Understanding Polymorphism and Inheritance in Java with Examples

Generated with sparks and insights from 14 sources

Introduction

Inheritance in Java: allows one class to inherit the fields and methods of another class using the keyword 'extends'.
Polymorphism in Java: refers to the ability of a method to perform differently based on the object type, essential for achieving flexible code.
Types of Polymorphism: includes compile-time polymorphism (method overloading) and runtime polymorphism (method overriding).
Method Overriding: involves a subclass providing a specific implementation of a method defined in its superclass.
Method Overloading: allows multiple methods with the same name to exist, each with different parameters.

Definition: Inheritance allows a child class to inherit traits and methods from a parent class using the 'extends' keyword.
Class Structure: Child classes inherit all public and protected variables and methods from the parent class.
Method Example: A Dog class could extend an Animal class, inheriting properties like 'sound'.
Benefits: Reduces redundancy, promotes code reuse, and simplifies maintenance.
Keyword Usage: 'super()' is used to call the parent class constructor from the child class.

Definition: Polymorphism allows methods to perform differently based on the object class that calls them.
Examples: Different objects call the same superclass method but execute unique subclass implementations.
Real-life Illustration: A person acts as a parent and employee, showing different behaviors in different contexts.
Significance: Enhances flexibility in code design, allows objects of different types to share the same interface.
Application: Commonly used in design patterns to decouple the client class from implementation code.

Compile-time Polymorphism: Achieved through method overloading, enabling multiple methods with the same name but different parameters.
Runtime Polymorphism: Method overriding where a subclass implements a method from the parent class, the execution depends on the object type at runtime.
Operator Overloading: Not supported in Java, occurring in other languages where operators can work differently based on operands.
Polymorphic Variables: Variables that can hold values of different types during execution, promoting flexibility.
Subtype Polymorphism: Allows generic methods to be executed on various types sharing a common superclass.

Concept: Allows a subclass or child class to provide a specific implementation of a method that is already provided by one of its superclasses or parent classes.
Purpose: Enables different versions of a method to be called depending on the object instance, adding flexibility.
Keyword: Use '@Override' to indicate the method is overriding a method from a superclass.
Example: Environmental sounds in a generic 'Animal' class can be overridden in 'Dog', 'Cat', etc.
Restrictions: Parameters must be identical to the parent class method to override successfully.

Definition: The ability to define multiple methods with the same name differentiated by parameter types and numbers.
Purpose: Provides different ways to perform an action while maintaining the same method name.
Example: Calculate area with different parameters in Shape class for circles, squares, triangles, etc.
Usage: Compile-time polymorphism where the method called is determined at compile-time.
Benefits: Enhances readability and reduces complexity by having multiple behaviors with the same method name.