How to fix getActionBar method may produce java.lang.NullPointerException

Question

I am using a toolbar as my actionbar in an activity. I am trying to add the method getActionBar().setDisplayHomeAsUpEnabled(true); to the Activity.java file fo

Answer 1

I created a generic class such as:

public final class Cast
{
    private Cast() {}

    /**
     * Helps to eliminate annoying NullPointerException lint warning.
     */
    @android.support.annotation.NonNull
    public static <T> T neverNull(T value)
    {
        return value;
    }
}

then I can use it for any call with NullPointerException warning for which I am sure that it will never happen, e.g.

final ActionBar actionBar = Cast.neverNull(getSupportActionBar());
actionBar.setDisplayHomeAsUpEnabled(true);
actionBar.setHomeButtonEnabled(true);

P.S. don't forget to add "com.android.support:support-annotations" to your gradle file.

Answer 2

Try this :

private ActionBar getActionBar() {
    return ((AppCompatActivity) getActivity()).getSupportActionBar();
}