来自时间选择器的 Flutter Format Time of Day答案

【问题标题】：Flutter Format Time of Day from time picker来自时间选择器的 Flutter Format Time of Day
【发布时间】：2019-09-25 21:59:07
【问题描述】：

我正在尝试从我的颤振应用程序中的时间选择器中格式化所选时间。我不知道为什么，但事实证明这比它应该的更困难。我试图达到的最终结果是小时：小步舞曲或下午 5:00。在用户从时间选择器小部件中选择时间后，这将显示在一个盒子容器中。我有一个名为 'timeFormater()' 的方法，它将格式化选择的时间，但是当我运行我的代码。格式化TimeOfDay（）是否有更简单的方法/方法？

我的代码：

      import 'package:flutter/material.dart';
    import 'package:flutter/cupertino.dart';
    import 'package:intl/intl.dart';
    import 'package:auto_size_text/auto_size_text.dart';
    import 'dart:io' show Platform;

    class DateTimePicker extends StatefulWidget {
      @override
      _DateTimePickerState createState() => _DateTimePickerState();
    }

    class _DateTimePickerState extends State<DateTimePicker> {
      DateTime _date = new DateTime.now();
      TimeOfDay _time = new TimeOfDay.now();
      Duration initialtimer = new Duration();
      DateTime _datePicked;
      TimeOfDay _timePicked;


      @override
      void initState() {
       // timeController.addListener(_time);

      }

      @override
      Widget build(BuildContext context) {
        return Container(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
            children: <Widget>[
              Row(
                mainAxisAlignment: MainAxisAlignment.start,
                // mainAxisSize: MainAxisSize.min,
                children: <Widget>[
                  dateContainer(),
                  timeContainer()
                ],
              ),
              Row(
                mainAxisAlignment: MainAxisAlignment.start,
                children: <Widget>[
                  customDatePicker(context),
                  customTimePicker(context)
                ],
              ),
            ],
          ),
        );
      }
 Widget customTimePicker(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.only(left: 12.0),
      child: FlatButton(
          child: Text('Time', style: TextStyle(
              color: Colors.white
          ),),
          color: Colors.deepOrange,
          onPressed: () => _selectedTime(context)
      ),
    );
  }
 Future<Null> _selectedTime(BuildContext context) async {
    _timePicked = await showTimePicker(
        context: context,
        initialTime: _time);

    if (_timePicked != null) {
      setState(() {
        _time = _timePicked;
      });
    }
  }
 Widget timeContainer() {
    return Container(
      width: 100,
      height: 100,
      child: Padding(
          padding: const EdgeInsets.only(left: 16.0, top: 16.0,bottom: 16.0),
          child: Container(
            decoration: BoxDecoration(
              border: Border.all(
                width: .5,
                color: Colors.black
              )
            ),
            child: timeFormater(),
          )
      ),
    );
  }

  Widget timeFormater() {
    return Column(
      children: <Widget>[
        SizedBox(
          height: 20.0,
        ),
        _timePicked != null
            ? TimeOfDay(hour: _timePicked.hour, minute: _timePicked.minute)
            : SizedBox(
          width: 0.0,
          height: 0.0,
        ),
      ],
    );
  }
}

错误信息：

flutter: ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
flutter: The following assertion was thrown building DateTimePicker(dirty, dependencies: [_InheritedTheme,
flutter: _LocalizationsScope-[GlobalKey#6c45d]], state: _DateTimePickerState#7eeb8):
flutter: type 'TimeOfDay' is not a subtype of type 'Widget'
flutter:
flutter: Either the assertion indicates an error in the framework itself, or we should provide substantially
flutter: more information in this error message to help you determine and fix the underlying cause.
flutter: In either case, please report this assertion by filing a bug on GitHub:
flutter:   https://github.com/flutter/flutter/issues/new?template=BUG.md
flutter:
flutter: When the exception was thrown, this was the stack:
flutter: #0      _DateTimePickerState.timeFormater (package:rallie_app/utils/custom_date_timer.dart:176:13)
flutter: #1      _DateTimePickerState.timeContainer (package:rallie_app/utils/custom_date_timer.dart:163:20)
flutter: #2      _DateTimePickerState.build (package:rallie_app/utils/custom_date_timer.dart:37:15)
flutter: #3      StatefulElement.build (package:flutter/src/widgets/framework.dart:3830:27)
flutter: #4      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3741:15)
flutter: #5      Element.rebuild (package:flutter/src/widgets/framework.dart:3564:5)
flutter: #6      BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2277:33)
flutter: #7      _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:700:20)
flutter: #8      _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:275:5)
flutter: #9      _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
flutter: #10     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
flutter: #11     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:842:5)
flutter: #15     _invoke (dart:ui/hooks.dart:209:10)
flutter: #16     _drawFrame (dart:ui/hooks.dart:168:3)
flutter: (elided 3 frames from package dart:async)

【问题讨论】：

TimeOfDay 不是 Widget 像 Text、Container、SizedBox 等 - 你必须从你的 timeFormater() 方法返回一个 Widget
有没有办法格式化 TimeOfDay 以显示小时：分钟？即使我将它添加到文本小部件中，如果我无法正确显示它仍然无法解决我的问题
如果你想格式化TimeOfDay使用format()方法
您能否添加更多说明，例如有效的代码示例。我尝试使用 TimeOfDayFormat.H_colon_mn 方法，但它没有格式化从时间选择器中选择的时间

