Android nullable annotation not recognized in Kotlin

Question

Android source code suggests that findViewById can return null:

@Nullable
public final <T extends View> T findViewById(@IdRes int id) {
    if (id == NO_ID) {
        return null;
    }
    return findViewTraversal(id);
}

But when calling it from Kotlin, compiler doesn't complain about nullability when using this way:

private lateinit var swipeRefreshLayout: SwipeRefreshLayout
...
swipeRefreshLayout = view.findViewById(R.id.swiperefresh)

As I can guess, this Nullable annotation is from android pacakge and there are also other Nullable annotations, that Kotlin does recognize well. Is it Kotlin/IDE related issue or should Android team do something about this?

Answer 1

findViewById is using generics. We explicitly provide the type it should return. If we rewrite the init line, compiler would complain about nullability.

swipeRefreshLayout = view.findViewById<SwipeRefreshLayout?>(R.id.swiperefresh)