New to Java

Hi;

I have a method in a class that should pass an object of class type "old"
and I want the modified object of this class to be used,
i.e., the object to be used should be of type "new" in the new.java
where classmethod.java should use (x :old) in the method needed.


here; i need to invoke the method "method()" in the file new.java as follows

method(this);

but in the implementation of "method()" (in classmethod.java) I want to use the object of type "old".

how could i do tha casting?

i did this in classmethod.java


contrsuctormethod( new a){
method ((old) a);
}

but it gives me an error
(inconvertable types)
how could I solve this?