What is a Kotlin Data Class?
A Kotlin data class is a special type of class designed to hold data. It automatically provides several useful methods, such as toString(), equals(), hashCode(), and copy(), without requiring you to write them yourself. This makes data classes particularly useful for creating simple classes that are primarily used to store values.
Key Features of Kotlin Data Classes
Primary Constructor: A data class must have at least one primary constructor parameter.
Properties: The primary constructor parameters must be marked as val or var to be considered properties of the data class.
Generated Methods: Kotlin automatically generates equals(), hashCode(), toString(), copy(), and componentN() functions for data classes.
Example
data class User(val name: String, val age: Int)
In this example, User is a data class with two properties: name and age. Kotlin will automatically generate the following methods for this class:
equals(): Checks if two instances of User are equal based on their properties.
hashCode(): Generates a hash code based on the properties.
toString(): Returns a string representation of the object.
copy(): Creates a copy of the object with optional modifications.
componentN(): Functions for destructuring declarations.
Usage
val user1 = User("Alice", 25)
val user2 = user1.copy(age = 26)
println(user1) // Output: User(name=Alice, age=25)
println(user2) // Output: User(name=Alice, age=26)
Data classes are ideal for scenarios where you need to store and manipulate data in a concise and readable manner. They help reduce boilerplate code and improve code readability and maintainability.
