Can I use object properties as a mutableState in kotlin compose? - kotlin

Question

The code has been changed and reduced for this question!
I have a class called "Game" and I want to show in compose the dices value. And I want to update the composable with the new value every time a new turn is started and when that turn ends.
class Game (val board: Board, var player1: Player, var player2: Player) {
var dices = Dices()
}
class Dices (var first: Int = 0, var second: Int = 0) {
fun rollDices() {
first = rollDice() //Returns a value between 1 and 6
second = rollDice()
}
fun resetDices() {
first = 0
second = 0
}
fun areEqual() = first == second
}
I have the composable function "gameView" which calls "diceView", that is a composable function, which makes 2 boxes and puts the dices value on them.
Because "dices" is an object it doesn't get a new reference, neither does it update itself and neither can I change the value because it is inside the function.
#Composable
fun gameView(game: Game) {
paintBoard(game.board)
val dices by remember {mutableStateOf(game.dices)}
diceView(dices = dices, onClick = { game.newTurn()})
}
Any ideas on how to solve this?

Answer 1

If you update class with MutableState your Composables that listen these values will trigger recomposition any of these values change
class Dices(first: Int = 0, second: Int = 0) {
var firstDice by mutableStateOf(first)
var secondDice by mutableStateOf(first)
fun rollDices() {
firstDice = rollDice() //Returns a value between 1 and 6
secondDice = rollDice()
}
fun resetDices() {
firstDice = 0
secondDice = 0
}
fun areEqual() = firstDice == secondDice
}
Example
Column(modifier = Modifier.fillMaxSize()) {
val dices = remember { Dices(1, 1) }
Text("Dice1: ${dices.firstDice}")
Text("Dice2: ${dices.secondDice}")
Button(onClick = { dices.rollDices() }) {
Text("Roll")
}
Button(onClick = { dices.resetDices() }) {
Text("Reset")
}
}