Language Elements

Data Types

Kotlin Classes

Kotlin Operators

Kotlin Constructors

Kotlin Null Safety

Extension Functions

Lambda Functions

Object Oriented Kotlin

Data Classes

Coroutines

Kotlin Collections

Kotlin Data Structures

Kotlin Algorithms

Delegation

Lateinit and Lazy Initialization

Kotlin Scope Functions

Kotlin Key Words

Kotlin Example Codes

Kotlin Interview Questions

Kotlin offers a more concise and expressive way to declare data-holding classes compared to Java. It significantly reduces boilerplate by automatically generating commonly used methods such as getters, setters, and utility functions.

What is a Data Class in Kotlin?

A Kotlin class can be declared as a data class using the data keyword. This instructs the compiler to automatically generate several standard methods:

• equals() — for structural equality checks
• hashCode() — for use in hash-based collections
• toString() — for a readable string representation
• copy() — for creating modified copies of instances
• componentN() — for destructuring declarations

Define a data class by specifying its properties directly in the primary constructor.

Requirements for a Kotlin Data Class:

• The primary constructor must have at least one parameter, and each parameter must be marked as val or var.


• The class cannot be marked as open, abstract, sealed, or inner.


• The class can extend other classes or implement interfaces.

Example of a Kotlin Data Class:

data class Employer(val companyName: String, val marketValueInBillions: Int)

fun main() {
    val employer = Employer("TechCorp", 4)
    println("Company Name: ${employer.companyName}")
    println("Market Value (in billions): ${employer.marketValueInBillions}")
}
    

• The Employer class is declared with the data keyword.
• It contains two properties: companyName and marketValueInBillions.
• The compiler automatically generates useful methods like equals(), hashCode(), toString(), and copy().

This approach improves code readability and maintainability. Kotlin data classes are ideal for modeling simple data structures such as database entities, API response models, or UI state.