Object Oriented Programming (OOP) concepts are the fundamental pillars of programming. The major objective of object-oriented approach is to eliminate some of the flaws encountered in the procedural approach. Object-Oriented Programming (OOP) is a software development paradigm that uses a set of fundamental concepts to structure and design software.

It is a high-level programming language based on the object-oriented programming (OOP) model. In Object-oriented programming, everything is viewed in terms of classes and objects. Classes and objects are the two main aspects of object-oriented programming. A class is a template for objects, and an object is an instance of a class.

OOP is one of the widely used programming paradigms adopted by software developers. There are many concepts of OOPs such as inheritance, encapsulation, polymorphism, etc. OOP relies on the concept of classes and objects. In OOP, objects interact with each other; have their own methods, procedures and functions; are part of a class and may be reused in one or more program. 

Popular OOP languages include C++, Java, Python and SmallTalk.

Structure of Object-Oriented Programming:

The structure, or building blocks, of object-oriented programming include the following:

• A class is a blueprint or template for creating objects. It defines the attributes (data members) and methods (functions) that objects of that class will have. For example, a Car class can define attributes like color and speed, as well as methods like start() and stop(). Classes are user-defined data types that act as the blueprint for individual objects, attributes and methods.
• An Object is an instance of a class. It represents a real-world entity and contains data and behaviors defined by the class. In the context of our Car class, an object could be a specific car, like “Innova”. Objects are the basic runtime entities in an object oriented system. They may represent a person, a place, a bank account or any item that the program may handle.
• Methods are functions that are defined inside a class that describe the behaviors of an object. Each method contained in class definitions starts with a reference to an instance object. Additionally, the subroutines contained in an object are called instance methods. Programmers use methods for reusability or keeping functionality encapsulated inside one object at a time.
• Attributes are defined in the class template and represent the state of an object. Objects will have data stored in the attributes field. Class attributes belong to the class itself.

Principles of Object-Oriented Programming:

 

Object-Oriented Programming Principles mainly include the 4 pillars that together make the OOP a very powerful concept. These four key principles of Object-Oriented Programming are: Inheritance, Encapsulation, Abstraction and Polymorphism.  These four principles are the foundational concepts of OOP and guide the design and organization of object-oriented software. They help create modular, reusable, and maintainable code by emphasizing the organization of code into classes, the management of data and methods within those classes, and the ability to extend and customize behavior through inheritance and polymorphism.

Following are the brief explanation of four key principle of OOP:

Inheritance –

Inheritance is one of the most significant and often used principles in Object-Oriented Programming. It is a way of creating new classes from existing class. Inheritance is a mechanism that allows a class (the subclass or derived class) to inherit properties and behaviors from another class (the superclass or base class).

Super Class: A superclass (or a base class or a parent class) is a class whose characteristics are inherited.

Sub Class: A subclass (or a derived class, extended class, or child class) is a class that inherits from another class. The subclass can add its own fields and methods to the superclass’s fields and methods.

Inheritance provides code reusability and establishes an “is-a” relationship between classes. It encourages “reusability,” which indicates that if we want to create a new class but there is already one with some of the code we need, we can derive our new class from the existing similar block of code. The existing fields and functions are used in this way.

For instance, a Bicycle class can inherit from a more general Vehicle class.

Encapsulation –

The process of encapsulating data into a single unit is known as encapsulation.  Encapsulation is binding or wrapping up of data into a single unit. It is used to secure the data and hide the implementation details from users. It allows accessing a level without disclosing the complex details behind it by declaring the objects as private. 

Encapsulation is the concept of bundling data (attributes) and methods (functions) that operate on that data into a single unit called a class. It involves controlling the access to data by using access modifiers (e.g., public, private, protected) and promoting data hiding. The encapsulation functions similarly to a shield. It prohibits other portions of the code from accessing the data.

Technically, under encapsulation, a class’s variables or data are concealed from other classes and can only be accessible by any class member function in which they are specified. This concept is referred to as data hiding.

Encapsulation is implemented by declaring all variables in the class to be private. In the class, public methods are defined to set and retrieve variable values.

Abstraction –

Abstraction is a OOPs feature which is use to display only important information while hiding the implementation details from the user. Java uses the concepts of abstract classes and interfaces to achieve data abstraction.

Abstraction hides the irrelevant details and exposes only what’s necessary. It focuses on what an object does rather than how it does it, making the software more manageable and user-friendly. For example, a Phone class abstracts the complex internal workings of a phone to provide a simple interface for making calls, sending texts, etc.

Polymorphism–

Polymorphism is a way of using common operation in different ways for different data input. Polymorphism, as the name suggests, means many forms. Poly means many and morph means forms. It is the ability of an object to take on many forms. In simple terms, OOPs demonstrates how a single entity can have multiple forms. 

