Introduction to Kotlin Data Classes

Kotlin data classes are a powerful feature that allows developers to create classes specifically for holding data. These classes automatically generate useful methods like equals(), hashCode(), and toString(), which makes them ideal for representing simple data structures. In this article, we will explore three diverse examples of Kotlin data classes that illustrate their practical use cases.

Example 1: User Profile Data Class

Context

In a typical application, you might need to manage user profiles. A data class can efficiently hold user information such as name, email, and age.

data class UserProfile(
    val name: String,
    val email: String,
    val age: Int
)

fun main() {
    val user = UserProfile(name = "Jane Doe", email = "jane.doe@example.com", age = 30)
    println(user)
}

Notes

• This data class is immutable, meaning once an instance is created, its properties cannot be changed.
• You can easily create a list of UserProfile objects to manage multiple users in your application.

Example 2: Product Data Class for E-commerce

Context

In e-commerce applications, products often have various attributes. A data class can represent a product, including its ID, name, price, and stock status.

data class Product(
    val id: Int,
    val name: String,
    val price: Double,
    var inStock: Boolean
)

fun main() {
    val product = Product(id = 101, name = "Wireless Mouse", price = 29.99, inStock = true)
    println(product)
}

Notes

• In this example, inStock is mutable, allowing you to update the stock status as needed.
• This structure can be easily extended to include more attributes, such as category or description.

Example 3: Book Data Class for a Library System

Context

For library management systems, a data class can help manage information about books, including title, author, and ISBN.

data class Book(
    val title: String,
    val author: String,
    val isbn: String,
    val publishedYear: Int
)

fun main() {
    val book = Book(title = "1984", author = "George Orwell", isbn = "978-0451524935", publishedYear = 1949)
    println(book)
}

Notes

• The publishedYear property could be useful for filtering books by publication date.
• Data classes can also implement interfaces, allowing for more complex behaviors if needed.

These examples of Kotlin data classes demonstrate their versatility and ease of use in different programming scenarios. Leveraging data classes can significantly enhance code readability and maintainability.