The getter 'hourOfPeriod' was called on null. Receiver: null Tried calling: hourOfPeriod in flutter

Question

I am trying to add TimePicker in my todo app. But whenever I navigate to the screen where I have added timepicker I get error saying this.

The getter 'hourOfPeriod' was called on null. Receiver: null Tried calling: hourOfPeriod

I have no idea how to fix this or where it is coming from.

These are my code

        class _CreateTaskScreenState extends State<CreateTaskScreen> {
          final TextEditingController _taskTitleController = TextEditingController();

          String taskTitle = '';
          bool _taskTitleValidate = false;
          DateTime _currentDate = new DateTime.now();

          TimeOfDay _currentTime = new TimeOfDay.now();
          TimeOfDay selectedTime;

          @override
          Widget build(BuildContext context) {
            /// Time Picker
            MaterialLocalizations localizations = MaterialLocalizations.of(context);
            String formattedTime = localizations.formatTimeOfDay(selectedTime,
                alwaysUse24HourFormat: false);
            String timeText = formattedTime;

return Scaffold(
      backgroundColor: Color(kPrimaryColor),
      appBar: AppBar(
        elevation: 0.0,
        title: Text('Create a Task'),
      ),
      body: SafeArea(

          child: Container(

            child: Column(
              children: <Widget>[


                TimePicker(
                  icon: Icons.access_time,
                  selectedTime: '$timeText',
                  onPress: () async {
                    selectedTime = await showTimePicker(
                      context: context,
                      initialTime: _currentTime,
                    );

                  },
                ),

Anyone, please help me to solve this.

Answer 1

In the first build of the Screen your selectedTime Object is null. Then you want to create a formatted String with it. Which wont work on a null object.

TimeOfDay selectedTime;


String formattedTime = localizations.formatTimeOfDay(selectedTime,
                alwaysUse24HourFormat: false);

EDIT:

class _CreateTaskScreenState extends State<CreateTaskScreen> {
  final TextEditingController _taskTitleController = TextEditingController();
   MaterialLocalizations localizations;

  String taskTitle = '';
  bool _taskTitleValidate = false;
  DateTime _currentDate = new DateTime.now();
  TimeOfDay _currentTime = new TimeOfDay.now();

  String timeText = 'initText'; // 
@override
void didChangeDependencies() {
 super.didChangeDependencies(); 
 setState{(){
  timeText = localizations.formatTimeOfDay(_currentTime,
                            alwaysUse24HourFormat: false);
  });

}


  @override
  Widget build(BuildContext context) {
    /// Time Picker
    localizations = MaterialLocalizations.of(context);

    return Scaffold(
      backgroundColor: Colors.red,
      appBar: AppBar(
        elevation: 0.0,
        title: Text('Create a Task'),
      ),
      body: SafeArea(
        child: Container(
          child: Column(
            children: <Widget>[
              TimePicker(
                icon: Icons.access_time,
                selectedTime: '$timeText',
                onPress: () {
                  showTimePicker(
                    context: context,
                    initialTime: _currentTime,
                  ).then(
                    (TimeOfDay value) => setState(
                      () {
                        timeText = localizations.formatTimeOfDay(value,
                            alwaysUse24HourFormat: false);
                      },
                    ),
                  );
                },
              )
            ],
          ),
        ),
      ),
    );
  }
}

Answer 2

As said above you're passing slectedTime to formatTimeOfDay function before initialising it first.