安卓 Java获取前一周的日期列表

Question

在根据指定日期获取前一周的日期列表时，我遇到了一些问题。这是我的密码：

        SimpleDateFormat formatter = new SimpleDateFormat("EEE MMM dd");
        Date refDate = null;
        try {
            refDate = formatter.parse("Sun Aug 05");
        } catch (ParseException e) {
            e.printStackTrace();
        }
        Date[] days = reservationViewModel.getDaysOfWeek(refDate, Calendar.getInstance().getFirstDayOfWeek());
        for (Date day : days) {
            // display            
        }

以及获取日期列表的代码：

public static Date[] getDaysOfWeek(Date refDate, int firstDayOfWeek) {
    Calendar calendar = Calendar.getInstance();
    calendar.setTime(refDate);
    calendar.set(Calendar.DAY_OF_WEEK, firstDayOfWeek);
    Date[] daysOfWeek = new Date[7];
    for (int i = 0; i < 7; i++) {
        daysOfWeek[i] = calendar.getTime();
        calendar.add(Calendar.DAY_OF_MONTH, 1);
    }
    return daysOfWeek;
}

然而，我得到的结果是：

Sun Aug 02
Mon Aug 03
Tue Aug 04
Wed Aug 05
Thu Aug 06
Fri Aug 07
Sat Aug 08

日期都错了。应该从7月29日到8月4日。有什么想法吗？谢谢

Answer 1

使用Calendar.WEEK_OF_YEAR将时间从给定日期移到前一周。代码类似于calendar.set(Calendar.WEEK_OF_YEAR, calendar.get(Calendar.WEEK_OF_YEAR) - 1);

所以在你的情况下是这样的

public static Date[] getDaysOfWeek(Date refDate, int firstDayOfWeek) {
    Calendar calendar = Calendar.getInstance();
    calendar.setTime(refDate);
    calendar.set(Calendar.DAY_OF_WEEK, firstDayOfWeek);
    calendar.set(Calendar.WEEK_OF_YEAR, calendar.get(Calendar.WEEK_OF_YEAR) - 1);
    Date[] daysOfWeek = new Date[7];
    for (int i = 0; i < 7; i++) {
        daysOfWeek[i] = calendar.getTime();
        calendar.add(Calendar.DAY_OF_MONTH, 1);
    }
    return daysOfWeek;
}

---

获得前7天

public static Date[] getPrevious7Days(Date refDate) {
    Calendar calendar = Calendar.getInstance();
    int currentYear = calendar.get(Calendar.YEAR);
    calendar.setTime(refDate);
    calendar.set(Calendar.YEAR, currentYear);
    calendar.add(Calendar.DAY_OF_MONTH, -7);

    Date[] daysOfWeek = new Date[7];
    for (int i = 0; i < 7; i++) {
        daysOfWeek[i] = calendar.getTime();
        calendar.add(Calendar.DAY_OF_MONTH, 1);
    }
    return daysOfWeek;
}

它会像纸一样打印

Sun Jul 29 00:00:00 IST 2018
Mon Jul 30 00:00:00 IST 2018
Tue Jul 31 00:00:00 IST 2018
Wed Aug 01 00:00:00 IST 2018
Thu Aug 02 00:00:00 IST 2018
Fri Aug 03 00:00:00 IST 2018
Sat Aug 04 00:00:00 IST 2018