Save reference to interface callback in DialogFragment after configurationChange

Question

I have an Activity that host a Fragment. In that Fragment I open a DialogFragment.

In the Fragment I call this function to show the dialog. Note that before showing the dialog I set an Interface defined in the DialogFragment.

private void showRatingDialog(){

        if (getActivity() != null) return;

        MyRatingDialog ratingDialog = new MyRatingDialog();
        ratingDialog.setOnRatingDialog(new MyRatingDialog.OnRatingDialog() {
            // some code
        });

        ratingDialog.show(getActivity().getSupportFragmentManager(), MyRatingDialog.TAG);        

}

My MyRatingDialog class:

public class MyRatingDialog extends DialogFragment{

    private OnRatingDialog onRatingDialog;

    public interface OnRatingDialog{
        void onSubmitRating(int rateSelected);
        void onCancelRating();
    }

    public void setOnRatingDialog(OnRatingDialog onRatingDialog) {
        this.onRatingDialog = onRatingDialog;
    }


    @NonNull
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {

        View layout = getActivity().getLayoutInflater().inflate(R.layout.dialog_rating, null, false);

        alertDialog = new AlertDialog.Builder(getActivity()).setView(layout).create();
        alertDialog.setCancelable(false);

        ratingStarComponent = (RatingStarComponent)layout.findViewById(R.id.rating_star_component);
        ratingStarComponent.setOnRateListener(new RatingStarComponent.OnRateListener() {
            @Override
            public void onRateClickListener(int starRate) {
                rate = starRate;
            }
        });

        Button rateButton = (Button)layout.findViewById(R.id.rate);
        rateButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (onRatingDialog!=null) { // this is null after a configuration change
                    onRatingDialog.onSubmitRating(rate, optionsSelected, commentsEditText.getText().toString());
                    alertDialog.dismiss();
                }
            }
        });

        ImageView closeButton = (ImageView)layout.findViewById(R.id.close);
        closeButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                alertDialog.dismiss();
            }
        });

        return alertDialog;


    }

    @Override
    public void onDismiss(DialogInterface dialog) {
        super.onDismiss(dialog);

        onRatingDialog.onCancelRating();

    }

}

The problem is that after a configurationChange like screen rotation or any other configurationChange, the interface onRatingDialog is null. My question is what is the best way/best practice to save the reference to onRatingDialog interface after a configurationChange? I wouldn't like to make the hosted Activity implements the interface, as I think it's more complex access to the dialog. By doing setRetainInstance(true) the dialog is closed after the configurationChange, so how can I mantain the dialog visible keeping the reference to the interface.

Thanks.

Answer 1

check out fragments doc.

find the below code on the page to implement a listener, Your Activity must implement the Listener you created in dialog. Then the Activity will be notified from dialogFragment and notify the concerned fragment from Activity.

public static class FragmentA extends ListFragment {
OnArticleSelectedListener mListener;
...
@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    try {
        mListener = (OnArticleSelectedListener) activity;
    } catch (ClassCastException e) {
        throw new ClassCastException(activity.toString() + " must implement OnArticleSelectedListener");
    }
}
...

You can also download the sample project here