private static boolean isPentecoste(Calendar calendar) {

int year = calendar.get(Calendar.YEAR);
Calendar easter = findEaster(year);

easter.add(Calendar.DAY_OF_MONTH, 50);

// easter is now the first day of pentecoste
int dateMonth = calendar.get(Calendar.MONTH);
int dateDay = calendar.get(Calendar.DAY_OF_MONTH);
int pentecosteMonth = easter.get(Calendar.MONTH);
int pentecosteDay = easter.get(Calendar.DAY_OF_MONTH);

return (dateMonth == pentecosteMonth && dateDay == pentecosteDay);
}