计算几天后的日子

public static String getday(String date, int i) throws ParseException{
  SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
  Date sDate = sdf.parse(date);
  String time ="";
  sDate.setDate(sDate.getDate()+i);
  time= sdf.format(sDate);
  return time;
 }