OOPs Concepts in Java: An Introduction

If you're curious about programming languages, you've probably heard about Object-Oriented Programming System (OOPs) concepts in Java. OOPs is a popular programming method that emphasises the use of objects and classes to represent real-world entities and concepts in code. Java, one of the most pursued programming languages in the world, fully supports OOPs concepts. Its many features, such as OOPs Concepts in Java make it an ideal language for building complex and scalable applications.   

According to the TIOBE Programming Community Index, Java ranked fourth among the most popular programming languages in 2024. This is due to the extensive use of Java in the development of enterprise-level applications, mobile applications, and web applications.  

Java's platform independence, object-oriented architecture, and extensive use in various applications make it a valuable language to learn. This blog covers OOPs Concepts in Java with examples, including its working and concepts. Read further to learn more about Object-Oriented Programming System. 

Table of Contents

1) What is Object Oriented Programming (OOPs)? 

2) What are OOPs in Java? 

3) List of OOPs Concepts in Java 

4) The working of OOP Concepts in Java 

5) Differences between OOP and other programming styles 

6) Conclusion 

What is Object Oriented Programming System (OOPs)? 

An Object-Oriented Programming System (OOPs) is a programming model that focuses on creating objects that contain data and methods to operate on that data. In simpler terms, it makes it easier to organise and manage complex programs. OOPs helps break the program into smaller and self-contained objects that can be reused differently. It also makes programs more flexible and adaptable to changes because you can modify the behaviour of an object without affecting other objects in the program. 
 

What are OOPs in Java? 

Java’s Object-Oriented programming System concepts are based on four essential ideas: abstraction, encapsulation, inheritance, and polymorphism. Essentially, OOPs in Java allows developers to create building blocks called methods and variables that can be used repeatedly in different programs. It helps to keep critical data and code hidden from outside sources. Additionally, it makes programming easy and saves time. Understanding OOPs concepts is essential for comprehending how Java operates.  

Java outlines its OOPs concepts in the following ways: 

Abstraction: In Java, abstraction is a way to hide complex details and display only the essential features of any object to the user. It is like a television's remote control in that you do not need to know how it works; you just need to know which button is used to change channels, adjust the volume, or turn it on or off. It helps in creating code that is reusable and easier to maintain. 

Encapsulation: It is the act of keeping fields within a class private and allowing access to these fields through public methods. Encapsulation works like a treasure box that keeps valuable things inside it. In Java, you can hide some parts of the code and only reveal what is necessary for the other parts of the program to use. This helps in protecting the code from external interference and makes it easier to maintain and update in the longer run. 

Inheritance: Inheritance is a unique aspect of Java that enables programmers to create new classes that share some characteristics of existing classes. It is like passing down certain traits from one generation to the next. Inheritance involves creating a new class based on an existing one but with some modifications. The new class is called a subclass, while the original class is called the superclass. 
 

Polymorphism: Polymorphism in Java allows programmers to use the same term to represent different meanings in different contexts, like changing appearance based on the situation. This feature enables you to write more reusable and flexible code.  

There are two forms of polymorphism: Method Overloading (compile-time polymorphism) is the first, where the code implies a different meaning based on the number, type, or order of arguments passed to a method. Second is Method Overriding (run-time polymorphism), where a subclass provides a specific implementation of a method already defined in its superclass, and the behaviour is determined at run-time based on the object type. 

Learn how to develop web applications using Java programming with our Web Development Using Java Training course now! 

List of OOPs Concepts in Java 

Following is the list of Java OOPs concept: 
 

The working of OOPs Concepts in Java 

Java's OOPs concept allows programmers to design reusable components that ensure security across various use cases. Read further to understand the workings in more detail: 

How does abstraction work? 

Abstraction is a concept in Java that creates complex programs by breaking them down into simpler components. As discussed above, it is a way of hiding the details of components and displaying only the relevant details to the user. It can be achieved in two ways: via abstract classes and by using interfaces. An abstract class is used for partial to complete abstraction, while an interface is used for complete abstraction.  

An abstract class is a class that cannot be instantiated on its own but serves as a pattern for other classes to inherit from. It defines some methods and properties that the subclasses must take, but it may also have abstract methods that are left undefined. The undefined functionality can be used for redefining and making changes for further purposes. 

