Class declaration syntax in Kotlin - Mini Project: Build & Apply

Class declaration syntax

📖 Scenario: You are creating a simple program to represent a book in a library system.

🎯 Goal: Build a Kotlin class called Book with properties for the book's title and author.

📋 What You'll Learn

Create a class named Book

Add two properties: title and author of type String

Create an instance of Book with specific values

Print the book's title and author

💡 Why This Matters

🌍 Real World

Classes help organize data about real-world things like books, making programs easier to understand and maintain.

💼 Career

Understanding class declaration is fundamental for Kotlin developers building apps, especially for Android development.

1

Create the Book class with properties

Write a Kotlin class called Book with two properties: title and author, both of type String. Use the primary constructor to declare these properties.

Kotlin

class Book(val title: String, val author: String) {
    // Your code here
}

Need a hint?

Use class Book(val title: String, val author: String) to declare the class and its properties.

2

Create an instance of the Book class

Create a variable called myBook and assign it a new Book object with the title "The Hobbit" and author "J.R.R. Tolkien".

Kotlin

class Book(val title: String, val author: String)

// Your code here

Need a hint?

Use val myBook = Book("The Hobbit", "J.R.R. Tolkien") to create the instance.

3

Access the properties of the Book instance

Create two variables called bookTitle and bookAuthor and assign them the title and author properties of myBook respectively.

Kotlin

class Book(val title: String, val author: String)

val myBook = Book("The Hobbit", "J.R.R. Tolkien")

// Your code here

Need a hint?

Use val bookTitle = myBook.title and val bookAuthor = myBook.author to get the properties.

4

Print the book's title and author

Write a println statement to display the text: "Title: The Hobbit, Author: J.R.R. Tolkien" using the variables bookTitle and bookAuthor.

Kotlin

class Book(val title: String, val author: String)

val myBook = Book("The Hobbit", "J.R.R. Tolkien")

val bookTitle = myBook.title
val bookAuthor = myBook.author

// Your code here

Need a hint?

Use println("Title: $bookTitle, Author: $bookAuthor") to print the output.