findViewById() may produce NullPointerException

Question

I have many of these calls:

(ListView) getView().findViewById(R.id.main_list_view);
(TextView) getView().findViewById(R.id.items_no);
....

and AndroidStudio tells me that they may procude a NullPointerException:

Method invocation getView().findViewById(R.id.main_list_view) may produce java.lang.NullPointerException less... (Ctrl+F1)

This inspection analyzes method control and data flow to report possible conditions that are always true or false, expressions whose value is statically proven to be constant, and situations that can lead to nullability contract violations.

Variables, method parameters and return values marked as @Nullable or @NotNull are treated as nullable (or not-null, respectively) and used during the analysis to check nullability contracts, e.g. report possible NullPointerException errors.

More complex contracts can be defined using @Contract annotation, for example:

@Contract("_, null -> null") — method returns null if its second argument is null @Contract("_, null -> null; _, !null -> !null") — method returns null if its second argument is null and not-null otherwise

@Contract("true -> fail") — a typical assertFalse method which throws an exception if true is passed to it

The inspection can be configured to use custom @Nullable @NotNull annotations (by default the ones from annotations.jar will be used)

Luckily everithing works, but is there an improvement to this code I can made?

Answer 1

This is a known issue in android.support.v7.app.AppCompatActivity and it has been fixed in v24.

https://code.google.com/p/android/issues/detail?id=203345

You won't have any issues with android.support.v4.app.FragmentActivity or android.app.Activity