Implement DialogFragment interface in OnClickListener

Question

I need to build a DialogFragment which returns user input from the dialog to an activity. The dialog needs to be called in an OnClickListener which gets called when an element in a listview gets clicked.
The return value of the DialogFragment (the input of the user) should be directly available in the OnClickListener in the activity.

I tried to implement this by sticking to the official docs: http://developer.android.com/guide/topics/ui/dialogs.html#PassingEvents

I need something like the following which doesn't work since I don't know how to make the anonymous OnClickListener implement the interface of the CustomNumberPicker class.
As far as I know implementing the interface is necessary in order to get data from the DialogFragment back to the Activity.

Main Activity:

public class MainAcitivity extends ActionBarActivity {
    [...]

    // ArrayAdapter of the Listview
    private class ListViewArrayAdapter extends ArrayAdapter<Exercise> {
        public ListViewArrayAdapter(Context context, ArrayList<Exercise> exercises) {
            super(context, 0, exercises);
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            [...]

            if (convertView == null) {
                convertView = LayoutInflater.from(getContext()).inflate(R.layout.item_workoutdetail, parent, false);
            }

            TextView tvSets = (TextView) convertView.findViewById(R.id.tvWorkoutExerciseSets);
            tvSets.setText(sets.toString());

            // OnClickListener for every element in the ListView
            tvSets.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    // This is where the Dialog should be called and
                    // the user input from the Dialog should be returned
                    DialogFragment numberpicker = new CustomNumberPicker();
                    numberpicker.show(MainActivity.this.getSupportFragmentManager(), "NoticeDialogFragment");
                }

                // Here I would like to implement the interface of CustomNumberPicker
                // in order to get the user input entered in the Dialog
            });

            return convertView;
        }
    }
}

CustomNumberPicker (basically the same as in the docs):

public class CustomNumberPicker extends DialogFragment {

    public interface NoticeDialogListener {
        public void onDialogPositiveClick(DialogFragment dialog);
        public void onDialogNegativeClick(DialogFragment dialog);
    }

    // Use this instance of the interface to deliver action events
    NoticeDialogListener mListener;

    // Override the Fragment.onAttach() method to instantiate the NoticeDialogListener
    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        // Verify that the host activity implements the callback interface
        try {
            // Instantiate the NoticeDialogListener so we can send events to the host
            mListener = (NoticeDialogListener) activity;
        } catch (ClassCastException e) {
            // The activity doesn't implement the interface, throw exception
            throw new ClassCastException(activity.toString()
                + " must implement NoticeDialogListener");
        }
    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        // Use the Builder class for convenient dialog construction
        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
        builder.setMessage("Sets")
            .setPositiveButton("set", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        // Return stuff here to the activity?
                    }
                })
                .setNegativeButton("cancle", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        // User cancelled the dialog
                    }
                });
        // Create the AlertDialog object and return it
        return builder.create();
    }
}

Answer 1

Something like this?

public class CustomNumberPicker extends DialogFragment {
    private NoticeDialogListener ndl;

    public interface NoticeDialogListener {
        public void onDialogPositiveClick(DialogFragment dialog);
        public void onDialogNegativeClick(DialogFragment dialog);
    }

    //add a custom constructor so that you have an initialised NoticeDialogListener
    public CustomNumberPicker(NoticeDialogListener ndl){
        super();
            this.ndl=ndl;
    }

    //make sure you maintain an empty constructor
    public CustomNumberPicker( ){
        super();
    }

    // Use this instance of the interface to deliver action events
    NoticeDialogListener mListener;

    // Override the Fragment.onAttach() method to instantiate the NoticeDialogListener
    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        //remove the check that verfis if your activity has the DialogListener Attached because you want to attach it into your list view onClick()
    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        // Use the Builder class for convenient dialog construction
        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
        builder.setMessage("Sets")
            .setPositiveButton("set", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        ndl.onDialogPositiveClick(dialog);
                    }
                })
                .setNegativeButton("cancle", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                       ndl.onDialogNegativeClick(dialog);
                    }
                });
        // Create the AlertDialog object and return it
        return builder.create();
    }
}

and then your listView onClick becomes:

tvSets.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    // This is where the Dialog should be called and
                    // the user input from the Dialog should be returned
                    // 
                    // 


                    DialogFragment numberpicker = new CustomNumberPicker(new NoticeDialogListener() {

            @Override
            public void onDialogPositiveClick(DialogFragment dialog) {
                //What you want to do incase of positive click

            }

            @Override
            public void onDialogNegativeClick(DialogFragment dialog) {
               //What you want to do incase of negative click

            }
        };);
                    numberpicker.show(MainActivity.this.getSupportFragmentManager(), "NoticeDialogFragment");
                }

                // Here I would like to implement the interface of CustomNumberPicker
                // in order to get the user input entered in the Dialog
            });

Do read the comments I have added.And it can even be further optimized because you really dont need an entire dialog instance to get the values you need.

EDIT a possible optimization could be:

Changing the Listener interface to :

public interface NoticeDialogListener {
        public void onDialogPositiveClick(String output);
        public void onDialogNegativeClick(String output);
       //or whatever form of output that you want
    }

Then modify the implemented methods accordingly.