Hi, My experience with NullPointerExceptions in Geotools suggest that better Javadocs could make a huge difference.
The hard part isn't to find why or where you get an NullPointerException. That will be clear from the stack trace. The hard part is often to figure out how to properly set the value of a variable to avoid it being null. "Where did that come from?", is a question that often pop up. This would be easier to answer if the documentation expressly says what to expect for the different parameters, especially when null is disallowed. Also when a method are using instance variable that shouldn't be null. It would be nice if the documentation says something about how to set it. I do see that a approach with annotation and a library that check the code at compilation, would be as good as using Optionals. As Geotools are using SpotBugs, I suppose that would be the best candidate to look into. At first glance I couldn't figure out how to do to though. If anyone could give me some directions, I wouldn't mind having a deeper look at it. Best regards, Roar Brænden > 12. jun. 2021 kl. 19:04 skrev Andrea Aime <andrea.a...@geo-solutions.it>: > > Hi, > I'm starting a new thread as Roar raised some interest was raised in null > handling/elimination > in the "cognitive complexity" thread (to avoid derailing it, and giving a > good place to this discussion). > > Roar suggestd the usage of Optional... it's a way, has some drawbacks, like > API break, > using it in the right place, cost of wrapper creation, and so on. Again, some > references: > - > https://medium.com/@yassinhajaj/optionals-are-bad-practices-still-bad-practices-if-everyone-practices-them-6ec5a66c30aa > > <https://medium.com/@yassinhajaj/optionals-are-bad-practices-still-bad-practices-if-everyone-practices-them-6ec5a66c30aa> > - https://dzone.com/articles/using-optional-correctly-is-not-optional > <https://dzone.com/articles/using-optional-correctly-is-not-optional> > > I was wondering about other tools too, like: > - NullAway, a dedicated library by Uber, which builds on top of ErrorProne > and adds null checks (nothing is nullable unless expressly annotated): > https://github.com/uber/NullAway <https://github.com/uber/NullAway> > - SpotBugs CheckForNull annotation > <https://github.com/spotbugs/spotbugs/blob/master/spotbugs-annotations/src/main/java/edu/umd/cs/findbugs/annotations/CheckForNull.java#L26> > (not 100% sure how it's supposed to be used) > - Some discussion about non null checkers, along with more about Optional > usage, here <https://checkerframework.org/manual/#nullness-related-work> > > The reason I'd suggest looking at those, is that they would not cause an API > break, > actually detect at least some of the issues, and avoid some of the issues > with Optional > > Anyways, just thinking out loud, won't commit my time on this (at least in > the short term). > Hope that somebody else will though :-D > > Cheers > Andrea > > == > GeoServer Professional Services from the experts! Visit http://goo.gl/it488V > <http://goo.gl/it488V> for more information. > == > > Ing. Andrea Aime > @geowolf > Technical Lead > > GeoSolutions S.A.S. > Via di Montramito 3/A > 55054 Massarosa (LU) > phone: +39 0584 962313 > fax: +39 0584 1660272 > mob: +39 339 8844549 > > http://www.geo-solutions.it <http://www.geo-solutions.it/> > http://twitter.com/geosolutions_it <http://twitter.com/geosolutions_it> > > > ------------------------------------------------------- > > Con riferimento alla normativa sul trattamento dei dati personali (Reg. UE > 2016/679 - Regolamento generale sulla protezione dei dati “GDPR”), si precisa > che ogni circostanza inerente alla presente email (il suo contenuto, gli > eventuali allegati, etc.) è un dato la cui conoscenza è riservata al/i solo/i > destinatario/i indicati dallo scrivente. Se il messaggio Le è giunto per > errore, è tenuta/o a cancellarlo, ogni altra operazione è illecita. Le sarei > comunque grato se potesse darmene notizia. > > This email is intended only for the person or entity to which it is addressed > and may contain information that is privileged, confidential or otherwise > protected from disclosure. We remind that - as provided by European > Regulation 2016/679 “GDPR” - copying, dissemination or use of this e-mail or > the information herein by anyone other than the intended recipient is > prohibited. If you have received this email by mistake, please notify us > immediately by telephone or e-mail. > _______________________________________________ > GeoTools-Devel mailing list > GeoTools-Devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/geotools-devel
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