Overriding of methods

• We say that we do overriding of a method m() when we define in the subclass a method m() having exactly the same signature as the method m() in the superclass.
• When we do overriding, Java requires that the definition of the new method m() has also the same return type as the original method m(). In other words, the method we are redefining must have the same header as the original method.
• The consequence of overriding is that, each time we invoke the method m() on an object of the derived class D, the method that is effectively called is the one redefined in D, and not the one defined in the base class B, even if the reference used to denote the invocation object is of type B. This behavior is called polymorphism.
• Note that overriding is different from overloading (which is the definition of two methods with the same name but different signatures).