Date picker fragment on a dialog which takes inputs from a specific field, parses date strings according to the system's preferred locale and formats its own output too in the same locale-sensitive format.

DatePickerDialogFragment.java

package com.tghsistemas.ispark.fragment;

import android.app.DatePickerDialog;
import android.app.Dialog;
import android.os.Bundle;
import android.support.v4.app.DialogFragment;
import android.widget.DatePicker;
import android.widget.EditText;
import com.tghsistemas.ispark.util.DateUtil;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

/**
 * Date picker fragment on a dialog which takes inputs from a specific field, parses date strings
 * according to the system's preferred locale and formats its own output too in the same locale-sensitive
 * format.
 *
 * @author Eduardo Naveda
 */
public class DatePickerDialogFragment extends DialogFragment implements
        DatePickerDialog.OnDateSetListener {

    /**
     * Input field for the date picker.
     */
    private EditText field;

    /**
     * Constructor for a new date picker dialog fragment.
     *
     * @param field Input field for the date picker.
     */
    public DatePickerDialogFragment(EditText field) {
        this.field = field;
    }

    /**
     * If input {@link #field}'s content is in the preferred locale format, the date picker
     * parses the string and uses the date as default, else it uses today's date.
     *
     * @param savedInstanceState bundle containing saved state.
     * @return Date picker dialog.
     */
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        String inputDateString = field.getText().toString();
        Calendar calendar = Calendar.getInstance();
        Date today = new Date();
        try {
            Date inputDate = android.text.format.DateFormat.getDateFormat(getActivity()).parse(inputDateString);
            calendar.setTime(inputDate);

            return new DatePickerDialog(getActivity(), this,
                    calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH),
                    calendar.get(Calendar.DAY_OF_MONTH));
        } catch (ParseException e) {
            calendar.setTime(today);
            int year = calendar.get(Calendar.YEAR);
            int month = calendar.get(Calendar.MONTH);
            int day = calendar.get(Calendar.DAY_OF_MONTH);

            return new DatePickerDialog(getActivity(), this, year, month,
                    day);
        }
    }

    /**
     * Sets the date to the input {@link #field}.
     */
    @Override
    public void onDateSet(DatePicker view, int year, int month, int day) {
        Calendar calendar = Calendar.getInstance();
        calendar.set(year, month, day, 0, 0, 0);
        field.setText(android.text.format.DateFormat.getDateFormat(getActivity()).format(calendar.getTime()));
    }
}