标签： flutter widget timeofday

【解决方案1】：

从日期选择器中选择日期。

DateTime pickedDate;

@override
void initState() {
super.initState();
pickedDate = DateTime.now();
currentTime = "${pickedDate}";
time = TimeOfDay.now();
}

Container(
   width: width/2.3,
   child: InkWell(
   onTap: () {
   _pickDate();
   },
   child: IgnorePointer(
   child: AppTextField(
   text: "${pickedDate.day}/${pickedDate.month}/${pickedDate.year}",
   suffixIcon: Icon(Icons.calendar_today),
   onTextChnage: null,
   ),
   ),
   ),
   ),

选择日期的方法

 _pickDate() async{
DateTime date = await showDatePicker(
    context: context,
    initialDate: pickedDate,
    firstDate: DateTime(DateTime.now().year-10),
    lastDate: DateTime(DateTime.now().year+10)
);
debugPrint("${pickedDate} ${time}");
//debugPrint(date as String);
if(date != null){
  setState(() {
    pickedDate = date;
  });
}}

【讨论】：

【解决方案2】：

这将为您正确格式化 TimeOfDay：

final localizations = MaterialLocalizations.of(context);
final formattedTimeOfDay = localizations.formatTimeOfDay(timeOfDay);

【讨论】：

这似乎是获取字符串输出的正确方法。这应该是一个公认的答案。
这是一个不错的解决方案，但依赖于上下文，不适合在不可用的地方使用。
@funder7 如果您使用像 GetX 这样的 StateManagement，您可以简单地在包装上述代码的字符串返回类型方法中使用 Get.context。
@Akradhi 我不知道 GetX 抱歉。我的意思是，如果解决方案依赖于 context，那么它在 context 不可用的情况下将无法使用。这只是需要考虑的事情，但不一定是阻止程序！我想说，如果您需要正确格式化TimeOfDay，那么必须要有可用的上下文。但老实说，我已经离开 Flutter 大约 6 个月了，其他人肯定会比我准备得更充分:-)
@funder7 你可以看看这个框架。我提供了下面的链接。 pub.dev/packages/get 这真的很容易实现，在此之后我们不必太担心上下文。

【解决方案3】：

  String timeValue ='Select Time';
  TimeOfDay selectedTime =TimeOfDay.now();

  Future<Null> _selectTime(BuildContext context) async {
  final TimeOfDay picked_s = await showTimePicker(
    context: context,
    initialTime: selectedTime, builder: (BuildContext context, Widget 
  child) {
       return MediaQuery(
         data: 
       MediaQuery.of(context).copyWith(alwaysUse24HourFormat:false),
        child: child,
      );});

if (picked_s != null && picked_s != selectedTime )
  setState(() {
    selectedTime = picked_s;
    timeValue = picked_s.format(context);   //time convert into string formate
  });}

【讨论】：

【解决方案4】：

字符串时间 = _timePicked.format(context);

【讨论】：

非常简单的解决方案！ +1。只是想知道如何使用此解决方案指定显示格式（上午/下午 12 小时与 24 小时），与来自@bwhite 的解决方案相比。
@Fabrice 试试这个。这专门针对您的情况： import 'package:flutter/material.dart'; String formatTime({BuildContext context, TimeOfDay timeOfDay, bool alwaysUse24HourFormat = false}) { final localizations = MaterialLocalizations.of(context);最终 formattedTimeOfDay = 本地化.formatTimeOfDay(timeOfDay, alwaysUse24HourFormat: alwaysUse24HourFormat);返回格式化的TimeOfDay； }

【解决方案5】：

这就是我使用 Date Time 和 TimeOfDay 在 Flutter 平台上同时将它们的值分开的方式。

static DateTime _eventdDate = DateTime.now();

static var now =
  TimeOfDay.fromDateTime(DateTime.parse(_eventdDate.toString()));



 String _eventTime = now.toString().substring(10, 15);



Future _pickTime() async {
TimeOfDay timepick = await showTimePicker(
    context: context, initialTime: new TimeOfDay.now());

if (timepick != null) {
  setState(() {
    _eventTime = timepick.toString().substring(10, 15);
  });
} }

Future _pickDate() async {

DateTime datepick = await showDatePicker(
    context: context,
    initialDate: new DateTime.now(),
    firstDate: new DateTime.now().add(Duration(days: -365)),
    lastDate: new DateTime.now().add(Duration(days: 365)));

if (datepick != null) {
  setState(() {
    _eventdDate = datepick;
  });
} }

【讨论】：

【解决方案6】：

这个问题与 TimeOfDay 无关——您只是尝试将值用作小部件。在你的代码中改变这个

 _timePicked != null
        ? TimeOfDay(hour: _timePicked.hour, minute: _timePicked.minute)

到

_timePicked != null
        ? Text(TimeOfDay(hour: _timePicked.hour, minute: _timePicked.minute)
            .toString())

它会起作用的。

【讨论】：

【解决方案7】：

你可以使用 DatePicker.showTimePicker

    DatePicker.showTimePicker(context,  
            showTitleActions: true,  
                onChanged: (date) {  
                 print('change $date');  
            }, onConfirm: (date) {  
                 print('confirm $date');  
            }, currentTime: DateTime.now(), locale: LocaleType.pt);

【讨论】：