An interface defines a collection of abstract methods and a proper blueprint for a class to follow. Any class that implements an interface must implement all the methods defined in the blueprint. This allows for a common set of traits across all the classes without requiring them to have a common superclass. 

How does encapsulation work? 

Encapsulation helps to keep code organised by securing certain parts of an object or class in Java. It is achieved using access modifiers such as public, private, and protected. These access locks determine which parts of an object or class should be visible or accessed and which should not. 

To understand this with an example, let's consider a class called "Person" with three properties: "name", "address", and "contact". You want to make sure that the "name" and "address" can be accessed and modified by other parts of the program, but you want to keep the "contact" property private because it contains sensitive data. Encapsulation can be used to ensure that it cannot be accessed or modified by anything outside of the "Person" class. 

How does inheritance work? 

Java's OOP concept of inheritance allows you to create new classes based on existing classes by inheriting their behaviours and properties. The inheriting class is referred to as a subclass or child class, while the original class is commonly referred to as the parent or superclass. 

For instance, let's imagine you have a class called "Animal" that has properties like "name", "age", and "breed", and behaviours like "sleep()" and "eat()". Now you want to create a new class called "Dog" that is similar to "Animal" but has some more properties and behaviours that are specific to dogs, like "bark()" and "run()". 

You can use inheritance to create the "Dog" class based on the "Animal" class instead of creating a new class from scratch. This means that the "Dog" class will automatically have all the properties and behaviours of the "Animal" class, and you can add new ones specific to dogs. 

How does polymorphism work? 

In Java, polymorphism involves referencing a parent class to manipulate an object in the child class. It allows objects of different types to be treated as if they are the same type, making code more reusable and flexible.  

For example, let's consider a class hierarchy for different types of vehicles. The base class is called "Vehicle" and has a method called "move". The subclasses "Car" and "Bike" inherit from "Vehicle" and implement the "move" method in their own way.  

Using polymorphism, you can create an array of "Vehicle" objects and populate it with "Car" and "Bike" objects. Then, you can call the "move" method on each object in the array using a loop, even though the objects are of different types. This is because each object in the array is treated as a "Vehicle" object, which has a "move" method.  

This allows you to write more flexible codes that can work with different types of objects without knowing the exact type of each object. 

Differences between OOPs and other programming styles

OOPs have gained widespread popularity due to their numerous advantages over alternative programming paradigms like Procedural and Functional Programming.

Procedural Programming is centred on a series of procedures or functions, each representing a sequence of instructions for a specific task. It emphasises a step-by-step approach to task completion. In contrast, OOPs revolve around objects and their interactions as a solution to problems.

Functional Programming, conversely, emphasises using functions that generate output based on input without altering external states. It relies on mathematical functions and is characterised by immutability and statelessness. In contrast, OOPs are grounded in objects and their states, making them suitable for managing complex, stateful systems.

Crack your Interview with Java Questions and Answers Guide. 

Advantages of OOPs Concepts

Some notable benefits of OOPs Concepts are as follows:

Re-usability: Achieved through class usage for writing once and deploying multiple times.

Data redundancy: Minimised by addressing the storage of the same data in different locations. Also utilises inheritance for common functionalities among multiple classes.

Code maintenance: Simplifies modification and maintenance of existing code and allows for easy creation of new objects with minor differences.

Security: Ensures data hiding and abstraction for limited exposure and enhances security by providing only necessary data visibility.

Design benefits: Facilitates extensive design phases for better designs and eases non-OOP programming at critical program limits.

Easy troubleshooting: Encapsulation ensures self-constrained objects for easy problem resolution while eliminating code duplicity.

Flexibility: Supports problem-solving by offering flexibility in design and implementation.

Conclusion 

OOPs concepts in Java are fundamental to organising code in a more structured and manageable manner. By using OOPs concepts like encapsulation, inheritance, and polymorphism, programmers can develop robust and reusable code that is easy to maintain and extend. Understanding these concepts is essential for any Java developer who wants to write efficient and scalable code. With practice and experience, you can become proficient in OOPs and develop applications that meet the industry's ever-increasing demands. 

Know how to develop an application using Java with our Java Swing Development Training course today!