public class MyActivity extends Activity {
    private Realm realm;
    private RealmResults<Person> allPersons;
    private RealmChangeListener realmListener = new RealmChangeListener() {
        @Override
        public void onChange(Realm realm) { //// <-- if RealmChangeListener is raw, this is Object
            // Just redraw the views. `allPersons` already contain the
            // latest data.
            invalidateView();
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        realm = Realm.getDefaultInstance();
        realm.addRealmChangeListener(listener); //// <-- it's called "addChangeListener"!
        allPerson = realm.where(Person.class).findAll(); // Create the "live" query result
        setupViews(); // Initial setup of views
        invalidateView(); // Redraw views with data
    }

    // ...
}