I think you want something like this:
public class Person {
private int age;
//public method to get the age variable
public int getAge(){
return this.age
}
//public method to set the age variable
public void setAge(int age){
this.age = age;
}
}
You're simply calling such a method on an object instance. Such methods are useful especially if setting something is supposed to have side effects. E.g. if you want to react to certain events like:
public void setAge(int age){
this.age = age;
double averageCigarettesPerYear = this.smokedCigarettes * 1.0 / age;
if(averageCigarettesPerYear >= 7300.0) {
this.eventBus.fire(new PersonSmokesTooMuchEvent(this));
}
}
Of course this can be dangerous if somebody forgets to call setAge(int) where he should and sets age directly using this.age.