Inheritance

Analogy: biology

Inheritance is like DNA. You inherit features (eyes, hair color) from your parents, but you also add your own unique traits.

In code, a Child Class gets all the code from a Parent Class for free!

The Robot Factory

Why build a robot from scratch every time?

Start with a Basic Robot (Head, Body, Legs).
Create a Warrior Robot that extends Basic Robot and adds a Weapon.
Create a Flying Robot that extends Basic Robot and adds Wings.

Robot Builder (Inheritance)

Select Class

Inheritance Logic:

The Parent Class. Has basic movement and sensors.

The Code

Java Example

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// The Parent Class
class BasicRobot {
    void walk() {
        System.out.println("Walking...");
    }
}

// The Child Class
class WarriorRobot extends BasicRobot {
    void attack() {
        System.out.println("Attacking with Laser!");
    }
}

When you create a WarriorRobot, it can walk() AND attack()!

Advanced Concepts

1. The Diamond Problem

Imagine a child inherits from two parents who both have a method called cook().

Parent A cooks Pasta.
Parent B cooks Pizza.
Child: "Which cook() do I use?!"

This ambiguity is the Diamond Problem. Many languages (like Java) avoid this by disallowing Multiple Inheritance of classes. C++ allows it but requires careful handling.

2. Constructor Chaining

When you create a Child object, the Parent must be born first!

Child Constructor calls super() (Parent Constructor).
This chain goes all the way up to the root ancestor.

Java Example

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class Child extends Parent {
    Child() {
        super(); // Call Parent's constructor first!
        System.out.println("Child Created");
    }
}