在java代码中如何得到n天的时间

String add_date(int n){

Calendar c = Calendar.getInstance();

c.add(Calendar.DAY_OF_MONTH, n); //可以算到n天后的时间

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

String send_date = sdf.format(c.getTime());

return send_date；

}

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String add_date(String send_date,int n){

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

Calendar c = Calendar.getInstance();

try {

Date date=sdf.parse(send_date);

c.setTime(date);

c.add(Calendar.DAY_OF_MONTH, renew_day);

String new_date=sdf.format(c.getTime());

return new_date;

} catch (ParseException e) {

e.printStackTrace();

}

}