Inheritance in Java

What is Inheritance?

Inheritance in Java is a feature where one class (child) can use the properties and methods of another class (parent).

• The class that is inherited from is called Parent / Superclass
• The class that inherits is called Child / Subclass
• Java uses the keyword extends to achieve inheritance.

In short

• Parent class → Superclass
• Child class → Subclass
• Keyword used → extends

🧠 Real-World Idea

Think like this

• A Car is a Vehicle
• A Dog is an Animal
• A Student is a Person

This “IS-A” relationship is exactly what inheritance represents.

💻 Simple Code Example

class Vehicle {
    void start() {
        System.out.println("Vehicle is starting");
    }
}

class Car extends Vehicle {
    void drive() {
        System.out.println("Car is driving");
    }

    public static void main(String[] args) {
        Car c = new Car();
        c.start();   // inherited
        c.drive();   // own method
    }
}

📌 Why Do We Need Inheritance?

• Code reusability
• Reduces duplicate code
• Improves maintainability
• Supports method overriding
• Helps achieve runtime polymorphism

📌 Types of Inheritance

1️⃣ Single Inheritance

One child → One parent

class A {}
class B extends A {}

✅ Advantages of Inheritance

• Code reusability
• Less duplication
• Easy maintenance
• Supports polymorphism
• Clean structure

❌ Disadvantages of Inheritance

• Tight coupling
• Parent changes affect child
• Complex hierarchy
• Not always flexible