可组合函数在timer.ontick中不起作用

Question

我是jetpack compose的新手，我已经创建了一个具有简单文本的可组合函数。我想在每次计时器达到timer.ontick函数时更新它但这行不通。任何帮助吗?

fun LKIDView(text : String, onLKIDViewChange: (String) -> Unit) {
var lkidState by remember { mutableStateOf("Default") }
val onlkidChange={text : String -> lkidState = text}
Column(
horizontalAlignment = Alignment.CenterHorizontally, modifier = Modifier
.fillMaxWidth()
.background(Color(0xFF7DCEA0))
) {
Text(
text = lkidState,
// modifier = Modifier.fillMaxWidth(),
fontSize = 20.sp,
fontWeight = FontWeight.Bold,
fontFamily = FontFamily.SansSerif,
//
)
}
}`
`
My ontimer.tick looks like this
`val timer = object : CountDownTimer(Gtime, Ttime) {
var lkidviewState = remember { mutableStateOf("Landkreis/Kreeisfreie Stadt") }
val onTextChange={text : String -> lkidviewState.value = text}
override fun onTick(millisUntilFinished: Long) {
Log.e("TimerTick - ", "Tick ")
LKIDView(text =lkidviewState.value , onLKIDViewChange = onTextChange)
// lkidviewState.value = "dsfdsfdsf"`}`
Android Studio says composable invocation can only happen from the context of a composable function
timer runs - the code did not update the ui

Answer 1

Compose不是这样工作的。

您不能在CountDownTimer中调用可组合对象来显示更新后的值。
您必须使用状态(lkidState)，然后CountDownTimer必须更新此值。

val lkidState = remember {
mutableStateOf(0)
}
val timer = object : CountDownTimer(0, 1000) {
override fun onTick(millisUntilFinished: Long) {
lkidState.value = millisUntilFinished
}
//...
}
Text(text = lkidState.value.toString())

最后注意，我会使用其他选项而不是CountDownTimer，比如副作用。