Testing scope functions and lambdas in Kotlin - Mini Project: Build & Apply

Testing scope functions and lambdas

📖 Scenario: You are working on a Kotlin program that manages a list of book titles. You want to practice using Kotlin's scope functions and lambdas to manipulate and display this list in a clean and readable way.

🎯 Goal: Build a Kotlin program that creates a list of book titles, uses a scope function to filter and transform the list, and then prints the final result using a lambda expression.

📋 What You'll Learn

Create a list of book titles with exact values

Use a scope function to filter and transform the list

Use a lambda expression to print each book title

Follow exact variable names and function calls as instructed

💡 Why This Matters

🌍 Real World

Scope functions and lambdas help write clean and readable Kotlin code when working with collections and objects.

💼 Career

Understanding scope functions and lambdas is essential for Kotlin developers, especially in Android app development and backend services.

1

Create the list of book titles

Create a val called books and assign it a list containing these exact strings: "Kotlin Basics", "Advanced Kotlin", "Kotlin Coroutines", "Android Development".

Kotlin

# Create the list of book titles
# Your code here

Need a hint?

Use listOf() to create the list with the exact book titles.

2

Add a filter threshold variable

Create a val called minLength and set it to 15. This will be used to filter book titles longer than this length.

Kotlin

val books = listOf("Kotlin Basics", "Advanced Kotlin", "Kotlin Coroutines", "Android Development")
# Create the minLength variable
# Your code here

Need a hint?

Just create a simple integer variable named minLength with value 15.

3

Use a scope function to filter and transform

Use the books list and call run on it. Inside the run lambda, filter the list to keep only titles with length greater than minLength, then map each title to uppercase. Assign the result to a val called filteredBooks.

Kotlin

val books = listOf("Kotlin Basics", "Advanced Kotlin", "Kotlin Coroutines", "Android Development")
val minLength = 15
# Use run to filter and map books
# Your code here

Need a hint?

Use run on books, then inside the lambda use filter and map with lambdas.

4

Print the filtered book titles

Use filteredBooks.forEach with a lambda that prints each book title exactly as it is.

Kotlin

val books = listOf("Kotlin Basics", "Advanced Kotlin", "Kotlin Coroutines", "Android Development")
val minLength = 15
val filteredBooks = books.run {
    filter { it.length > minLength }
        .map { it.uppercase() }
}
# Print each filtered book title
# Your code here

Need a hint?

Use forEach on filteredBooks and print each item inside the lambda.