1. Introduction

In this tutorial, we'll dive into two fundamental concepts in object-oriented programming: inheritance and polymorphism.

Inheritance allows one class to acquire the properties and methods of another class, enabling reusability and a way to add new features to an existing class without altering it.

Polymorphism allows methods to behave differently based on the object that they are acting upon. This allows a single method or operator to behave differently depending on the context.

By the end of this tutorial, you will understand the concept of inheritance and polymorphism, how to implement them in your code, and why they're crucial components of efficient and effective object-oriented programming.

Prerequisites

• Basic understanding of object-oriented programming (OOP) principles.
• Basic familiarity with a programming language that supports OOP (like Java, Python, or C++).

2. Step-by-Step Guide

Inheritance

Inheritance is a mechanism that allows one class to inherit the features (properties and methods) of another class. The class whose properties and methods are inherited is known as the parent or superclass, and the class that inherits these properties and methods is called the child or subclass.

Inheritance allows for code reusability and method overriding (which is a form of polymorphism).

Polymorphism

Polymorphism is an OOP principle that allows methods to behave differently, depending on the object/instance they're acting upon. In other words, a single method or operator can perform different actions depending on the context.

3. Code Examples

Inheritance

Consider a parent class Animal and a child class Dog:

// Parent class
class Animal {
    void eat() {
        System.out.println("eating...");
    }
}

// Child class
class Dog extends Animal {
    void bark() {
        System.out.println("barking...");
    }
}

class TestInheritance {
    public static void main(String args[]) {
        Dog d = new Dog();
        d.bark();
        d.eat(); // inherited method
    }
}

In the above example, the Dog class extends the Animal class, hence it inherits the eat() method. So a Dog object can call both bark() and eat() methods.

Expected output:

barking...
eating...

Polymorphism

Consider an Animal class and Dog and Cat classes that inherit from it:

// Parent class
class Animal {
    void sound() {
        System.out.println("The animal makes a sound");
    }
}

// Child classes
class Dog extends Animal {
    void sound() {
        System.out.println("The dog says: woof woof");
    }
}

class Cat extends Animal {
    void sound() {
        System.out.println("The cat says: meow");
    }
}

class TestPolymorphism {
    public static void main(String args[]) {
        Animal myDog = new Dog(); // Dog object
        Animal myCat = new Cat(); // Cat object

        myDog.sound();
        myCat.sound();
    }
}

In the above example, both Dog and Cat classes override the sound() method of the Animal class. Depending on the object calling the sound() method, different outputs are produced.

Expected output:

The dog says: woof woof
The cat says: meow

4. Summary

In this tutorial, we've covered the concepts of inheritance and polymorphism. We've learned how inheritance allows one class to acquire the features of another, and how polymorphism enables one method to behave differently based on the object it's acting upon.

To continue learning, consider exploring method overloading and overriding, abstract classes, and interfaces.

5. Practice Exercises

1. Create a Vehicle class with a drive() method. Then create Car and Bike classes that inherit from Vehicle and override the drive() method.

2. Create a Shape class with a draw() method. Then create Circle, Square and Triangle classes that inherit from Shape and override the draw() method.

Solutions and tips will vary based on the specifics of the exercise, but be sure to understand the process of creating classes, inheritance, and overriding methods. Practice makes perfect!