Jetpack Compose：如何将列表项包装在卡片中

Question

I have a screen where I need to show a header and a list of items wrapped in a card view. The whole screen has to be scrollable (like shown in the image below).

I know how to do this with a scrollable Column but I want to be able to use a LazyColumn (because each list item will have its own ViewModel due to the complexity of the view and I thought LazyColumn will be more resources-efficient). For the header, I can use item and for the list, I can use items . Below is the code I tried:

@Composable
fun Screen(
  items: List<String>
) {
  Column(
    Modifier.fillMaxSize()
  ) {
    TopAppBar(title = { Text(text = "My Activity") })

    LazyColumn {

      // Header
      item {
        Text("Title", Modifier.padding(32.dp))
      }

      // I cannot use Box in this way here
      Box(Modifier.padding(32.dp)) {
        Card {
          items(items.size) {
            Text("Item $it")
          }
        }
      }
    }
  }
}

The problem with that code is that I cannot wrap the list items in a card view because Card is not a LazyListScope . Using LazyColumn, how can I wrap the list items in a Card?

Answer 1

You can define your "Card" as a single item containing nested items .

items being part of LazyListScope you need to use kotlin explicit this such as this@LazyColumn

@Composable
fun Screen(
    items: List<String>
)  {
    Column(
        Modifier.fillMaxSize()
    ) {
        TopAppBar(title = { Text(text = "My Activity") })
        LazyColumn( Modifier.fillMaxSize()) {

            // Header
            item {
                Text("Title", Modifier.padding(32.dp))
            }

            // Single item
            item {
                // Your Box list here
                Box(Modifier.padding(32.dp)) {
                    Card {
                        this@LazyColumn.items(items.size) {
                            Text("Item $it")
                        }
                    }
                }
            }
        }
    }
}