Nested class independence from outer in Kotlin - Mini Project: Build & Apply

Nested class independence from outer in Kotlin

📖 Scenario: Imagine you are creating a simple app to manage books and their details. You want to organize your code by using a nested class inside a main class. This project will help you understand how a nested class in Kotlin works independently from its outer class.

🎯 Goal: You will create a Kotlin program with an outer class Book and a nested class Details. You will see how the nested class can be used without needing an instance of the outer class.

📋 What You'll Learn

Create an outer class called Book with a property title of type String.

Create a nested class inside Book called Details with a property author of type String.

Create an instance of the nested class Details without creating an instance of Book.

Print the author property of the nested class instance.

💡 Why This Matters

🌍 Real World

Nested classes help organize related code together, making it easier to manage and understand complex programs.

💼 Career

Understanding nested classes is useful for Kotlin developers working on Android apps or backend services where clean code structure is important.

1

Create the outer class Book with a title property

Create a class called Book with a property title of type String initialized to "Kotlin Programming".

Kotlin

# Your code here

Need a hint?

Use class Book to define the class and val title: String = "Kotlin Programming" to create the property.

2

Add a nested class Details with an author property

Inside the Book class, create a nested class called Details with a property author of type String initialized to "John Doe".

Kotlin

class Book {
    val title: String = "Kotlin Programming"
    // Your code here
}

Need a hint?

Define the nested class with class Details inside Book. Add the author property inside it.

3

Create an instance of the nested class Details without an outer class instance

Create a variable called details and assign it a new instance of the nested class Book.Details() without creating an instance of Book.

Kotlin

class Book {
    val title: String = "Kotlin Programming"
    class Details {
        val author: String = "John Doe"
    }
}

// Your code here

Need a hint?

Use Book.Details() to create the nested class instance without an outer class object.

4

Print the author property of the nested class instance

Write a println statement to display the author property of the details instance.

Kotlin

class Book {
    val title: String = "Kotlin Programming"
    class Details {
        val author: String = "John Doe"
    }
}

val details = Book.Details()

// Your code here

Need a hint?

Use println(details.author) to print the author name.