Explicit type declaration in Kotlin - Mini Project: Build & Apply

Explicit type declaration

📖 Scenario: You are working on a simple Kotlin program that stores information about a book. You want to practice explicitly declaring variable types to make your code clear and easy to understand.

🎯 Goal: Create variables with explicit type declarations for a book's title, author, and number of pages. Then print these details.

📋 What You'll Learn

Create a variable title with type String and value "The Hobbit"

Create a variable author with type String and value "J.R.R. Tolkien"

Create a variable pages with type Int and value 310

Print the book details in the format: Title: The Hobbit, Author: J.R.R. Tolkien, Pages: 310

💡 Why This Matters

🌍 Real World

Explicit type declarations help make code easier to read and maintain, especially in larger projects where knowing the exact type of data is important.

💼 Career

Many Kotlin jobs require clear and maintainable code. Knowing how to declare explicit types is a fundamental skill for writing professional Kotlin applications.

1

Create variables with explicit types

Create a variable called title with type String and value "The Hobbit".

Kotlin

# Your code here

Need a hint?

Use val to declare a read-only variable and specify the type after a colon.

2

Add more variables with explicit types

Create a variable called author with type String and value "J.R.R. Tolkien".
Create a variable called pages with type Int and value 310.

Kotlin

val title: String = "The Hobbit"
# Your code here

Need a hint?

Remember to declare the type explicitly for both variables.

3

Create a formatted string with explicit type

Create a variable called details with type String that combines title, author, and pages into the format: "Title: The Hobbit, Author: J.R.R. Tolkien, Pages: 310".

Kotlin

val title: String = "The Hobbit"
val author: String = "J.R.R. Tolkien"
val pages: Int = 310
# Your code here

Need a hint?

Use string templates with $ to insert variable values inside the string.

4

Print the book details

Print the variable details to display the book information.

Kotlin

val title: String = "The Hobbit"
val author: String = "J.R.R. Tolkien"
val pages: Int = 310
val details: String = "Title: $title, Author: $author, Pages: $pages"
# Your code here

Need a hint?

Use println(details) to show the book details on the screen.