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小时或接下来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,我得到以下异常:

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.永远不会显示DatePickerDialog.

如果我注释掉该setMaxDate()行,那么它可以正常工作.在这种情况下,最小日期得到尊重.

如果我将其更改为setMaxDate(nowMilliseconds),我仍然会得到NullPointerException.

Answer 1

一直在研究这个问题.这是Android中的一个错误.只需关闭日历视图,你就可以了:

picker.setCalendarViewShown(false);

Answer 2

尝试更换：

setDatePickerDialogRange(dialog);
dialog.show();

到：

dialog.show();
someView.post(new Runnable() {
  public void run() {
    setDatePickerDialogRange(dialog);
  }
});

（someViewsome 在哪里View，如果Handler有的话则为 a ）

这会将调用延迟到setDatePickerDialogRange()渲染对话框之后，并且可能是解决您的问题的方法。