Interface definition in Go - Mini Project: Build & Apply

Interface definition

📖 Scenario: You are building a simple program to represent different types of vehicles. Each vehicle can describe itself by returning its type as a string.

🎯 Goal: Create an interface called Vehicle with a method Type() that returns a string. Then create two structs Car and Bike that implement this interface.

📋 What You'll Learn

Create an interface named Vehicle with a method Type() string

Create a struct named Car

Create a struct named Bike

Implement the Type() method for both Car and Bike to return their type as a string

Create variables of type Car and Bike

Use the Vehicle interface to call the Type() method on both variables

Print the results

💡 Why This Matters

🌍 Real World

Interfaces let you write code that works with different types in a uniform way, like handling different vehicles in a transport app.

💼 Career

Understanding interfaces is key for Go developers to build modular, testable, and maintainable software.

1

Create structs for vehicles

Create two structs called Car and Bike with no fields.

Go

# Your code here
// Define struct Car
// Define struct Bike

Hint

Use the type keyword to define structs with empty braces {}.

2

Define the Vehicle interface

Create an interface called Vehicle with a method Type() string.

Go

package main

type Car struct{}
type Bike struct{}

// Define interface Vehicle with method Type() string
# Your code here

Hint

Use type Vehicle interface { Type() string } to define the interface.

3

Implement the Type() method for Car and Bike

Write the Type() method for Car that returns "Car" and for Bike that returns "Bike".

Go

package main

type Car struct{}
type Bike struct{}

type Vehicle interface {
	Type() string
}

// Implement Type() for Car
// Implement Type() for Bike
# Your code here

Hint

Define methods with receiver types Car and Bike that return the correct string.

4

Use the Vehicle interface and print results

Create variables myCar of type Car and myBike of type Bike. Then create variables v1 and v2 of type Vehicle assigned to myCar and myBike. Finally, print the results of calling Type() on v1 and v2.

Go

package main

type Car struct{}
type Bike struct{}

type Vehicle interface {
	Type() string
}

func (c Car) Type() string {
	return "Car"
}

func (b Bike) Type() string {
	return "Bike"
}

func main() {
	// Create variable myCar of type Car
	// Create variable myBike of type Bike
	// Create variable v1 of type Vehicle assigned to myCar
	// Create variable v2 of type Vehicle assigned to myBike
	// Print v1.Type() and v2.Type()
# Your code here
}

Hint

Use var v1 Vehicle = myCar to assign the struct to the interface variable. Use println() to print the results.