//计算某个日期n天前后的日期，并指定打印格式。正值表示向后计算，负数表示向前计算。public static String getBeforeOrAfterDay(String startDay, int dayCount) throws ParseException { SimpleDateFormat sf = new SimpleDateFormat("yyyyMMdd"); Calendar calendar = Calendar.getInstance(); Date date = sf.parse(startDay); calendar.setTime(date); calendar.add(calendar.DATE, dayCount); Date day = calendar.getTime(); String returnDay = sf.format(day); return returnDay;}
2、计算某个日期过去N天所有日期的集合
public static String[] getLastDays(String day, int dayCount) throws ParseException { String[] days = new String[dayCount]; for (int i = 0; i < dayCount; i++) { days[i] = getBeforeOrAfterDay(day, -i); } return days;}
3、判断某个日期是星期几
public static int getWeekDay(String day) throws ParseException { SimpleDateFormat sf = new SimpleDateFormat("yyyyMMdd"); Calendar calendar = Calendar.getInstance(); Date date = sf.parse(day); calendar.setTime(date); //注意1：星期天，2：星期一.....7：星期六 return calendar.get(Calendar.DAY_OF_WEEK);}
