Enter the start time and end time of the week to get the week number minus 6 days and then calculate it.

Wrote sloppily

By entering the number of weeks, get the start time and end time of the selected week number

End time of the week (number of weeks * 7 = number of days ) Start time of the  week (number of weeks * 7 = number of days) 

 

Code

  /**
         *  输入周数  开始 42周*7 =   294-7
         */
        String startTime = getDateStr("2018-12-31", (294 - 7));
        /**
         *  输入周数  结束 42周*7 =   294-1
         */
        String stopTime = getDateStr("2018-12-31", 294 - 1);
        MyLog.e("周的开始时间____" + startTime);
        MyLog.e("周的结束时间____" + stopTime);
    }

    /**
     * @param day
     * @param dayAddNum
     * @return
     */
    public static String getDateStr(String day, long dayAddNum) {
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        Date nowDate = null;
        try {
            nowDate = df.parse(day);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        Date newDate2 = new Date(nowDate.getTime() + dayAddNum * 24 * 60 * 60 * 1000);
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
        String dateOk = simpleDateFormat.format(newDate2);
        return dateOk;
    }