How to initialize a variable in Kotlin with an Interfaced type? - kotlin

Question

I'm brand new to Kotlin. I wanted to try the create-react-kotlin-app since I'm a react developer currently and I want to explore Kotlin.
I'm having a tough time instaniating my variables. I'm trying to do this:
fun main(args: Array<String>) {
val rootDiv = document.getElementById("root")
val gm : GameUiProps
gm.numPlayers = 2
gm.cardArray = arrayOf("Card to be dealt", "Cards to be Dealt")
gm.playerArray = arrayOf("Player 1", "Player 2")
RBuilder.render(rootDiv) {
GameUi(gm)
}
}
My gm variable isn't being initialized and I can't figure how how to do it.
I need to initiazle my GameUi component with props, but I can't figure out how to do that.
So GameUiProps comes from my component
interface GameUiProps : RProps {
var numPlayers: Int
var playerArray: Array<String>
var cardArray: Array<String>
}
class GameUi(props: GameUiProps) : RComponent<GameUiProps, RState>(props) {
private fun RBuilder.createHands() {
var numPlayers = props.numPlayers
val handArray: ArrayList<Unit> = ArrayList()
while (numPlayers > 0) {
handArray.add(
handUi(
props.playerArray[numPlayers],
props.cardArray[numPlayers]
)
)
numPlayers--
}
}
override fun RBuilder.render() {
div {
h1("sweet") {
+"RKT"
}
div {
createHands()
}
}
}
}

Answer 1

Your GameUiProps is just an interface, so you cannot instantiate it directly.
What you have (val gm: GameUiProps) is just field declaration without assigning anything to it. You obviously cannot access nor write any properties to it.
You need to either create a simple implementation with constructor, or an anonymous object.
Class that declares all interface fields in the constructor:
class GameUiPropsImpl(
override var numPlayers: Int,
override var playerArray: Array<String>,
override var cardArray: Array<String>) : GameUiProps
then in your fun main:
val gm = GameUiPropsImpl(2, arrayOf("Player 1", "Player 2"), arrayOf("Card to be dealt", "Cards to be Dealt"))
Or using an anonymous class implementing the interface:
val gm = object: GameUiProps{
override var numPlayers = 2
override var playerArray = arrayOf("Player 1", "Player 2")
override var cardArray = arrayOf("Card to be dealt", "Cards to be Dealt")
}

Answer 2

It has been a while, but for anyone who might need this, you just need to assign the variable gm to an object of type GameUiProps. Below is what I would have done.
val gm = object : GameUiProps{
override var numPlayers = 2
override var cardArray = arrayOf("Card to be dealt", "Cards to be Dealt")
override var playerArray = arrayOf("Player 1", "Player 2")
}
Hope it helps!