The 4 Pillars of OOP (Object Oriented Programming)

Q: What are the 4 concepts of OOP?

The 4 pillars of OOP with example are: Encapsulation restricts direct access to data, such as a BankAccount class with private balance and public deposit(). A Car class uses abstraction through a drive() method that conceals its implementation details from users. Through inheritance, a class obtains properties and attributes from another class, such as a Dog receiving characteristics from an Animal. The same method, called draw() behaves differently based on the implementing class selection in Circle and Square classes through polymorphism.

Updated on March 19, 2025

Article Outline

What is OOP?Decoding OOP: Understanding Its Four Foundational Pillars Using the 4 Pillars of OOP in Real Projects Benefits of the 4 Pillars of OOP Basic Design Principles of OOP Conclusion FAQs

Object-oriented programming Systems (OOPs) are very easy to design and develop. The concept around which it builds is around ‘objects’, classes with encapsulated data and behavior. By improving modularity, code reusability, and maintainability, OOP is what makes it the choice of software development today.

The OOP is based on four fundamental principles namely, abstraction, encapsulation, inheritance, and polymorphism. The 4 Pillars of OOP are often referred to as the foundation for building an efficient and scalable application. This article will explore these concepts in detail with examples of how they can be applied in practice.

What is OOP?

Programmers use Object-oriented programming (OOP), a design method that creates programs by linking data values to specific behaviors through objects. In contrast to procedural programming logic, OOP applies classes to store reusable code that specifies both object properties and behaviors. This strategy makes programs quicker to develop and extend and easier to sustain.

The programming languages Java, C++, Python, and C# use OOP to develop applications starting from basic scripts up to sophisticated systems. Thanks to its fundamental role in modern programming practice, a programmer can utilize OOP as a structured method to work with real-world entities through code.

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Decoding OOP: Understanding Its Four Foundational Pillars

1. Abstraction

Abstraction makes complex systems easy to manage because it concentrates on important information and hides unnecessary data. It allows developers to interact with objects without knowing what is happening inside.

Abstraction Using Classes

OOP defines classes as templates whose instances are objects. They encapsulate attributes and behaviors relative to a specific entity and help programmers work at a higher level of abstraction.

Abstraction Using Header Files

In languages such as C++, header files also separate interface declarations from implementation. This permits developers to use functions and classes without knowing how they are built.

Example

Consider an abstract class in Python:

from abc import ABC, abstractmethod

class Vehicle(ABC):

@abstractmethod

def start_engine(self):

pass

class Car(Vehicle):

def start_engine(self):

return "Car engine started"

car = Car()

print(car.start_engine())

Output:

Car engine started

In this example, Vehicle is an abstract class with an abstract method start_engine(), which is later implemented by Car. The user only needs to call start_engine() without knowing the internal mechanics.

2. Encapsulation

The encapsulation concept bundles data with operating methods into individual units to protect data from unauthorized modifications.

Example:

public class BankAccount {

private double balance;

public BankAccount(double initialBalance) {

balance = initialBalance;

}

public void deposit(double amount) {

balance += amount;

}

public void withdraw(double amount) {

if (amount <= balance) {

balance -= amount;

} else {

System.out.println("Insufficient funds");

}

}

public double getBalance() {

return balance;

}

}

Here, the balance attribute is private, ensuring that external classes cannot access or modify it directly. Instead, methods like deposit() and withdraw() control modifications, preserving the integrity of the object’s state.

3. Inheritance

The inheritance programming technique enables classes to inherit their properties and behaviors from existing classes, establishing reusable code structures in code development.

Example

#include <iostream>

using namespace std;

class Animal {

public:

void makeSound() {

cout << "Animal makes a sound" << endl;

}

};

class Dog : public Animal {

public:

void makeSound() {  // Overrides Animal's method

cout << "Dog barks" << endl;

}

};

int main() {

Dog dog;

dog.makeSound();

return 0;

}

Output:

Dog barks

Here, Dog inherits from Animal and overrides the makeSound() method to provide its specific behavior while retaining the properties of the parent class.

