/**
 * Display dates correctly in grid
 */
public void updateCalendar(HashSet<Date> events)
{
    ArrayList<Date> cells = new ArrayList<>();
    Calendar calendar = (Calendar)currentDate.clone();

    // determine the cell for current month's beginning
    calendar.set(Calendar.DAY_OF_MONTH, 1);
    int monthBeginningCell = calendar.get(Calendar.DAY_OF_WEEK) - 2;

    // move calendar backwards to the beginning of the week
    calendar.add(Calendar.DAY_OF_MONTH, -monthBeginningCell);

    // fill cells
    while (cells.size() < DAYS_COUNT)
    {
        cells.add(calendar.getTime());
        calendar.add(Calendar.DAY_OF_MONTH, 1);
    }

    // update grid
    gridView.setAdapter(new CalendarAdapter(getContext(), cells, events));

    // update title
    SimpleDateFormat sdf = new SimpleDateFormat("EEEE,d MMM,yyyy");
    String[] dateToday = sdf.format(currentDate.getTime()).split(",");
    txtDateDay.setText(dateToday[0]);
    txtDisplayDate.setText(dateToday[1]);
    txtDateYear.setText(dateToday[2]);
}