Abstract classes and methods in Kotlin - Mini Project: Build & Apply

Abstract classes and methods

📖 Scenario: You are creating a simple program to represent different types of vehicles. Each vehicle has a way to describe itself, but the exact description depends on the type of vehicle.

🎯 Goal: Build an abstract class called Vehicle with an abstract method describe(). Then create two classes Car and Bike that inherit from Vehicle and provide their own description. Finally, print the descriptions of both vehicles.

📋 What You'll Learn

Create an abstract class called Vehicle

Add an abstract method describe() that returns a String

Create a class Car that inherits from Vehicle and implements describe()

Create a class Bike that inherits from Vehicle and implements describe()

Create instances of Car and Bike

Print the result of calling describe() on both instances

💡 Why This Matters

🌍 Real World

Abstract classes help organize code when you have different types of things that share some common behavior but also have their own specific details.

💼 Career

Understanding abstract classes and methods is important for designing clean and reusable code in many software development jobs.

1

Create the abstract class

Create an abstract class called Vehicle with an abstract method describe() that returns a String.

Kotlin

abstract class Vehicle {
    // Your code here
}

Need a hint?

Use the abstract keyword before the class and the method. The method should have no body.

2

Create the Car class

Create a class called Car that inherits from Vehicle and implements the describe() method to return the string "This is a car.".

Kotlin

abstract class Vehicle {
    abstract fun describe(): String
}

// Your code here

Need a hint?

Use class Car : Vehicle() to inherit and override fun describe() to provide the method body.

3

Create the Bike class

Create a class called Bike that inherits from Vehicle and implements the describe() method to return the string "This is a bike.".

Kotlin

abstract class Vehicle {
    abstract fun describe(): String
}

class Car : Vehicle() {
    override fun describe(): String {
        return "This is a car."
    }
}

// Your code here

Need a hint?

Similar to Car, inherit from Vehicle and override describe().

4

Create instances and print descriptions

Create an instance of Car called car and an instance of Bike called bike. Then print the result of calling describe() on both instances.

Kotlin

abstract class Vehicle {
    abstract fun describe(): String
}

class Car : Vehicle() {
    override fun describe(): String {
        return "This is a car."
    }
}

class Bike : Vehicle() {
    override fun describe(): String {
        return "This is a bike."
    }
}

// Your code here

Need a hint?

Create the instances with val car = Car() and val bike = Bike(). Use println() to print their descriptions.