Since this binding occurs late at run-time, this type of polymorphism is known as run-time polymorphism or late binding. Interfaces, Inheritance, and Polymorphism. ![]() ![]() A class written based upon an interface must turn each abstract method into one with a body having the same. The components of an interface are static methods, constants, and abstract methods. If the Log method wasn’t declared as virtual in the base class, the base version of the Log method would have been called instead. An interface is a template for building a Java class. When you execute the above code snippet, the Log method of the derived class, i.e., the Filelogger class would be invoked. The following code snippet shows how the Log method can be called using a reference of the base class. We use method overriding to implement run time polymorphism or late binding. Inheritance and polymorphism are addressed in the following sections. Both the base and the derived classes have the same method with identical signatures. The object-oriented programming (OOP) paradigm is based on three fundamental mechanisms: Encapsulation Inheritance Polymorphism Encapsulation, the focus of Chapter 9, is the language construct that bundles data and methods into a single class specification. The following code snippet shows two classes - the base class named Logger that contains a virtual method called Log and a derived class named FileLogger that extends the Logger class and overrides the Log method of the base class.Ĭonsole.WriteLine("Inside the Log method of the base class Logger") Ĭonsole.WriteLine("Inside the Log method of the FileLogger class") Note that a virtual method is one that is declared as virtual in the base class and you can allow the subclasses of the type to override the virtual method(s). You would typically want to use virtual methods to implement run-time polymorphism or late binding. In method overriding, you have methods having identical signatures present in both the base and the derived classes. Inclusion polymorphism, or method overriding, can be achieved in C# using virtual methods. This is an example of compile time polymorphism. Note how the Log() method has been overloaded. Public void Log(string message, Severity severity) ![]() The following code listing illustrates how method overloading can be implemented. The compiler determines the exact method to be called by comparing the method signatures of the overloaded methods. Hence, a method that accepts an integer and a character as an argument differs in the signature from another method that accepts a character and an integer as arguments even though the return types of both these methods (having identical method names) are the same. A method signature comprises of the return type of the method, the type of the parameters to the method and the sequence of these parameters. This refers to the form of polymorphism where you have more than one method in your class that has the same name but they differ in their method signatures. This ability is also known as specialization. In this type of polymorphism, a sub class can redefine a method of the base class. Inclusion polymorphism is also known as redefinition or method overriding. * The Author class model a book's author.Parametric polymorphism, or template polymorphism, is a type where you have more than one method in your class with identical names but varying parameters, i.e., they all have the same method names, but they differ in the parameters.
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