Abstract Class in Java 🚀

By Bhau Automation • Java OOPs Concepts Tutorial

🎯 What You Will Learn

What is an abstract class in Java?
How abstract classes work
Difference between abstract and concrete methods
Real Java code examples
Java interview questions and answers

💡 Abstract classes are one of the most important concepts in Java OOPs and are widely asked in interviews.

📌 What is an Abstract Class?

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

Abstract classes are mainly used to:

Provide abstraction
Achieve code reusability
Define common behavior
Create partially implemented classes

⚙️ Abstract Method vs Concrete Method

Method Type	Description
Abstract Method	Method without body
Concrete Method	Method with complete implementation

🛠️ Syntax of Abstract Class

abstract class Animal {

    abstract void sound();

    void sleep() {
        System.out.println("Animal is sleeping");
    }
}

💻 Java Abstract Class Example

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();
    }
}

🔥 Rules of Abstract Class

Abstract class cannot be instantiated
Abstract class may contain abstract and non-abstract methods
Child class must implement abstract methods
Abstract methods do not have method body

📊 Difference Between Abstract Class & Interface

Feature	Abstract Class	Interface
Methods	Abstract + Concrete	Mostly Abstract
Keyword	abstract	interface
Inheritance	Single	Multiple

🌍 Real-World Use Cases

Banking applications
Payment gateway systems
Game development
Automation testing frameworks

❓ Common Interview Questions

Q: Can we create object of abstract class?

A: No, abstract classes cannot be instantiated.

Q: Can abstract class have constructor?

A: Yes, abstract classes can have constructors.

🎥 Watch Complete Video Tutorial

👉 Watch Abstract Class in Java Tutorial

🎓 Key Takeaways

Abstract class provides abstraction in Java
Abstract methods do not contain body
Child classes implement abstract methods
Important Java OOPs interview topic
Widely used in real-world Java applications

⚡ Pro Tip: Practice abstract class programs regularly to understand abstraction deeply for interviews and Java projects.

🚀 Created with ❤️ by Bhau Automation

Abstract Class in Java – How It Works with Examples & Interview Questions