Data classes

A Kotlin data class becomes a regular C# class, not a record class. Its Equals, GetHashCode, ToString, and Copy behave exactly as Kotlin's data class does. Kotlin's own componentN() destructuring functions are never exported, including on a Flow/StateFlow-typed constructor parameter.

For this declaration in Toy.kt:

data class Toy(
  val name: String,
  val color: String,
)

using var toy1 = new Toy("Mouse", "Gray");
using var toy2 = new Toy("Mouse", "Gray");

bool equal = toy1.Equals(toy2);   // true
string text = toy1.ToString();    // "Toy(name=Mouse, color=Gray)"

using var copy = toy1.Copy("Ball", "Red");
string name = copy.Name;          // "Ball"; toy1.Name is still "Mouse"

== compares references, not values; use Equals for Kotlin's structural equality. Copy returns a new, independently disposable Toy and takes every constructor parameter, since C# cannot replicate Kotlin's default-to-current-value parameters on copy(). There is no with-expression; call Copy(...) with the full argument list instead.

Data classes inside a sealed hierarchy get the same treatment; see Interfaces, abstract and sealed classes.

Last modified: 19 September 2026