Is there a way to toss a filename to MS Windows (from a Java application),
invoking Windows to open the application registered with the particular file
type (e.g. MS Word for a .doc file, the default browser for a .html file,
...) with the particular file opnened?

Invoking a particular Windows application with Runtime.exec() is no problem,
but I cannot assume the filetype nor which application to use (and where
it is located) known.