code: public static Date dateReservedQuarter000(int year, int quarter) {
          Calendar calendar = Calendar.getInstance();
          calendar.set(Calendar.YEAR, year);
          if (quarter <= 1) {
              calendar.set(Calendar.MONTH, Calendar.JANUARY);
          } else if (quarter == 2) {
              calendar.set(Calendar.MONTH, Calendar.APRIL);
          } else if (quarter == 3) {
              calendar.set(Calendar.MONTH, Calendar.JULY);
          } else {
              calendar.set(Calendar.MONTH, Calendar.OCTOBER);
          }
          return dateReservedMonth000(calendar);
      }
docs: 获取指定年,季度的最初时刻
  
  @param year    年份
  @param quarter 季度
  @return 指定年, 季度的最初时刻日期对象