Superclass reference to subclass object showing same behaviour as subclass reference to subclass object

Question

The following code in java, when run on elipse, gives same output even if we replace

superclass s=new sub();

with,

sub s= n         


        

Answer 1

let's take an example: sup is a reference variable for a class A's objects. and sub is a reference variable for a class B's objects. let's suppose B extends A . so if we write "sup = sub;" or "sup = new B();" this statement enables us to get the attributes that are common between the 2 classes . i.e : the attributes that were inherited by B ... we use this trick to check for attributes inherited by B and were changed.