DropDown Menu

import 'package:flutter/material.dart';

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

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

class _ShowDropDownMenuState extends State<ShowDropDownMenu> {

  final menuItems = ['Apple', 'Pear', 'Grape', 'Orange'];
  String? _dropdownValue;

  @override
  void initState() {
    // Initialize the menu with the first item
    // The selection key (value) is the index as a String
    _dropdownValue = "0";

    super.initState();
  }

  @override
  Widget build(BuildContext context) {


    return Scaffold(
      appBar: AppBar(title: const Text("Dropdown Menu")),
      body: Container(
        padding: const EdgeInsets.all(20),
        alignment: Alignment.center,
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            const Text("Please select an item"),
            const SizedBox(height: 50),
            dropDownMenu(context)
          ],
        )
      ),
    );
  }

  /// **********************************************************************
  /// Displays the DropDown menu
  /// **********************************************************************
  Widget dropDownMenu(BuildContext context) {
    return DropdownButton<String>(
        elevation: 16,
        items: createListOfItems(),
        value: _dropdownValue,
        onChanged: (String? newValue) {
          setState(() {
            // newValue is the value of the selected item
            _dropdownValue = newValue ?? "";
            print("Selected item = $_dropdownValue");

          });

        },
        );
  }
  
  /// **********************************************************************
  /// Build the list of items from the menuItems list
  /// **********************************************************************
  List<DropdownMenuItem<String>> createListOfItems() {
    final items = List<DropdownMenuItem<String>>.generate(
        menuItems.length,
        (index) => DropdownMenuItem(
            value: "$index",
            child: Text(menuItems[index])));
    return items;
  }

}