Object-Oriented Programming (OOP) in Java and Kotlin with Android Use Cases

Introduction

Object-Oriented Programming (OOP) allows you to structure your code using real-world entities like objects and classes.

It makes code modular, reusable, and scalable—all of which are critical in Android app development.

We'll explore:

• The four OOP pillars (Encapsulation, Inheritance, Polymorphism, Abstraction)
• Each type (compile-time/runtime polymorphism, abstract/interface, etc.)
• Java vs Kotlin examples
• Real-world Android scenarios

What is Encapsulation?

Encapsulation is the bundling of data and methods that operate on that data into a single unit (class) and restricting direct access to some of an object's components.

Purpose:

• Protect internal object state
• Improve maintainability
• Secure sensitive logic

What is Inheritance?

Inheritance allows one class (child) to acquire properties and methods of another class (parent).

Types of Inheritance:

What is Polymorphism?

Polymorphism allows a single interface or method to behave differently depending on context.

Types of Polymorphism:

What is Abstraction?

Abstraction means showing only essential features while hiding implementation details.

Ways to Achieve:

Android Use Case:

• Interfaces for navigation callbacks
• Abstract BaseViewModel or Repository in MVVM

Abstract Class vs Interface

Real-World Android Use Cases

Conclusion

OOP is not just a theory—it's the foundation of robust Android development. Whether you write in Java or Kotlin, applying OOP principles will help you build clean, modular, and scalable apps.