Variables are named as variables because their value can vary. Be it private variables or public. Private variablesâ values are not changed directly and this job is trusted to public methods instead that the class exposes.
What are you trying to ask here in not very clear though, because whenever you use a class you change the values of the private variables of that class (if there exist any) through method calls almost always. So please be specific as to what it is that you actually wanna ask.