Flutter - DropDownButton Widget

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter DropDownButton',
      theme: ThemeData(primarySwatch: Colors.green),
      home: const MyHomePage(),
      debugShowCheckedModeBanner: false,
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key}) : super(key: key);

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

class _MyHomePageState extends State<MyHomePage> {
  // Initial Selected Value
  String dropdownvalue = 'Item 1';

  // List of items in our dropdown menu
  var items = [
      'Item 1',
      'Item 2',
      'Item 3',
      'Item 4',
      'Item 5'
  ];
  
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("GFG DropDownButton"),
        backgroundColor: Colors.green,
        foregroundColor: Colors.white,
      ),
      body: Center(
        child: DropdownButton(
          // Initial Value
          value: dropdownvalue,

          // Down Arrow Icon
          icon: const Icon(Icons.keyboard_arrow_down),

          // Array list of items
          items:
              items.map((String items) {
                return DropdownMenuItem(value: items, child: Text(items));
              }).toList(),
          // After selecting the desired option,it will
          // change button value to selected value
          onChanged: (String? newValue) {
            setState(() {
              dropdownvalue = newValue!;
            });
          },
        ),
      ),
    );
  }
}