Multi-state upward transformation downward transformation

     Public Static void Main (string[] args) {        Artist Artist;         New Violinartist (); // Violinartist (UP) is a subclass, and the parent class refers to a subclass object that loses its own unique properties and methods        Artist.make (); //         methods for calling subclasses // Artist.play ();   Will error,        new  violinartist ();

if instanceof violinartist) {//Determine if an object belongs to a class or an interface            System.out.println ("true");        } Else {            System.out.println ("false");        }

        = (violinartist) artist; // transform down to restore your own unique methods and properties         Va.play ();    }

Multi-state upward transformation downward transformation