Came across a curious situation with AndroidView this morning. I have composable that renders a list of

AndroidView

. The

View

used for

AndroidView

is provided by a generic provider that takes in some input and outputs a

View

type.

@Composable
fun BasketItemsList(
    modifier: Modifier,
    basketItems: List<ProductState>,
    provider: ProductCard,
    interactionListener: ProductCardView.InteractionListener
) {
    LazyColumn(modifier = modifier) {
        items(basketItems) { product ->
            AndroidView(factory = { provider.view }) {
                Timber.tag("BasketItemsList").v(product.toString())
                provider.setup(product, interactionListener)
            }
        }
    }
}

With this sample, any interaction with the ProductCard view’s doesn’t update the screen. Logging shows that the state gets updated but the catch is that it’s only updated once per button. For example, I have a favourites button. Clicking it once pushes a state update only once, any subsequent clicks doesn’t propagate. Also the card itself doesn’t updates. It’s as if it was never clicked. Now changing the block of

AndroidView.update

to cast from the

ProductCard

interface to a concrete view type works as expected. All clicks propagate correctly and the card view gets updated to reflect the state.

@Composable
fun BasketItemsList(
    modifier: Modifier,
    basketItems: List<ProductState>,
    provider: ProductCard,
    interactionListener: ProductCardView.InteractionListener
) {
    LazyColumn(modifier = modifier) {
        items(basketItems) { product ->
            AndroidView(factory = { provider.view }) {
                Timber.tag("BasketItemsList").v(product.toString())
//                provider.setup(product, interactionListener)
                (it as ProductCardView).setup(product, interactionListener)
            }
        }
    }
}

What am I missing here? why does using

ProductCard

type not working while casting the view to it’s type is working?

I don’t think it’s a casting thing - in the first snippet you’re calling

provider.setup

, in the second you’re calling

it.setup

. In the first case it looks like you’re calling the method on the wrong object.

Both are the same object ..

provider

is a view that implements

ProductCard

. Something like

class ProductCardView: View(), ProductCardView {
   override val view: View = this
   override fun setup(...) {}
}

Welp I’m out of ideas. Maybe there’s some compiler magic where it treats the lambda parameter specially somehow, and so updates only work if you go through it? But idk

Yeah I am thinking some compiler magic as well. Thanks anyways!