java中日期的计算问题

计算日期加减几天后的日期

public static String newDate(Date beginDate, int data) throws ParseException{
SimpleDateFormat dft = new SimpleDateFormat("yyyy-MM-dd");

Calendar date = Calendar.getInstance();
date.setTime(beginDate);
date.set(Calendar.DATE, date.get(Calendar.DATE) + data);
Date endDate = dft.parse(dft.format(date.getTime()));
return dft.format(endDate);
}

计算两个日期相差的天数

public static long getQuot(String time1, String time2){
long quot = 0;
SimpleDateFormat ft = new SimpleDateFormat("yyyy-MM-dd");
try {
Date date1 = ft.parse( time1 );
Date date2 = ft.parse( time2 );
quot = date1.getTime() - date2.getTime();
quot = quot / 1000 / 60 / 60 / 24;
} catch (ParseException e) {
e.printStackTrace();
}
return quot;
}