判断输入日期是该年的第一天

public static void main(String[] args) {try {dayOfYear("2002-01-02");} catch (ParseException e) {e.printStackTrace();}}private static void dayOfYear(String dateStart) throws ParseException{SimpleDateFormat sdf = new SimpleDateFormat("yyyy-HH-dd");        Date date = sdf.parse(dateStart);        Calendar calendar = Calendar.getInstance();         calendar.setTime(date);         int y = calendar.get(Calendar.DAY_OF_YEAR);        System.out.println("Day of year:" + y + " of " + date);}