Overriding methods with override in Kotlin - Mini Project: Build & Apply

Overriding methods with override

📖 Scenario: Imagine you are creating a simple app that manages different types of vehicles. Each vehicle can describe itself with a message. You will learn how to change this message for specific vehicle types by overriding a method.

🎯 Goal: Build a Kotlin program that defines a base class Vehicle with a method describe(). Then create a subclass Car that overrides the describe() method to provide a custom message. Finally, print the description from both classes.

📋 What You'll Learn

Create a base class called Vehicle with a method describe() that returns the string "This is a vehicle."

Create a subclass called Car that inherits from Vehicle

Override the describe() method in Car to return the string "This is a car." using the override keyword

Create instances of Vehicle and Car and print the result of calling describe() on each

💡 Why This Matters

🌍 Real World

Overriding methods is common when you want different types of objects to behave differently while sharing a common interface, like different vehicles describing themselves uniquely.

💼 Career

Understanding method overriding is essential for Kotlin developers working on apps that use inheritance and polymorphism to organize code cleanly and reuse functionality.

1

Create the base class Vehicle

Create a class called Vehicle with a method describe() that returns the string "This is a vehicle."

Kotlin

class Vehicle {
    // Your code here
}

Need a hint?

Define a class named Vehicle. Inside it, write a function describe() that returns the exact string.

2

Create the subclass Car

Create a class called Car that inherits from Vehicle

Kotlin

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

// Your code here

Need a hint?

Use class Car : Vehicle() to make Car inherit from Vehicle.

3

Override the describe() method in Car

Inside the Car class, override the describe() method using the override keyword to return the string "This is a car."

Kotlin

open class Vehicle {
    fun describe(): String {
        return "This is a vehicle."
    }
}

class Car : Vehicle() {
    // Your code here
}

Need a hint?

Remember to mark the base class method as open and use override in the subclass method.

4

Create instances and print descriptions

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

Kotlin

open class Vehicle {
    open fun describe(): String {
        return "This is a vehicle."
    }
}

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

// Your code here

Need a hint?

Create variables vehicle and car with Vehicle() and Car(). Use println() to show their descriptions.