效果圖：

date.jpg

time.jpg

import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import 'dart:async';

class DatePickerDemo extends StatefulWidget {
  DatePickerDemo({Key key}) : super(key: key);

  _DatePickerDemoState createState() => _DatePickerDemoState();
}

class _DatePickerDemoState extends State<DatePickerDemo> {
  DateTime _selectDate = DateTime.now();
  TimeOfDay _selectTime = TimeOfDay.now();

  //選擇日期的方法
  _selectDateMethod () async {
    debugPrint('選擇時間方法');
   final DateTime date = await showDatePicker(
      context: context,
      initialDate: _selectDate,
      firstDate: DateTime(1998),
      lastDate: DateTime(2029),
    );

    if(date == null) return;

    setState(() {
      _selectDate = date;
    });

  }

  //Future表示異步的返回值  必須使用async
  Future <void> _selectTimeMethod () async {
    debugPrint('選擇時間方法');
   final TimeOfDay timeOfDay = await showTimePicker(
      context: context,
      initialTime: _selectTime,
    );

    if(timeOfDay == null) return;

    setState(() {
      _selectTime = timeOfDay;
    });

  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('DatePicker'),
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          InkWell(
            splashColor: Colors.green,
            onTap: (){
              _selectDateMethod();
            },
            child: Row(
              mainAxisAlignment: MainAxisAlignment.center,
              
              children: <Widget>[
                Text('日期選擇'),
                Text(DateFormat().add_yMd().format(_selectDate)), 
                Icon(Icons.arrow_drop_down)
                
                ],
            ),
          ),

           InkWell(
            splashColor: Colors.green,
            onTap: (){
              _selectTimeMethod();
            },
            child: Row(
              mainAxisAlignment: MainAxisAlignment.center,
              
              children: <Widget>[
                Text('時間選擇'),
                Text(_selectTime.format(context)), 
                Icon(Icons.arrow_drop_down)
                
                ],
            ),
          )
        ],
      ),
    );
  }
}