Даже без фрагмента одно действие может сделать это:
@Override protected void onSaveInstanceState (Bundle outState)
{
super.onSaveInstanceState (outState);
outState.putInt ("YEAR", mDatePicker.getYear ());
outState.putInt ("MONTH", mDatePicker.getMonth ());
outState.putInt ("DAY", mDatePicker.getDayOfMonth ());
}
@Override protected void onRestoreInstanceState (Bundle savedInstanceState)
{
super.onRestoreInstanceState (savedInstanceState);
mDatePicker.updateDate (savedInstanceState.getInt ("YEAR"),
savedInstanceState.getInt ("MONTH"),
savedInstanceState.getInt ("DAY"));
}