PolymorphismToAvoidIf.kt

fun main() {
    val carDealer = CarDealer()
    println(carDealer.getSpeed(VehicleTypes.BUS))
}

class CarDealer {
    val map = HashMap<VehicleTypes, Vehicle>()

    init {
        map.put(VehicleTypes.CAR, Car())
        map.put(VehicleTypes.BUS, Bus())
        map.put(VehicleTypes.TRUCK, Truck())
    }

    fun getSpeed(vehicleType: VehicleTypes) = map.get(vehicleType)?.getSpeed()

    fun getNoOfSeats(vehicleType: VehicleTypes) = map.get(vehicleType)?.getSpeed()
}

class Car : Vehicle {
    override fun getSpeed() = 100
    override fun getNoOfSeats() = 4
}

class Bus : Vehicle {
    override fun getSpeed() = 200
    override fun getNoOfSeats() = 40
}

class Truck : Vehicle {
    override fun getSpeed() = 150
    override fun getNoOfSeats() = 5
}

interface Vehicle {
    fun getSpeed(): Int
    fun getNoOfSeats(): Int
}

enum class VehicleTypes {
    CAR, BUS, TRUCK
}

fun getNoOfSeats(vehicleType: VehicleTypes) = map.get(vehicleType)?.getNoOfSeats()