Understanding Method Overriding, Polymorphism, Abstract Classes and interface in Java

In this lecture, we'll delve into the more concepts of object-oriented programming (OOP) in Java: method overriding, polymorphism, abstract classes, abstract methods, and interfaces. These concepts are essential for building robust and maintainable software.

Method Overriding is a mechanism where a subclass provides a specific implementation for a method inherited from its superclass. This allows for customization and flexibility in the behavior of objects. When a method is called on a reference variable, the actual implementation executed depends on the object's runtime type.

Polymorphism is the ability of objects to take on multiple forms. It's a fundamental principle of OOP that enables code to be more flexible and reusable. There are two main types of polymorphism:

Compile-time polymorphism: Achieved through method overloading, where multiple methods with the same name but different parameters exist within a class. The compiler determines the appropriate method to call based on the arguments provided.

Runtime polymorphism: Also known as dynamic binding or late binding, it occurs when the actual method to be executed is determined at runtime based on the object's type. This is made possible through method overriding.

Abstract Classes are classes that cannot be instantiated directly. They serve as templates for other classes and often contain abstract methods. Abstract methods are methods declared without a body. They must be implemented by any concrete subclass that extends the abstract class. Abstract classes are useful for defining common behaviors and properties that can be shared by related classes.

Interfaces are similar to abstract classes but provide a more restrictive contract for implementing classes. They can only contain abstract methods and constant declarations. Interfaces are used to define a set of related methods that classes must implement to conform to a particular behavior. Multiple inheritance is possible through interfaces, allowing a class to implement multiple interfaces.