Abstraction in Java 🚀

By Bhau Automation • Java OOPs Concepts Tutorial

🎯 What You Will Learn

What is abstraction in Java?
What is abstract class?
What are abstract methods?
Difference between abstraction & encapsulation
When to use abstract class and interface
Java interview questions on abstraction

💡 Abstraction is one of the core OOPs concepts in Java and is widely used in enterprise applications and interviews.

📌 What is Abstraction in Java?

Abstraction means hiding implementation details and showing only essential functionality to the user.

In Java, abstraction helps developers:

Reduce code complexity
Improve security
Increase code maintainability
Achieve loose coupling

⚙️ What is an Abstract Class?

An abstract class is a class declared using the abstract keyword. It cannot be instantiated directly.

abstract class Animal {

}

🛠️ What is an Abstract Method?

An abstract method is a method without implementation (without body).

abstract void sound();

Child classes must provide implementation for abstract methods.

💻 Abstract Class Example in Java

abstract class Vehicle {

    abstract void start();

    void fuel() {

        System.out.println("Vehicle needs fuel");
    }
}

class Car extends Vehicle {

    void start() {

        System.out.println("Car starts with key");
    }
}

public class AbstractDemo {

    public static void main(String[] args) {

        Car c = new Car();

        c.start();

        c.fuel();
    }
}

📚 Abstract Class vs Interface

Feature	Abstract Class	Interface
Methods	Abstract + Concrete	Mostly Abstract
Variables	Can have instance variables	Only constants
Inheritance	Single	Multiple

🔒 Abstraction vs Encapsulation

Abstraction	Encapsulation
Hides implementation	Hides data
Achieved using abstract class/interface	Achieved using private variables
Focuses on what object does	Focuses on data protection

🔥 When to Use Abstract Class?

When classes share common behavior
When partial implementation is needed
When common methods are required
When maintaining code reusability

🌍 Real-World Use Cases

Banking systems
Payment gateways
Automation testing frameworks
Spring Boot applications

❓ Common Interview Questions

Q: Can we create object of abstract class?

A: No, abstract classes cannot be instantiated.

Q: Why do we use abstraction?

A: To hide implementation details and reduce complexity.

Q: Can abstract class have constructor?

A: Yes, abstract classes can have constructors.

🎥 Watch Complete Video Tutorial

👉 Watch Abstraction in Java Tutorial

🎓 Key Takeaways

Abstraction hides implementation details
Abstract classes cannot be instantiated
Abstract methods do not contain body
Abstraction improves maintainability
Important Java OOPs interview topic

⚡ Pro Tip: Practice abstract class and interface programs regularly to master Java OOPs concepts deeply.

🚀 Created with ❤️ by Bhau Automation

Abstraction in Java – Abstract Class, Abstract Methods & Encapsulation Explained