4 Pillars of Object Oriented Programming

Discover the fundamental principles of 4 Pillars of Object Oriented Programming (OOP) with this comprehensive guide. Learn about the 4 pillars: Encapsulation, Inheritance, Polymorphism, and Abstraction. Gain a deeper understanding of OOP concepts and how they empower software development!

Introduction to Object Oriented Programming Languages

The object-oriented programming (OOP) language style emphasizes the use of objects in the construction of programs. Its foundation is the idea that all data and the procedures required to alter it are contained within objects. This means that the data and operations are kept together, making it easier to maintain the program.

OOP is different from traditional programming, which is based on functions and procedures. Traditional programming focuses on the code while OOP focuses on the objects that the code manipulates. OOP is based on the idea of objects, which are self-contained pieces of data and code.

Each object has unique properties and operations. The size, color, or name of the object are only a few examples of an attribute. The object’s methods perform operations on it, such as changing its color, determining its size, or displaying its name. More complex objects can be made by combining simpler objects.

The foundation of OOP is the concept of inheritance, which refers to an object’s capacity to take on the attributes and operations of other objects. This makes it possible to create objects that are interconnected and have similar characteristics and functions. This makes it simpler to develop programs that are also simpler to reuse and maintain.

Code reuse, or the capacity to use the same code repeatedly without having to rewrite it, is another benefit of OOP. The amount of work required to develop a program is reduced as a result.

Concrete examples of OOP:

  1. A car object can have attributes such as color, make, and model, and methods such as accelerate, brake, and turn.
  2. A customer object can have attributes such as name, address, and phone number, and methods such as placeOrder and checkBalance.
  3. A calculator object can have attributes such as total, current number, and operation, and methods such as add, subtract, multiply, and divide.
  4. A shopping cart object can have attributes such as items and total cost, and methods such as addItem and removeItem.
  5. An employee object can have attributes such as name, job title, and salary, and methods such as getBonus and getRaise.

4 Pillars of Object Oriented Programming

In the object-oriented programming (OOP) paradigm, objects and their interactions are used to design and create applications. OOP focuses on the creation of objects that contain data and methods that can act on that data. Encapsulation, abstraction, inheritance, and polymorphism are the four main OOP ideas.

Encapsulation is the process of fusing information and operations into one thing, or object. Then, this object can be used to store and modify data, as well as to call the corresponding methods. Encapsulation helps to keep the data and methods safe from outside interference and misuse.

The technique of disguising an object’s implementation specifics is called abstraction.
It makes it possible to utilize the object without the user being aware of its implementation. This can help to reduce complexity and improve maintainability. Abstraction also helps to make code more modular, allowing for easier reuse and modification.

The technique of constructing new classes from older classes is known as inheritance.
The superclass, an existing class, and its characteristics and functions are passed down to the new classes, often known as subclasses. This allows for the creation of hierarchical relationships between classes.

The capacity of an object to assume various forms is known as polymorphism.
It enables the interchangeability of objects from various classes within a program.
For example, if two objects of different classes use the same method, the result depends on which object was used.

Encapsulation, abstraction, inheritance, and polymorphism are the four main OOP ideas. These ideas aid in improving the organization, maintainability, and reusability of code. They also help to reduce complexity and make applications easier to understand and modify.


  1. Encapsulation: A user class with methods for accessing and modifying user data and storing user information (name, email, etc.).
  2. Abstraction: Database class that interacts with a database without requiring the user to be familiar with the specifics of how the database operates is called an abstraction.
  3. Inheritance: Subclasses of the user class that add new information and methods to the user class through inheritance.
  4. Polymorphism: Two different classes that both have a method to calculate the area of a circle, but the results will be different depending on the class used.

Object & Classes

Objects are used to represent and manipulate data in object-oriented programming (OOP), a language approach. Programmers can write programs that are simpler to construct, maintain, and comprehend thanks to the effective OOP programming technique. Classes and objects are the two key concepts in OOP.

A class is the blueprint from which objects are created. It defines the behavior and characteristics of an object.

It serves as a blueprint for building objects and specifies the properties and methods that each one will have. An object is a physical thing with behavior and data attached to it. It is produced by utilizing the class as a template and is an instance of a class. Classes and objects can be used to model real-world concepts.

For instance, objects that represent cars can be made using the car class. The car class could define attributes such as color, engine size, and model, and it could define methods such as drive and park.

Then, using the car class, objects representing various cars, such as a red Ford Focus or a blue Toyota Corolla, can be made. In OOP, classes and objects are used to create complex and powerful programs.

The program is written by defining the behavior of each object, and the objects interact with one another to carry out tasks. OOP offers a potent method for making systems that are simpler to develop, maintain, and comprehend.

Concrete Examples:

Class: Car
Attributes: color, engine size, model
Methods: drive, park
Object: Red Ford Focus
Attributes: color (red), engine size (2.0L), model (Ford Focus)
Methods: drive, park
Object: Blue Toyota Corolla
Attributes: color (blue), engine size (1.8L), model (Toyota Corolla)
Methods: drive, park


The programming approach known as object-oriented programming (OOP) is built on the concept of objects. These objects contain both data and functions that can be used to manipulate the data. An object’s methods are a particular kind of function created specifically to interact with the data contained therein.

In other words, they are a collection of instructions that operate on the object’s data. The key distinction between methods and standard functions is that methods are tied to a particular object. This implies that when calling a method, you must specify the object on which it is to be called.

Additionally, methods can access and manipulate the data of the object they belong to, while regular functions cannot. Methods are used to achieve various tasks within an object.

For instance, a method could be used to alter the object’s data in some way or to generate a result from the object’s data. Since one object can call a different object’s method, methods serve as an essential means of inter-object communication.
As a result, it is simpler to maintain the organization of the code because all related functions may be gathered into a single object.

Concrete Examples:

  1. A Point class in a drawing program may have methods to move the point around the canvas, change its color, or draw it on the canvas.
  2. A ShoppingCart class might provide methods for adding goods to the cart, taking items out of the cart, or figuring out how much everything in the cart would cost in total.
  3. A Student class may have methods to add a student to a class roster, drop a student from a class, or calculate a student’s grade.


Inheritance is a key concept in object-oriented programming (OOP). It speaks of an object’s capacity to take on the traits of other objects. In other words, it makes it possible for traits and behaviors to be passed down from one class of objects to another. This is a powerful concept that helps reduce code complexity and promote code reuse.

A class connection where one class is the parent or superclass and the other is the child or subclass is known as inheritance. The subclass can both introduce new properties and methods while also inheriting all of the parent class’s existing ones. This enables developers to design a hierarchy of classes in which a subclass can make use of both its parent class’s and own properties and functions.

Inheritance is a very useful technique for OOP development because it lets programmers add new classes on top of old ones. As a result, less new code needs to be written and older code is easier to maintain and update.

Additionally, it enables programmers to design intricate programs with a clear and organized codebase. Any OOP developer who wants to write effective and efficient code must comprehend and master the idea of inheritance.

Concrete examples of inheritance in OOP:

  1. A subclass of the class Animal inheriting the properties and methods of the parent class, such as the ability to move, eat, and reproduce.
  2. A class’s subdivision Having the ability to move, accelerate, and change direction as well as inheriting the parent class’s properties and methods.
  3. A class’s subdivision Person who has the ability to speak, think, and feel, as well as the parent class’s properties and methods.
  4. A class’s subdivision inheriting the parent class’s methods and properties, including the capacity to work, be paid, and receive benefits.