list literal gotcha and suggestion
Mark Thornton
mthornton at optrak.co.uk
Thu Oct 1 12:05:14 PDT 2009
Reinier Zwitserloot wrote:
> For example, instead of stubbornly denying that Set literals aren't as
> important as List literals, can you, as an avid set user, shed some
> light on how acceptable some of the alternative proposals are, such as:
>
> [1, 2, 3].toSet();
>
> new Set[1, 2, 3]; //keep in mind that without the 'new', this syntax
> is pretty much impossible to integrate into the existing java grammar,
> due to looking like an array dereference operation.
>
> new HashSet<>([1, 2, 3]);
>
>
There is another alternative: The value [1,2,3] should be both a List
and a Set while [1, 2, 1] would be just a List. As the elements are
compile time constants the compiler can easily check for duplicates. If
any element appears more than once, then the result is just a List,
otherwise it implements both List and Set.
Regards,
Mark Thornton
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