🚀 go-pugleaf

I'd like to be able to build a JTree using models that are loaded by
passing the model name.  The basic idea is to instantiate an instance
variable of the interface that all the models implement in a separate
class, and then use the interface methods to build the tree without ever
knowing in advance which tree will be built. My problem is that I can't
seem to use the (interface)Class.forname("classname").newInstance() and
get anything other than null. The other complication is that the models
take parameters but I think I could handle this with a separate
interface function as opposed to through a constructor. My thought was
that if I have trees which can take variable models it would good
practice to make those trees pluggable. I would appreciate any help on
how to use the forname/instanceof construction or if I 've got something
wrong in how I'm conceving this. Thanks.