What I think you are saying is that you want to dynamically create a
variable at runtime of type int and maybe even give it a value. You can not
extend the members of a class or method at runtime like that, however if you
need to assign a value to a variable and you don't know the type until the
program is running then assign it an object to start with and at runtime
convert the object to the appropriate datatype on the fly.

//Design time Example.

Object unknownType = null;

//Runtime example:

int = ((Integer) unknownType).intValue;