Polymorphism has the following advantages:

Method Overriding

Overriding is a feature that allows a subclass or child class to implement a method that is already offered by one of its super classes or parent classes. When a subclass’s method has the same name, parameters or signature and return type (or sub-type) as a method in its super class, the subclass’s method is said to override the super-method class.

Method Overloading

When there are numerous functions with the same name but different parameters, it is referred to as overloading. Changes in the number of arguments or the kind of arguments can cause functions to become overloaded.

Benefits (Advantages) of OOP

Object-Oriented Programming (OOP) offers several advantages that make it a popular choice for software development.  It provides a clear modular structure for programs that enhances code re-usability. It provides a simple way to solve complex problems. It helps define more abstract data types to model real-world scenarios. It hides implementation details, leaving a clearly defined interface. It combines data and operations.

Here are some of the key benefits of OOP:

Modularity:  OOP promotes the organization of code into small, reusable modules (classes). Each class represents a distinct component or entity, making it easier to manage, maintain and understand complex software systems.

Reusability: OOP encourages code reusability. Once we create a class, we can reuse it in different parts of our application or in other projects. This reduces duplication of code and development time.  Code can be reused through inheritance, meaning a team does not have to write the same code multiple times.

Flexibility: OOP allows for easy modification and extension of software. You can create new classes (subclasses) that inherit the attributes and behaviors of existing classes (superclasses) and then customize or extend them to meet specific requirements.

Productivity:  Programmers can construct new programs quicker through the use of multiple libraries and reusable code.

Security: OOP principles like encapsulation and data hiding help improve software security by limiting direct access to data and promoting controlled interactions with objects.

Readability and Maintainability: OOP code is often more readable and easier to maintain because it reflects the real-world entities and their interactions, making it more intuitive for developers and future maintainers.

Scalability: OOP is well-suited for large, complex systems. It enables you to break down the problem into smaller, manageable components that can be developed and tested independently, facilitating the development of large-scale applications.

Encapsulation: Encapsulation hides the internal details of a class and provides a well-defined interface for interacting with objects. This reduces the risk of unintentional data corruption and helps maintain data integrity.

Abstraction: Abstraction simplifies complex systems by modeling entities at a high level of detail. It focuses on what an object does rather than how it does it, which enhances the manageability and understandability of the code.

Polymorphism: Polymorphism allows you to treat objects of different classes through a common interface, making your code more flexible and adaptable to changes. This promotes code extensibility and maintainability.

Applications of Object Oriented Programming:

Object-Oriented Programming (OOP) has found wide application in various domains due to its ability to model complex systems, promote code reuse, and enhance software maintainability. OOP’s versatility makes it suitable for a wide range of software development tasks, from large-scale applications to small, specialized projects in various industries. It encourages the creation of organized, modular, and maintainable code.

Some common applications of OOP include:

Software Development: OOP is widely used in general-purpose software development. Many programming languages such as Java, C++, C#, and Python are designed with OOP in mind. OOP allows for structuring software into classes and objects, making it easier to manage and extend.

User Interface Design: Graphical user interface (GUI) applications benefit from OOP by allowing developers to create user interface elements (buttons, windows, dialogs) as objects with associated behaviors. This makes GUI development more intuitive and modular.

Game Development: OOP is extensively used in game development. Game objects like characters, enemies, and items can be modeled as classes, each with their unique properties and behaviors. Inheritance and polymorphism are crucial for building complex game structures.

Simulation Software: In fields like physics, engineering, and healthcare, OOP is used to model and simulate real-world systems. Objects represent entities or components within the system, and their interactions are defined through classes and methods.

Database Systems: Object-Relational Mapping (ORM) libraries, like Hibernate in Java and Entity Framework in C#, use OOP to map database tables to objects. This simplifies database operations by allowing developers to interact with the data using objects and their methods.

Web Development: Frameworks like Ruby on Rails, Django (Python), and ASP.NET (C#) use OOP principles to organize web applications. Each part of a web application, such as models, controllers, and views, can be represented as objects, making the code more maintainable.

Embedded Systems: OOP is used in embedded software development where it helps structure and modularize code for devices like microcontrollers, sensors, and IoT devices. It can make it easier to manage complex, resource-constrained systems.

Artificial Intelligence and Machine Learning: OOP is applied in AI and machine learning projects. Classes and objects can be used to model various AI components such as neural networks, decision trees, or reinforcement learning agents.

Financial Applications: In finance, OOP is used to represent financial instruments, accounts, and transactions. It simplifies the modeling of complex financial structures, risk analysis and portfolio management.

CAD and 3D Modeling Software: Computer-Aided Design (CAD) software and 3D modeling tools use OOP to represent geometric shapes, transformations, and modeling entities. OOP simplifies the manipulation of complex 3D scenes.

Operating Systems: Some parts of modern operating systems are designed using OOP principles. For example, objects represent processes, files, and hardware components and their interactions are defined through classes and methods.

Education and Training: OOP is widely taught in computer science and software engineering education. It provides a foundation for understanding software design and programming concepts.