Question

我当前在Android中使用DatePicker来允许用户选择日期。是否有可能只允许用户选择星期一，而禁用所有其他日期进行选择？我没有在文档中找到任何内容。

当前我正在使用它来显示DatePicker：

DatePickerDialog datePickerDialog = new DatePickerDialog(AddAppointment.this,
        new DatePickerDialog.OnDateSetListener() {

            @Override
            public void onDateSet(DatePicker view, int year,
                                  int monthOfYear, int dayOfMonth) {

            // Do stuff with the info
            }
        }, setYear, setMonth, setDay);
datePickerDialog.show();

Answer 1

您可以使用此库Material Date Time Picker，在这里您可以设置显示特定日期的选项，例如：

datePicker.setSelectableDays(Calendar[] days)

然后将Calendar数组作为包含所有可选日期的参数传递。

要查找星期一数组，可以使用以下逻辑：-Get all Fridays in a date Range in Java

Answer 2

您可以使用以下方法之一计算所选日期的日历周或计算最近的星期一。他们被评论了，所以我只写简短的文字。

public class ExampleDateCalculation {

    public static void main(String[] args) {
        int dayOfMonth = 4;
        int monthOfYear = 3;
        int year = 2018;

        // create a java.time.LocalDate of the given integers
        LocalDate localDate = LocalDate.of(year, monthOfYear, dayOfMonth);

        // calculate the calendar week of it
        int calendarWeekTheLocalDateIsIn = getCalendarWeek(localDate);

        // calculate the last Monday before this date
        LocalDate lastMonday = getLastFrom(DayOfWeek.MONDAY, localDate);

        // create a formatter for your locale
        DateTimeFormatter germanDateFormatter = DateTimeFormatter.ofPattern("dd.MM.yyyy");

        System.out.println(localDate.format(germanDateFormatter)
                + " is in calendar week "
                + calendarWeekTheLocalDateIsIn
                + " of the system locale and the last Monday before was at "
                + lastMonday.format(germanDateFormatter));
    }

    /**
     * <p>
     * Gets the calendar week number of the given {@link LocalDate} based on the
     * {@link Locale} of the operating system.
     * </p>
     * 
     * @param localDate the date of the day
     * @return the calendar week number the day is in
     */
    public static int getCalendarWeek(LocalDate localDate) {
        WeekFields weekFields = WeekFields.of(Locale.getDefault());
        return localDate.get(weekFields.weekOfWeekBasedYear());
    }

    /**
     * <p>
     * Gets the date of the last given weekday or day of week starting from the
     * weekday of the given date. The method calculates the date of the nearest
     * weekday chronologically backwards.
     * </p>
     * <p>
     * <strong>For example:</strong><br>
     * If the weekday of the given date is a Monday and the given day of week is a
     * Tuesday, then this method will return the date of the Tuesday before today,
     * which is 6 days back in the past.
     * </p>
     * 
     * @param weekday the day of week whose date is to be determined
     * @param from    the date to start from calculating backwards
     * @return the date of the last given day of week starting from the given date
     */
    public static LocalDate getLastFrom(DayOfWeek weekday, LocalDate from) {
        DayOfWeek fromWeekday = from.getDayOfWeek();
        int fromWeekdayValue = fromWeekday.getValue();
        int weekdaysValue = weekday.getValue();
        int daysToSubtract = 0;

        /*
         * Calculate the days to go back and be beware of negative values by means of
         * case differentiation. Get the positive difference by subtracting the smaller
         * value from the larger one and subtract a week if the result would be 0.
         */
        if (fromWeekdayValue < weekdaysValue) {
            daysToSubtract = 7 - (weekdaysValue - fromWeekdayValue);
        } else if (fromWeekdayValue > weekdaysValue) {
            daysToSubtract = fromWeekdayValue - weekdaysValue;
        } else {
            daysToSubtract = 7;
        }

        return from.minusDays(daysToSubtract);
    }
}

如果您只希望用户看到日历周或星期一，请按照Uday Nayak的答案中的建议进行操作。

如果有人发现此代码有错误或知道此代码的缺点，请告诉我。

Answer 3

您可以尝试做一些不同的操作。首先，更改用户不想选择的日期的字体颜色（星期一除外），然后过滤选定的活动日期并禁用功能，直到选择星期一为止。

DatePicker：仅选择星期一

3 个答案: