[Haskell-cafe] Re: What I wish someone had told me...
robgreayer at yahoo.com
Thu Oct 16 13:02:13 EDT 2008
--- On Thu, 10/16/08, Jonathan Cast <jonathanccast at fastmail.fm> wrote:
> Can I have HashSet<Integer>? Could I construct
> HashSet<?>, if I did?
HashSet<?> blah = (HashSet<?>) hashSetClass.newInstance();
... compiles, and won't throw an exception if hashSetClass truly is the class object for HashSet. Pretty useless, because you can't put anything *into* a HashSet<?> object...
blah.add("foo"); // doesn't typecheck...
but you can do:
HashSet<String> blah = (HashSet<String>) hashSetClass.newInstance();
More information about the Haskell-Cafe