Calendar在CalendarCalendarView中返回错误的MONTH，YEAR和DAY_OF_MONTH

我正在使用MaterialCalendarView作为我的应用日历 . 我想阅读用户点击日历上的下一个/上一个的月份和年份 . 这是我的代码：

calendarView = (CalendarView) view.findViewById(R.id.calendarView);
calendarView.setOnPreviousButtonClickListener(new OnNavigationButtonClickListener() {
           @Override
           public void onClick() {
               Calendar calendar = calendarView.getCurrentPageDate();
               int previousMonth = calendar.MONTH;
               int previousYear = calendar.YEAR;
               Log.i(TAG, "--- previous month: " + previousMonth + "/"  + previousYear + " - " + calendar);
           }
       });

calendarView.setOnForwardButtonClickListener(new OnNavigationButtonClickListener() {
           @Override
           public void onClick() {
               Calendar calendar = calendarView.getCurrentPageDate();
               int nextMonth = calendar.MONTH;
               int nextYear = calendar.YEAR;
               Log.i(TAG, "--- next month: " + nextMonth + "/" + nextYear +  " - " + calendar);
           }
       });

但是，当我单击下一个/上一个箭头时，返回给我的MONTH和YEAR值不正确 . 例如，在这个例子中它的JAN 20188.上个月应该是11，年应该是2017年，下个月应该是1和2018年 .

但是，对于之前单击日志，我看到：

I / CalendarFragment：---上个月：2/1 - java.util.GregorianCalendar [time =？，areFieldsSet = false，areAllFieldsSet = true，lenient = true，zone = java.util.SimpleTimeZone [id = GMT，offset = 0，dstSavings = 3600000，useDaylight =假，startYear = 0，STARTMODE = 0，startMonth = 0，朝九特派= 0，startDayOfWeek = 0，开始时间= 0，startTimeMode = 0，endMode = 0，endMonth = 0，endday指定= 0 ，一个endDayOfWeek = 0，结束时间= 0，endTimeMode = 0]，Firstdayofweek可= 1，minimalDaysInFirstWeek = 1，ERA = 1，YEAR = 2017，月= 11，WEEK_OF_YEAR = 1，WEEK_OF_MONTH = 1，DAY_OF_MONTH = 1，DAY_OF_YEAR = 1， DAY_OF_WEEK = 3，DAY_OF_WEEK_IN_MONTH = 1，AM_PM = 0，HOUR = 0，HOUR_OF_DAY = 0，MINUTE = 0，SECOND = 0，微差= 0，ZONE_OFFSET = 0，DST_OFFSET = 0]

下次点击我看到：

I / CalendarFragment：---下个月：2/1 - java.util.GregorianCalendar [time =？，areFieldsSet = false，areAllFieldsSet = true，lenient = true，zone = java.util.SimpleTimeZone [id = GMT，offset = 0，dstSavings = 3600000，useDaylight =假，startYear = 0，STARTMODE = 0，startMonth = 0，朝九特派= 0，startDayOfWeek = 0，开始时间= 0，startTimeMode = 0，endMode = 0，endMonth = 0，endday指定= 0 ，一个endDayOfWeek = 0，结束时间= 0，endTimeMode = 0]，Firstdayofweek可= 1，minimalDaysInFirstWeek = 1，ERA = 1，YEAR = 2018，月= 1，WEEK_OF_YEAR = 1，WEEK_OF_MONTH = 1，DAY_OF_MONTH = 1，DAY_OF_YEAR = 1， DAY_OF_WEEK = 3，DAY_OF_WEEK_IN_MONTH = 1，AM_PM = 0，HOUR = 0，HOUR_OF_DAY = 0，MINUTE = 0，SECOND = 0，微差= 0，ZONE_OFFSET = 0，DST_OFFSET = 0]

如果看到日志，则日历实例值的确具有MONTH和YEAR . 但是当我在外面访问它时返回2和1.为什么？

当我执行setOnDayClickListener（）时，会发生同样的事情

calendarView.setOnDayClickListener(new OnDayClickListener() {
            @Override
            public void onDayClick(EventDay eventDay) {
                Calendar clickedDayCalendar = eventDay.getCalendar();
                Log.i(TAG, "------- clicked day: " + clickedDayCalendar.DAY_OF_MONTH + " - " + clickedDayCalendar);

            }
        });

无论我在1月点击哪一天，它给我点击了一天为5.这是日志：

I / CalendarFragment：-------点击日：5 - java.util.GregorianCalendar [time =？，areFieldsSet = false，areAllFieldsSet = true，lenient = true，zone = java.util.SimpleTimeZone [id = GMT ，偏移= 0，dstSavings = 3600000，useDaylight =假，startYear = 0，STARTMODE = 0，startMonth = 0，朝九特派= 0，startDayOfWeek = 0，开始时间= 0，startTimeMode = 0，endMode = 0，endMonth = 0，endday指定= 0，一个endDayOfWeek = 0，结束时间= 0，endTimeMode = 0]，Firstdayofweek可= 1，minimalDaysInFirstWeek = 1，ERA = 1，YEAR = 2018，MONTH = 0，WEEK_OF_YEAR = 2，WEEK_OF_MONTH = 2，DAY_OF_MONTH = 12，DAY_OF_YEAR = 12，DAY_OF_WEEK = 6，DAY_OF_WEEK_IN_MONTH = 2，AM_PM = 0，HOUR = 10，HOUR_OF_DAY = 0，MINUTE = 0，SECOND = 0，MILLISECOND = 0，ZONE_OFFSET = 0，DST_OFFSET = 0] I / CalendarFragment：---- ---点击日：5 - java.util.GregorianCalendar [time =？，areFieldsSet = false，areAllFieldsSet = true，lenient = true，zone = java.util.SimpleTimeZone [id = GMT，offset = 0，dstSavings = 3600000， useDaylight =假，startYear = 0，STARTMODE = 0，startMonth = 0，朝九特派= 0，startDayOfWeek = 0，开始时间= 0，startTimeMode = 0，endMode = 0，endMonth = 0，endday指定= 0，一个endDayOfWeek = 0，结束时间= 0， endTimeMode = 0]，Firstdayofweek可= 1，minimalDaysInFirstWeek = 1，ERA = 1，YEAR = 2018，MONTH = 0，WEEK_OF_YEAR = 3，WEEK_OF_MONTH = 3，DAY_OF_MONTH = 20，DAY_OF_YEAR = 20，DAY_OF_WEEK = 7，DAY_OF_WEEK_IN_MONTH = 3，AM_PM = 1，HOUR = 3，HOUR_OF_DAY = 0，MINUTE = 0，SECOND = 0，微差= 0，ZONE_OFFSET = 0，DST_OFFSET = 0]

知道为什么会这样吗？或者是什么导致了它？