Interface as contract mental model in C Sharp (C#) - Mini Project: Build & Apply

Interface as contract mental model

📖 Scenario: Imagine you are building a simple system for different types of vehicles. Each vehicle must be able to start and stop. We will use an interface to make sure every vehicle follows this rule.

🎯 Goal: You will create an interface called IVehicle that acts like a contract. Then you will create classes that follow this contract by implementing the interface. Finally, you will show how to use these classes through the interface.

📋 What You'll Learn

Create an interface called IVehicle with two methods: Start() and Stop().

Create a class called Car that implements the IVehicle interface.

Create a class called Bike that implements the IVehicle interface.

Create a variable of type IVehicle and assign it to instances of Car and Bike.

Call the Start() and Stop() methods on the IVehicle variable and print messages.

💡 Why This Matters

🌍 Real World

Interfaces are used in software to ensure different parts follow the same rules, like how different vehicles must be able to start and stop.

💼 Career

Understanding interfaces is important for writing clean, maintainable code and working with many programming frameworks and libraries.

1

Create the IVehicle interface

Create an interface called IVehicle with two methods: void Start() and void Stop().

C Sharp (C#)

// Your code here

Need a hint?

An interface is like a promise that classes will have certain methods.

2

Create the Car class implementing IVehicle

Create a class called Car that implements the IVehicle interface. Implement the Start() method to print "Car started" and the Stop() method to print "Car stopped".

C Sharp (C#)

public interface IVehicle
{
    void Start();
    void Stop();
}

// Your code here

Need a hint?

Use : IVehicle after the class name to implement the interface.

3

Create the Bike class implementing IVehicle

Create a class called Bike that implements the IVehicle interface. Implement the Start() method to print "Bike started" and the Stop() method to print "Bike stopped".

C Sharp (C#)

public interface IVehicle
{
    void Start();
    void Stop();
}

public class Car : IVehicle
{
    public void Start()
    {
        System.Console.WriteLine("Car started");
    }

    public void Stop()
    {
        System.Console.WriteLine("Car stopped");
    }
}

// Your code here

Need a hint?

Implement the interface methods just like in the Car class.

4

Use the IVehicle interface to control vehicles

Create a variable of type IVehicle called vehicle. Assign it to a new Car() instance. Call vehicle.Start() and vehicle.Stop(). Then assign vehicle to a new Bike() instance. Call vehicle.Start() and vehicle.Stop() again.

C Sharp (C#)

public interface IVehicle
{
    void Start();
    void Stop();
}

public class Car : IVehicle
{
    public void Start()
    {
        System.Console.WriteLine("Car started");
    }

    public void Stop()
    {
        System.Console.WriteLine("Car stopped");
    }
}

public class Bike : IVehicle
{
    public void Start()
    {
        System.Console.WriteLine("Bike started");
    }

    public void Stop()
    {
        System.Console.WriteLine("Bike stopped");
    }
}

// Your code here

Need a hint?

Use the interface type IVehicle to hold different vehicle objects and call their methods.