Warning: 'onCreateView' always returns non-null type

Question

Today I found this warning in all my fragments:

Warning:(45, 12) 'onCreateView' always returns non-null type

onCreateView:

override fun onCreateView(inflater: LayoutInflater,
    container: ViewGroup?,
    savedInstanceState: Bundle?): View? {
    ...
}

The question is, what has changed and why?

Android Studio version - 4.1.1.

Answer 1

this is Kotlin warning, probably new lint check for helping you producing better quality code

your method returns declared View? , but as we know in most cases this method shouldn't return null View , so this ? (null safety) is redundant. just remove ? , declare your method returns just View (not null by default in Kotlin)

override fun onCreateView(inflater: LayoutInflater,
    container: ViewGroup?,
    savedInstanceState: Bundle?): View { // in here no "?"
    ...
}

btw. DOC is saying that this method may return null and Fragment behaves then just like some objects/data holder, without UI, just for proper retaining instance across Activity s lifecycle. but in that case dev won't be overriding onCreateView at all