showing a DatePickerDialog inside a Dialogfragment

Question

I created a DialogFragmentthat has an EditText, and when the user presses the EditText there is a new DatePickerDialog that suppose to pick a date from the user and then set it in the DialogFragment. I am having a hard time to do so:

1. The DatePickerDialog actually shows up but destroys the old DialogFragment. When I click ok/whatever I return to the activity.
2. I want to pass the date that I picked back to the fragment. It was easier if I wanted to pass it back to an activity because I can use getActivity() method. So how can I pass the date I picked back to the fragment that called the picker?

Main Fragment

public class NewWorkoutItemFragment extends android.app.DialogFragment implements
    View.OnClickListener {

private String mDate;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_new_workout_item, container, false);

    //A lot of code

    return view;
}

@Override
public void onClick(View v) {
switch (v.getId()){
    case R.id.NewWorkout_date_et:
        //Call to DatePickerDialog
        DialogFragment pickDate = new DatePickerFragment();
        pickDate.show(getFragmentManager(), "show");
}

public void setmDate(String mDate) {
    this.mDate = mDate;
}
}

DatePickerFragment

public class DatePickerFragment extends android.app.DialogFragment implements DatePickerDialog.OnDateSetListener {

@NonNull
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    // Use the current date as the default date in the picker.
    final Calendar c = Calendar.getInstance();
    int year = c.get(Calendar.YEAR);
    int month = c.get(Calendar.MONTH);
    int day = c.get(Calendar.DAY_OF_MONTH);

    // Create a new instance of DatePickerDialog and return it.
    return new DatePickerDialog(getActivity(), this, year, month, day);
}

@Override
public void onDateSet(DatePicker view, int year, int month, int dayOfMonth) {
String dateString = Integer.toString(dayOfMonth) +
                "/" + Integer.toString(month+1) +
                "/" + Integer.toString(year);
    //note- Return dateString back to NewWorkoutItemFragment, using setmDate
}
}

Answer 1

The solution isn't about the datepickerdialog at all. I had a switch-case in my fragment that manages the events of clicks. I accidentally forgot to put a break; after the case which caused a flow to the other events (one of them was dismiss();), and that's why the datepickerdialog also dismissed my fragment.