is not. > 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
