提取日期Datepicker Android

Question

I've been trying to extract the date that I get with the Datepicker as it says here The problem comes when I try to use a function that I've created (getDate), I can't call the method from the activity in order to obtain the string, because these method can't be resolved. Can anyone explain me why?

This is the code for the Datepicker that I have in my activity.

public static class DatePickerFragment extends DialogFragment
        implements DatePickerDialog.OnDateSetListener {
    private String date;
    @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);
    }

    public void onDateSet(DatePicker view, int year, int month, int day) {
         date=Integer.toString(year)+"-"+Integer.toString(month)+"-"+Integer.toString(day);
    }

    public String getDate(){
        return date;
    }
}


public void showDatePickerDialog(View v) {
    DialogFragment newFragment = new DatePickerFragment();
    newFragment.show(getSupportFragmentManager(), "datePicker");
   String date = newFragment.getDate();
}

Answer 1

Finally, I found a possible solution on this post Android - Date Picker - Obatin Value ,specially this comment:

declare Textview as public & static & call it on dateSet method by-className.textviewName.setText();

But I still don't understand the reason why I can't do what I initially wanted