用于日期选择器的java Android IllegalArgumentException

Question

我用于活动的日期选择器在KitKat上崩溃，但在其他所有更新的操作系统上都能工作。这是我在旧设备上遇到的例外：

java.lang.IllegalArgumentException: fromDate: Mon Apr 10 07:59:25 EDT 2017 does not precede toDate: Mon Apr 10 07:59:25 EDT 2017

代码块堆栈跟踪指向：

private void showDatePicker(){
   DatePickerDialog datePickerDialog = new DatePickerDialog(
   getActivity(), this, calendar.get(Calendar.YEAR),  calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH));
   //this is where the crash happens
   datePickerDialog.getDatePicker().setMinDate(new Date().getTime());
   datePickerDialog.show();
}

请让我知道关于这个问题的信息是否足够。有办法吗

Answer 1

要解决此问题，请在DatePickerDialog实例化之前为minDate创建一个时间戳：

private void showDatePicker(){
   long now = System.currentTimeMillis();
   DatePickerDialog datePickerDialog = new DatePickerDialog(
      getActivity(), this, calendar.get(Calendar.YEAR),  calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH));
   datePickerDialog.getDatePicker().setMinDate(now);
   datePickerDialog.show();
}

---

此崩溃是由于API21之前版本的CalendarView和API21的calendarViewMode == MODE_HOLO中的错误造成的

尽管setMinDate包含一个用注释突出显示的更正：

public void setMinDate(long minDate) {
    ...
    mMinDate.setTimeInMillis(minDate);
    // make sure the current date is not earlier than
    // the new min date since the latter is used for
    // calculating the indices in the adapter thus
    // avoiding out of bounds error
    Calendar date = mAdapter.mSelectedDate;
    if (date.before(mMinDate)) {
        mAdapter.setSelectedDay(mMinDate);
    }
    // reinitialize the adapter since its range depends on min date
    mAdapter.init();

签入setSelectedDay只比较mMinDate和mSelectedDate的日期准确性：

public void setSelectedDay(Calendar selectedDay) {
    if (selectedDay.get(Calendar.DAY_OF_YEAR) == mSelectedDate.get(Calendar.DAY_OF_YEAR)
            && selectedDay.get(Calendar.YEAR) == mSelectedDate.get(Calendar.YEAR)) {
        return;
    }

mSelectedDate和mMinDate是指向同一天的点，因此mSelectedDate将保持不变（即处于错误状态mSelectedDate < mMinDate）

然后控制流将运行到mAdapter.init，然后进入getWeeksSinceMinDate。在该函数中，mMinDate和mSelectedDate的比较将以毫秒的精度进行：

private int getWeeksSinceMinDate(Calendar date) {
    if (date.before(mMinDate)) {
        throw new IllegalArgumentException("fromDate: " + mMinDate.getTime()
                + " does not precede toDate: " + date.getTime());
    }

由于mSelectedDate在mMinDate之前的几毫秒内初始化，崩溃将发生

在一个较新的实现中，这段代码被重写，因此API21+缺少这个问题

Answer 2

我通过延迟解决了这个问题：

private void showDatePicker(){
   DatePickerDialog datePickerDialog = new DatePickerDialog(
   getActivity(), this, calendar.get(Calendar.YEAR),  calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH));
   //this is where the crash happens
   datePickerDialog.getDatePicker().setMinDate(new Date().getTime() - 10000);
   datePickerDialog.show();

}