Is there no smart cast in case of `OR`ed null chec...

# getting-started

[Lukasz Kalnik]

Is there no smart cast in case of `OR`ed null checks inside of if?

val selectedScene1: String? = // ...
val selectedScene2: String? = // ...
if (selectedScene1 != null || selectedScene2 != null) {
    val sceneToFind: String = selectedScene1 ?: selectedScene2!! // The !! are necessary to make this work
}

[Michael de Kaste]

a combination based smartcast isn't really possible since the nullability of one now relies on the nullability of the other. What you however can do is something like

listOfNotNull(selectedScene1, selectedScene2).firstOrNull() //on null, you're not in your 'if'. On value, you are.

[Lukasz Kalnik]

Smart solution, thank you!

[Lukasz Kalnik]

So the non-nullability in the line with ?: cannot be resolved at compile time if I understand this correctly.

[Lukasz Kalnik]

Although logically sceneToFind should always be non-nullable inside the if (even without the !!). But I suppose the nullability is resolved by type checker which doesn't follow the logic of the program but just statically compares resolved types.

[ephemient]

if you remove

if (selectedScene1 != null || selectedScene2 != null)

and replace it with

val sceneToFind: String? = selectedScene1 ?: selectedScene2
if (sceneToFind != null) {

then you will get effectively the same result, but safely

[Lukasz Kalnik]

True, that's also a good solution. 🙏