date_field/example/lib/main.dart

import 'package:flutter/material.dart';
import 'package:date_field/date_field.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        inputDecorationTheme: const InputDecorationTheme(
            border: OutlineInputBorder()
        ),

        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}


class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  DateTime selectedDate;

  @override
  Widget build(BuildContext context) {

    return Scaffold(
        body: Padding(
          padding: const EdgeInsets.all(20.0),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              const FlutterLogo(size: 100),
              const SizedBox(height: 20),
              const Text('DateField package showcase'),
              const Padding(
                padding: EdgeInsets.symmetric(vertical: 20.0),
                child: Text('DateTimeField'),
              ),
              DateTimeField(
                  decoration: const InputDecoration(
                      hintText: 'Please select your birthday date and time'
                  ),
                  selectedDate: selectedDate,
                  onDateSelected: (DateTime value) {
                    setState(() {
                      selectedDate = value;
                    });
                  }
              ),
              const Padding(
                padding: EdgeInsets.symmetric(vertical: 20.0),
                child: Text('DateTimeFormField'),
              ),
              Form(
                child: Column(
                  children: [
                    DateTimeFormField(
                      decoration: const InputDecoration(
                        hintStyle: TextStyle(color: Colors.black45),
                        errorStyle: TextStyle(color: Colors.redAccent),
                        border: OutlineInputBorder(),
                        suffixIcon: Icon(Icons.event_note),
                        labelText: 'My Super Date Time Field',
                      ),
                      autovalidateMode: AutovalidateMode.always,
                      validator: (e) => (e?.day ?? 0) == 1 ? 'Please not the first day' : null,
                      onDateSelected: (DateTime value) {
                        print(value);
                      },
                    ),
                    const SizedBox(height: 50),
                    DateTimeFormField(
                      decoration: const InputDecoration(
                        hintStyle: TextStyle(color: Colors.black45),
                        errorStyle: TextStyle(color: Colors.redAccent),
                        border: OutlineInputBorder(),
                        suffixIcon: Icon(Icons.event_note),
                        labelText: 'Only time',
                      ),
                      mode: DateTimeFieldPickerMode.time,
                      autovalidateMode: AutovalidateMode.always,
                      validator: (e) => (e?.day ?? 0) == 1 ? 'Please not the first day' : null,
                      onDateSelected: (DateTime value) {
                        print(value);
                      },
                    ),
                  ],
                ),
              ),
            ],
          ),
        )
    );
  }
}