android - 在 DatePickerDialog 中使用 DatePicker setMaxDate() 时出现 NullPointerException

Question

我正在使用 DatePickerDialog，我正在尝试设置最小和最大日期，以便用户只能选择前 24 小时或后 24 小时内的日期。

这是代码。 (请注意，如果在 Android 3.0 或更高版本上运行，它只会尝试设置最小/最大范围。)

private void showDatePickerDialog() {
    DatePickerDialog.OnDateSetListener listener = new DatePickerDialog.OnDateSetListener() {
        @Override
        public void onDateSet(DatePicker view, int year, int monthOfYear,
                              int dayOfMonth) {
            calendar.set(Calendar.YEAR, year);
            calendar.set(Calendar.MONTH, monthOfYear);
            calendar.set(Calendar.DAY_OF_MONTH, dayOfMonth);
            onCalendarChanged();
        }
    };

    DatePickerDialog dialog = new DatePickerDialog(this,
                                                   listener,
                                                   calendar.get(Calendar.YEAR),
                                                   calendar.get(Calendar.MONTH),
                                                   calendar.get(Calendar.DAY_OF_MONTH));
    setDatePickerDialogRange(dialog);
    dialog.show();
}

@SuppressLint("NewApi")
private void setDatePickerDialogRange(DatePickerDialog dialog) {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
        DatePicker picker = dialog.getDatePicker();
        long oneDayMilliseconds = 24 * 60 * 60 * 1000;
        long nowMilliseconds = new Date().getTime();
        long minDate = nowMilliseconds - oneDayMilliseconds;
        long maxDate = nowMilliseconds + oneDayMilliseconds;
        picker.setMinDate(minDate);
        picker.setMaxDate(maxDate);
    }
}

这在 2.2 设备上运行时工作正常，但在 4.0.4 设备 (Galaxy Tab 2 7.0) 上，我得到这个异常:

11-14 07:58:08.917: E/AndroidRuntime(16611): FATAL EXCEPTION: main
11-14 07:58:08.917: E/AndroidRuntime(16611): java.lang.NullPointerException
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.CalendarView.onScroll(CalendarView.java:910)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.CalendarView.access$600(CalendarView.java:74)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.CalendarView$2.onScroll(CalendarView.java:771)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.AbsListView.invokeOnItemScrollListener(AbsListView.java:1391)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.ListView.layoutChildren(ListView.java:1705)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.AbsListView.onLayout(AbsListView.java:2040)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.View.layout(View.java:11330)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.ViewGroup.layout(ViewGroup.java:4235)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1644)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1502)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.LinearLayout.onLayout(LinearLayout.java:1415)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.View.layout(View.java:11330)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.ViewGroup.layout(ViewGroup.java:4235)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.FrameLayout.onLayout(FrameLayout.java:431)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.View.layout(View.java:11330)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.ViewGroup.layout(ViewGroup.java:4235)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1644)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.LinearLayout.layoutHorizontal(LinearLayout.java:1633)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.LinearLayout.onLayout(LinearLayout.java:1417)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.View.layout(View.java:11330)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.ViewGroup.layout(ViewGroup.java:4235)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.FrameLayout.onLayout(FrameLayout.java:431)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.View.layout(View.java:11330)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.ViewGroup.layout(ViewGroup.java:4235)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.FrameLayout.onLayout(FrameLayout.java:431)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.View.layout(View.java:11330)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.ViewGroup.layout(ViewGroup.java:4235)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.FrameLayout.onLayout(FrameLayout.java:431)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.View.layout(View.java:11330)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.ViewGroup.layout(ViewGroup.java:4235)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1644)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1502)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.LinearLayout.onLayout(LinearLayout.java:1415)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.View.layout(View.java:11330)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.ViewGroup.layout(ViewGroup.java:4235)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.FrameLayout.onLayout(FrameLayout.java:431)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.View.layout(View.java:11330)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.ViewGroup.layout(ViewGroup.java:4235)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.FrameLayout.onLayout(FrameLayout.java:431)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.View.layout(View.java:11330)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.ViewGroup.layout(ViewGroup.java:4235)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.widget.FrameLayout.onLayout(FrameLayout.java:431)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.View.layout(View.java:11330)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.ViewGroup.layout(ViewGroup.java:4235)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1548)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2505)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.os.Handler.dispatchMessage(Handler.java:99)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.os.Looper.loop(Looper.java:137)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at android.app.ActivityThread.main(ActivityThread.java:4514)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at java.lang.reflect.Method.invokeNative(Native Method)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at java.lang.reflect.Method.invoke(Method.java:511)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
11-14 07:58:08.917: E/AndroidRuntime(16611):    at dalvik.system.NativeStart.main(Native Method)

这会立即发生。 DatePickerDialog 永远不会显示。

如果我注释掉 setMaxDate() 行，那么它工作正常。在这种情况下，将遵守最短日期。

如果我将其更改为 setMaxDate(nowMilliseconds)，我仍然会遇到 NullPointerException。

Answer 1

在这方面工作了很长一段时间。这是 Android 中的错误。只需关闭日历 View 即可:

picker.setCalendarViewShown(false);