Eric, I know of no oficial documentation explaining this (which does not mean there's none; perhaps I've just missed it).
Some time ago Paul wrote unofficially that a list can be sort of seen as a map from indices to values, and as such, it is expected that non-existing indices return null instead of throwing. The question is whether the technical background (an array can be hardly considered a map, after all) or the polymorphic API (whatever it is, we want that indexing works consistently) should win. Myself I would vote for the latter, but alas I have no idea of the original intention (but for the quoted documentation line, which seems rather to support the latter too). That's why I've asked :) On the other hand, there's at least one more polymorphic indexing available, the one with strings; and in there non-existent indices throw too, quite consistently with arrays. Thanks and all the best, OC > On 6. 2. 2025, at 17:27, Milles, Eric (TR Technology) via dev > <dev@groovy.apache.org> wrote: > > Is there any explicit statement about how indexing beyond the end of a > collection should work? Does it extend the collection or just return null. > Does a withDefault collection do something different? > > In general, arrays and collections should work the same, so the statement in > the working with arrays section is a good one. In the matter of indexing > beyond the end of the array or collection, what is the shared behavior > supposed to be: > > return default value for type — aka null for reference and 0/false for > primitives > throw out-of-bounds exception > something else? > > From: OCsite <o...@ocs.cz <mailto:o...@ocs.cz>> > Sent: Thursday, February 6, 2025 10:11 AM > To: dev@groovy.apache.org <mailto:dev@groovy.apache.org> > <dev@groovy.apache.org <mailto:dev@groovy.apache.org>> > Subject: [EXT] Re: a bug or my fault? > > External Email: Use caution with links and attachments. > > The overall intention is that whether you are using an array or a collection, > the code for working with the aggregate remains the same > <https://urldefense.com/v3/__https://docs.groovy-lang.org/latest/html/documentation/*_working_with_arrays__;Iw!!GFN0sa3rsbfR8OLyAw!ezrONlzs3yG6lC6cFTDF2ASi61brEmoT2ix7QriL2Tg7vhHIhMXTwpPoYFbS77qNBafdycrQlnIZgRDxsA$>. > > In this particular case alas that good and noble intention does not quite > work, and I wonder whether that is intentional (forgive the pun) or a mistake > to be fixed in future, when there's nothing more pressing to do. > > On 6. 2. 2025, at 13:30, Søren Berg Glasius <soe...@glasius.dk > <mailto:soe...@glasius.dk>> wrote: > > You assign 'b' as an Array, and arrays works differently than lists. Arrays > are bound to their length, so 'a[2]' should report out of bounds as it is not > 3 elements long, whereas a list b[2] would report null > > IMO it's working as intended. > > Den tors. 6. feb. 2025 kl. 10.20 skrev OCsite <o...@ocs.cz > <mailto:o...@ocs.cz>>: > Hi there, > > is this inconsistence intentional and the proper Groovy behaviour, or is that > a bug and should I add a jira ticket? > > Thanks! > > === > groovy:000> a=[1,2] > ===> [1, 2] > groovy:000> b=a as Object[] > ===> [1, 2] > groovy:000> a[2] > ===> null > groovy:000> b[2] > ERROR java.lang.ArrayIndexOutOfBoundsException: > Index 2 out of bounds for length 2 > groovy:000> > === > > > -- > > Med venlig hilsen, > Søren Berg Glasius > > Hedevej 1, Gl. Rye, 8680 Ry > Mobile: +45 40 44 91 88 > --- Press ESC once to quit - twice to save the changes.
