I've been exploring Jetpack Compose lately and discovered this very weird scenario where my @Preview is not showing and Android Studio is literally showing blank empty. No warnings or errors are shown.
This happens when I add @PreviewParameter to my composable function parameter.
The stupid solution was… It turns out that I had my PreviewParameterProvider declared in private and turning it to public or simply removing the visibility modifier fixed it.
class MyProvider : PreviewParameterProvider<MyClass> {
...
}
This wasn't even documented.
I hope Google will make it clear in the documentation or at least give an error in Android Studio so developers won't encounter this frustrating and time-wasting scenario.
I had another issue causing the same behaviour.
@Preview
@Composable
fun MyComposablePreview(
@PreviewParameter(MyComposableStateProvider::class) state: MyComposableState
) = MyComposable(state)
@Preview
@Composable
fun MyComposablePreview(
@PreviewParameter(MyComposableStateProvider::class) state: MyComposableState
) {
MyComposable(state)
}