common_helper/src/main/java/com/xiongyingqi/util/DateHelper.java
public static String getNextDay(String nowDate, int delay) {
        try {
            SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
            String mdate = "";
            Date d = strToDate(nowDate);
            long myTime = (d.getTime() / 1000) + delay * 24 * 60 * 60;
            d.setTime(myTime * 1000);
            mdate = format.format(d);
            return mdate;
        } catch (Exception e) {
            return "";
        }
    }
public static String getNextDay(String nowDate, int delay) {
        try {
            SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
            String mdate = "";
            Date d = strToDate(nowDate);
            long myTime = (d.getTime() / 1000) + delay * 24 * 60 * 60;
            d.setTime(myTime * 1000);
            mdate = format.format(d);
            return mdate;
        } catch (Exception e) {
            return "";
        }
    }
得到一个时间延后或前移几天的时间,nowdate为时间,delay为前移或后延的天数