Map creation (mapOf, mutableMapOf) in Kotlin - Mini Project: Build & Apply

Create and Use Maps with mapOf and mutableMapOf in Kotlin

📖 Scenario: You are organizing a small library. You want to keep track of book titles and their authors using a map.

🎯 Goal: Build a Kotlin program that creates a map of books and authors, adds a new book, and then prints all entries.

📋 What You'll Learn

Create an immutable map using mapOf with given book-author pairs

Create a mutable map using mutableMapOf from the immutable map

Add a new book and author to the mutable map

Print all book titles and authors from the mutable map

💡 Why This Matters

🌍 Real World

Maps are useful to store pairs of related data, like book titles and authors, product names and prices, or usernames and emails.

💼 Career

Understanding how to create and manipulate maps is important for many programming jobs, especially when working with data collections and key-value pairs.

1

Create an immutable map of books and authors

Create an immutable map called books using mapOf with these exact entries: "1984" to "George Orwell", "Brave New World" to "Aldous Huxley", and "Fahrenheit 451" to "Ray Bradbury".

Kotlin

# Create an immutable map called books with the given book-author pairs
# Your code here

Need a hint?

Use mapOf with pairs like "key" to "value" inside parentheses.

2

Create a mutable map from the immutable map

Create a mutable map called mutableBooks using mutableMapOf and initialize it with the entries from the books map.

Kotlin

val books = mapOf("1984" to "George Orwell", "Brave New World" to "Aldous Huxley", "Fahrenheit 451" to "Ray Bradbury")
# Create a mutable map called mutableBooks from books
# Your code here

Need a hint?

Create an empty mutable map with mutableMapOf<String, String>() and then add all entries from books using putAll.

3

Add a new book and author to the mutable map

Add a new entry to mutableBooks with the key "The Hobbit" and the value "J.R.R. Tolkien".

Kotlin

val books = mapOf("1984" to "George Orwell", "Brave New World" to "Aldous Huxley", "Fahrenheit 451" to "Ray Bradbury")
val mutableBooks = mutableMapOf()
mutableBooks.putAll(books)
# Add the book "The Hobbit" by "J.R.R. Tolkien" to mutableBooks
# Your code here

Need a hint?

Use the bracket notation mutableBooks["The Hobbit"] = "J.R.R. Tolkien" to add a new entry.

4

Print all book titles and authors

Use a for loop with variables title and author to iterate over mutableBooks.entries and print each book and author in the format: "Title: [title], Author: [author]".

Kotlin

val books = mapOf("1984" to "George Orwell", "Brave New World" to "Aldous Huxley", "Fahrenheit 451" to "Ray Bradbury")
val mutableBooks = mutableMapOf()
mutableBooks.putAll(books)
mutableBooks["The Hobbit"] = "J.R.R. Tolkien"
# Print all books and authors in the specified format
# Your code here

Need a hint?

Use a for loop with for ((title, author) in mutableBooks.entries) and print with println("Title: $title, Author: $author").