4. Polymorphism

The same method will exhibit different behaviors depending on the object instance, which triggers its execution, which improves programming versatility.

Operator Overloading

In C++:

class Complex {

public:

int real, imag;

Complex(int r, int i) : real(r), imag(i) {}

Complex operator + (const Complex& obj) {

return Complex(real + obj.real, imag + obj.imag);

}

};

This program demonstrates polymorphism through the + operator function definition that handles Complex numbers.

Function Overloading

The same name can represent different functions through function overloading when parameters differ.


class MathOperations {

public:

int add(int a, int b) {

return a + b;

}

double add(double a, double b) {

return a + b;

}

};

The add() method is defined twice, handling both integer and double addition differently.

Using the 4 Pillars of OOP in Real Projects

Implementing OOP principles generates code which enables scalability and maintainability during projects. For example:

The method interface provided by abstraction enables API design because users can call methods regardless of their implementation specifics.
The banking industry depends on encapsulation to prevent unauthorized access to privileged data.
Frameworks that use inheritance derive base functionality from generic classes.
Through polymorphism, programmers can achieve flexibility because methods are executed dynamically.

Benefits of the 4 Pillars of OOP

Adopting principles from object-oriented programming systems delivers major conceptual advantages to software creation, leading to higher maintenance levels, stronger protection, and performance improvements. The 4 pillars of OOP are Inheritance, Encapsulation, Polymorphism, and Abstraction, which maintain the system effectiveness of an OOP-based development.

1. Code Reusability (Inheritance)

Through inheritance, programmers can derive reusable properties from existing classes. Because the base class contains shared functionalities, developers must write code only once rather than repeating it across multiple components. This approach reduces development time and ensures consistency across multiple components.

2. Security and Data Protection (Encapsulation)

Encapsulation protects data by blocking unauthorized access to a class’s attributes and methods. OOP maintains information security through its privately protected and publicly accessible definitions, allowing accessible data entry only through the defined getter and setter interfaces. This approach achieves better data integrity, preventing modifications when set improperly.

3. Flexibility and Scalability (Polymorphism)

Polymorphism enables a single interface to handle different types of behaviors dynamically. It allows methods to be overridden in subclasses or multiple methods with the same name to perform varied operations based on input parameters. This flexibility supports code scalability, making extending functionality without modifying existing code easier.

4. Modular Code and Maintainability (Abstraction)

The abstraction method presents vital system information through abstract representations that hide implementation elements. High-level interaction enables developers to craft easily maintainable and modifiable code during development, simplifying programming comprehension and testing tasks. Teams working on different modules cooperate efficiently because they do not need to understand every implementation detail.

Basic Design Principles of OOP

Object-oriented programming establishes various design principles that produce efficient, adaptable software that is easy to understand and maintain. These principles enable developers to create better code by preventing mistakes and ensuring that updates run smoothly while maintaining code quality.

1. Learning SOLID: Set of 5 Rules to Improve OOP Code Quality

The SOLID principles are five important rules that help write better object-oriented code.

Single Responsibility Principle (SRP): A class should have only one job. If it is responsible for multiple things, changes in one area might affect the others.
Open/Closed Principle (OCP): The code system needs to be extended while remaining resistant to modificatiInstead of adjusting existing code, new. New classes are the proper method for adding new fea code.
Liskov Substitution Principle (LSP): A child class should be able to replace its parent class without breaking the program.
Interface Segregation Principle (ISP): A class should only have the necessary methods. Instead of having a large interface with many functions, break it into smaller ones.
Dependency Inversion Principle (DIP): A class should depend on abstractions/interfaces rather than concrete implementations.

2. DRY (Don’t Repeat Yourself): Reduce Repetition

The DRY principle means avoiding duplicate code using functions, classes, or modules.

Example: Instead of writing separate login validation for mobile and email, create a Validator class that handles both.

Such an approach decreases physical and logical errors, simplifies maintenance tasks, saves time due to one-location changes, and improves code readability.

