Proposal: Collection Literals (original) (raw)

Neal Gafter neal at gafter.com
Tue Mar 31 09:22:57 PDT 2009

On Tue, Mar 31, 2009 at 8:33 AM, Joshua Bloch <jjb at google.com> wrote:

Even if we were to reify generics in a future release, arrays of sets would remain a bad idea. Arrays are covariant and sets are non-variant.  The combination of the two is problematic.  Currently it isn't even typesafe (hence the ban on generic array creation).  With reification of generics, arrays of sets could be made typesafe, but would still admit the possibility of runtime errors that would be caught at compile time if you used List<Set> in place of Set[].

Your comments about arrays interactions with reified types applies to arrays today with ordinary, non-generic types. I understand your desire to provide arrays with less than first-class treatment even with reification and recommend List instead, but I don't think we should be constraining the design space at this time.

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