OOP.Inheritance

👨‍👦 What is Inheritance?

Inheritance is the mechanism in Object-Oriented Programming where one class (child/subclass) derives (or inherits) properties and behavior (methods) from another class (parent/superclass).

It’s like saying:

“A child class gets all the traits of its parent class.”

This promotes code reuse because you don’t need to rewrite common functionality — you define it once in the parent, and all children automatically get it.

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🔗 Inheritance Example

Parent class (superclass)

class Animal {
    void eat() {
        System.out.println("This animal eats food.");
    }
}

Child class (subclass)

class Dog extends Animal {  // 'extends' means Dog inherits from Animal
    void bark() {
        System.out.println("Woof Woof");
    }
}

Using Inheritance

public class Main {
    public static void main(String[] args) {
        Dog dog = new Dog();
        dog.eat();  // inherited from Animal
        dog.bark(); // defined in Dog
    }
}

✅ Dog can eat() even though eat() was never written in Dog — it inherited it from Animal.

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💡 Types of Inheritance (in Java)

Type	Example
Single Inheritance	One class inherits from one class (like Dog inherits Animal).
Multilevel Inheritance	Class A → Class B → Class C (a chain).
Hierarchical Inheritance	One parent class, multiple child classes.
Multiple Inheritance (via Interfaces)	Java doesn’t support multiple inheritance with classes (to avoid conflicts), but it supports it with interfaces.

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🚀 Benefits of Inheritance

✅ Reuse code instead of duplicating it.
✅ Follow the “is-a” relationship — a Dog is an Animal, a Car is a Vehicle.
✅ Makes the code easier to maintain and extend.

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⚠️ Inheritance Gotchas

• If not used carefully, it can lead to tight coupling (child depends too much on parent).
• Favor Composition over Inheritance if a class doesn’t truly follow “is-a” logic.