flutter - 如何在最后使用 TimeofDay 获得 AM 或 Pm，如果它为空，我如何在其上添加一些文本？

Question

我想在时间结束时添加 AM 或 PM，为此我尝试过像 DateFormat('hh:mm a') 这样添加 AM 或 PM，但它选择了错误的时间。如何解决这个问题？请帮助我：-

Future selectTimeEnd() async {
final TimeOfDay picked = await showTimePicker(
  context: context,
  initialTime: selectedTime,
  builder: (BuildContext context, Widget child){
    return Theme(
      data: ThemeData.dark(),
      child: child,
    );
  });
if (picked != null)
  setState(() {
    selectedTime = picked;
    _hour = selectedTime.hour.toString();
    _minute = selectedTime.minute.toString();
    _time = _hour + ' : ' + _minute;
    _timeControllerEnd.text = _time;  ///this _time displays the selected time.

    var inputDate = DateTime(selectedTime.hour,selectedTime.minute);
    var outputFormat = DateFormat('hh:mm a'); ///but this shows wrong selected time 
    var outputDate = outputFormat.format(inputDate);
    print(outputDate);

  });

}

如果选择的时间为空，那么提交的文本仍然为空，但我想在那个地方有一些文本提示，为此我已经尝试过：-

 String _dropTime = _timeControllerEnd.text != null ? _timeControllerEnd.text : "Until";
    child: Align(
         alignment: Alignment.centerLeft,
         child: Text(_dropTime != null ? _dropTime : "Until",textAlign: TextAlign.start,
         style: TextStyle(fontSize: 20)),
      ),

Answer 1

更改此代码

child: Text(_dropTime != null ? _dropTime : "Until",textAlign: TextAlign.start,
         style: TextStyle(fontSize: 20)),

对此

chid: _dropTime!=null?Text(_dropTime):Text("untill"),