Dart vs Kotlin: classes

classes.dart

abstract class Vehicle {
  String brand;  // Public
  int _year = 0; // Private
  int get year => _year; // Getter
  set year(int value) {  // Setter
    if (value < 0) {
      throw ArgumentError();
    }
    _year = value;
  }

  Vehicle(this.brand);

  void honk() { // Public method
    print("Tuut, tuut!");
  }
}

class Car extends Vehicle with Piloted {
  int numDoor;

  Car(String brand, this.numDoor) : super(brand);

  Car.mustang() :    // Named constructor
        numDoor = 2, // Initializer list
        super("Mustang");

  @override
  void honk() { // Override method
    print("Bepp, bepp!");
  }
}

mixin Piloted {
  void describePilot() => print('Pilots');
}

void main() {
  final myCar = Car("Tesla", 4);
  myCar.year = 2021;
  myCar.honk();
  myCar.describePilot();
  final mustang = Car.mustang();
}

classes.kt

abstract class Vehicle(
    var brand: String, // Public
) {
    private var _year: Int = 0 // Private
    var year: Int
        get() = _year // Getter
        set(value) {  // Setter
            if (value < 0) {
                throw IllegalArgumentException()
            }
            _year = value
        }

    open fun honk() { // Public method
        println("Tuut, tuut!")
    }
}

class Car(
    brand: String,
    var numDoor: Int
) : Vehicle(brand), PilotedContract by Piloted() {
    override fun honk() {
        println("Bepp, bepp!")
    }

    companion object { // Static method
        fun mustang() = Car("Mustang", 2)
    }
}

interface PilotedContract {
    fun describePilot()
}

class Piloted : PilotedContract {
    override fun describePilot() = println("Pilots")
}

fun main() {
    val myCar = Car("Tesla", 4)
    myCar.year = 2021
    myCar.honk()
    myCar.describePilot()
    val mustang = Car.mustang()
}