How to set default focus item in Android jetpack Compose

Question

I have a screen with several focusable widgets for TV.

Every time I have to click the direction key then Box01 get focused.

Does anyone know how to set Box01 focused by default?

My Code:

@Composable
fun DefaultFocusSample(){
    Row(Modifier.padding(100.dp)) {
        FocusBox("Box01")
        Spacer(modifier = Modifier.padding(10.dp))
        FocusBox("Box02")
        Spacer(modifier = Modifier.padding(10.dp))
        FocusBox("Box03")
        Spacer(modifier = Modifier.padding(10.dp))
        FocusBox("Box04")
    }

}
@Composable
fun FocusBox(text:String){
    var color by remember { mutableStateOf(White) }
    Box(
        Modifier
            .onFocusChanged {
                color = if (it.isFocused) Green else White }
            .focusable()
            .border(2.dp,color)
    ){
        Text(text = text,
        modifier = Modifier.padding(10.dp))
    }
}

Answer 1

To manually bring focus to focusable, you can use FocusRequester, like this:

@Composable
fun FocusBox(text:String, requester: FocusRequester = FocusRequester()){
    var color by remember { mutableStateOf(Color.White) }
    Box(
        Modifier
            .focusRequester(requester)
            .onFocusChanged {
                color = if (it.isFocused) Color.Green else Color.White
            }
            .focusable()
            .border(2.dp, color)
    ) {
        Text(text = text,
            modifier = Modifier.padding(10.dp))
    }
}

Row(
    Modifier
        .background(Color.Yellow)
        .padding(10.dp)
) {
    val requester = FocusRequester()
    FocusBox("Box01", requester)
    LaunchedEffect(Unit) {
        requester.requestFocus()
    }
    Spacer(modifier = Modifier.padding(10.dp))
    FocusBox("Box02")
    Spacer(modifier = Modifier.padding(10.dp))
    FocusBox("Box03")
    Spacer(modifier = Modifier.padding(10.dp))
    FocusBox("Box04")
}

LaunchedEffect is a side effect, it'll be run only once when composable appears. Check out more in the documentation