3. KISS (Keep It Simple, Stupid): Make Code Easy to Understand

According to the KISS principle, the code should be kept simple. Complex programming code increases the difficulty of debugging operations and requires extra maintenance efforts.

How to Keep Code Simple?

Select descriptive names for functions alongside variables.
Complex loops and conditions should be placed at a shallow level throughout the code.
Each function should only perform one distinct task.

Example: Functions containing many responsibilities should be divided into smaller functions that can be used repeatedly.

4. YAGNI (You Ain’t Gonna Need It): Avoid Unnecessary Features

The YAGNI principle states that you should not add features unless they are necessary.

Example: Don’t write a function for exporting data to XML if the project only requires JSON support.

5. Composition Over Inheritance: Prefer Composition for Flexibility

Instead of inheriting from a parent class, composition (combining objects) is often better.

Example: Instead of making a Car inherit from an Engine, give the Car an Engine object inside it.

6. Law of Demeter (LoD): Reduce Unnecessary Dependencies

The Law of Demeter states that an object should only interact with its direct dependencies.

Example: A Car with an Engine should not directly modify the Piston inside the Engine. Instead, it should call engine.start().

7. Tell, Don’t Ask: Let Objects Do Their Work

Instead of asking an object for data and making decisions outside of it, tell the object to do the work.

Example:

Instead of:

if (user.isActive()) {

user.sendNotification();

}

Use:

user.notifyIfActive();

8. Avoid Premature Optimization: Focus on Clarity First

Optimizing your code before writing a correct and clear implementation can be counterproductive. The initial step involves creating direct and error-free code before you can optimize when suitable.

Example: You should concentrate on writing clean code before you dedicate long hours to optimizing short-duration functions.

Conclusion

Four essential principles form the OOP development framework for making efficient programming systems. Abstraction, Encapsulation, Inheritance, and Polymorphism. Through its fundamental OOP principles, programmers obtain capabilities to develop software code that promotes organization alongside enhanced maintainability and scalability characteristics and elevated code reusability.

The ability to develop adaptable software emerges for developers who master the principles of Object-Oriented Programming. The fundamental OOP principles help developers with different experience levels to develop practical programming code efficiently. Enrol in the Certificate Program in Application Development powered by Herovired for more insights on application development and the concepts of OOPs.

FAQs

What are the 4 concepts of OOP?

The 4 pillars of OOP with example are:

Encapsulation restricts direct access to data, such as a BankAccount class with private balance and public deposit().
A Car class uses abstraction through a drive() method that conceals its implementation details from users.
Through inheritance, a class obtains properties and attributes from another class, such as a Dog receiving characteristics from an Animal.

The same method, called draw() behaves differently based on the implementing class selection in Circle and Square classes through polymorphism.

What are the 4 pillars of OOP and their relationship in practical programming?

Implementing Abstraction with Encapsulation, Inheritance, and Polymorphism allows programmers to create more organized and reusable code that scales better. The “4 pillars of OOPs concept” functions as a unified system, supplying Abstraction for simple logic, encapsulation to protect data, inheritance for code reuse, and Polymorphism for flexible code. Software development proves more effective because all four pillars function together as one system.

How does Encapsulation achieve its vital role in OOP?

Encapsulation data remains protected because developers only need to access data through method definitions. The barrier for access controls accidental changes while boosting security and facilitating code management.

Inheritance serves what purpose when coding?

Enabling inheritance allows a class to obtain properties and behaviors from another without duplicating code. This saves time, eliminates mistakes, and simplifies update processes.

Does a class can apply multiple OOP principles throughout its development?

Yes! A class uses encapsulation features to secure data while inheriting code through inheritance methods. Polymorphism alters functions, and abstraction conceals complexity. Modern real-world programs usually implement several combinative principles of OOP.

What benefits does polymorphism provide when developing programs?

The same function method operates differently based on which object it handles through polymorphism. Programmers benefit from code flexibility when using this approach, which decreases repeated sections while supporting code expansion and maintenance.

Updated on March 19, 2025

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