How to update an item in array with a lazy column item change?-CodePudding

I have a todo list in Jetpack Compose displayed in LazyColumn.

data class TodoItem(val id: Int, val title: String, var urgent: Boolean = false)

val todoList = listOf(
    TodoItem(0, "My First Task"),
    TodoItem(1, "My Second Task which is really very very long. Super long. I mean longer than a line.", true),
    TodoItem(2, "My Third Task"),
)

@Composable
fun MyTodoListView() {
    LazyColumn(modifier = Modifier.fillMaxHeight()) {
        items(items = todoList, itemContent = { item ->
            var checked by remember { mutableStateOf(item.urgent) }
            Row(modifier = Modifier.fillMaxWidth(),
                verticalAlignment = Alignment.CenterVertically
            ) {
                Text(
                    modifier = Modifier.weight(1f).padding(8.dp),
                    text = item.title)
                Checkbox(
                    checked = checked,
                    onCheckedChange = {
                        checked = it
                        item.urgent = it
                    }
                )
            }
        })
    }
}

When I plan to update the value (through checkbox), I'll have to update is with a separate mutableState variable

onCheckedChange = {
    checked = it
    item.urgent = it
}

Is there a way to make it more direct, with only one variable to change instead of having to change both checked and item.urgent?

CodePudding user response：

You can use an observable MutableList (like a SnapshotStateList) and then update the items by creating a copy.

Something like:

val todoList = remember {
    listOf<TodoItem>(
        TodoItem(0, "My First Task"),
        //...
    ).toMutableStateList()
}


LazyColumn(modifier = Modifier.fillMaxHeight()) {
    items(items = todoList, itemContent = { item ->

        //...
        Checkbox(
            checked = item.urgent,
            onCheckedChange = {
                //checked = it
                val index = todoList.indexOf(item)
                todoList[index] = todoList[index].copy(urgent = it)
            }
        )
        
    })
 }