How To Add Dropdown Form Field Using Flutter Android

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter Demo',
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);


  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  String dropdownValue= 'A';
  @override
  Widget build(BuildContext context) {
    var currentSelectedValue;
    const deviceTypes = ["Mac", "Windows", "Mobile"];
    return Scaffold(
      appBar: AppBar(
        centerTitle: true,
        backgroundColor: Colors.pink,
        title: Text('DropDown TextField'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(15.0),
        child:  Container(
          height: 60,
          child:  Container(
            padding: EdgeInsets.symmetric(horizontal: 3),
            child: FormField<String>(
              builder: (FormFieldState<String> state) {
                return InputDecorator(
                  decoration: InputDecoration(
                      border: OutlineInputBorder(
                          borderRadius: BorderRadius.circular(5.0))),
                  child: DropdownButtonHideUnderline(
                    child: DropdownButton<String>(
                      hint: Text("Dropdown"),
                      value: currentSelectedValue,
                      isDense: true,
                      onChanged: (newValue) {
                        setState(() {
                          currentSelectedValue = newValue;
                        });
                        print(currentSelectedValue);
                      },
                      items: deviceTypes.map((String value) {
                        return DropdownMenuItem<String>(
                          value: value,
                          child: Text(value),
                        );
                      }).toList(),
                    ),
                  ),
                );
              },
            ),
          ),
        ),
      ),
    );
  }
}