java - 安卓日历 : first and last day of week -> zero month

Question

我想获取本周第一个星期一和本周第一个星期五的日期。

我这样试过:

    Calendar calendarFirstDay = Calendar.getInstance(Locale.GERMANY);
    Calendar calendarLastDay = Calendar.getInstance(Locale.GERMANY);
    Date now = new Date();

    calendarFirstDay.setTime(now);
    calendarLastDay.setTime(now);
    calendarFirstDay.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
    calendarLastDay.set(Calendar.DAY_OF_WEEK, Calendar.FRIDAY);

    MyTextView.setText(calendarFirstDay.get(Calendar.DATE) + "." + calendarFirstDay.get(Calendar.MONTH) + "." + calendarFirstDay.get(Calendar.YEAR) + " - "  + calendarLastDay.get(Calendar.DATE) + "." + calendarLastDay.get(Calendar.MONTH) + "." + calendarLastDay.get(Calendar.YEAR));

如果我今天(2014 年 1 月 26 日，星期日)尝试这个脚本，输出如下:

20.0.2014 - 24.0.2014

正确的是 20.1.2014 - 24.1.2014

有人知道为什么我的月份是零吗？

Answer 1

From the JavaDocs :

Field number for get and set indicating the month. This is a calendar-specific value. The first month of the year in the Gregorian and Julian calendars is JANUARY which is 0; the last depends on the number of months in a year.

因此，第一个月(一月)的 MONTH 值为 0，而不是 1(如您所料)。

不过还有一个更好的解决方案:使用 DateFormat或 SimpleDateFormat将日期格式化为文本。这样一来，您就不必担心，让DateFormat 来处理它。例如:

DateFormat myFormat = new SimpleDateFormat("dd.MM.yyyy");
MyTextView.setText(
    myFormat.format(calendarFirstDay.getTime()) + " - " +
    myFormat.format(calendarLastDay.getTime())
);