import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(body: Center(child: PopupMenuExample())),
    );
  }
}

class PopupMenuExample extends StatefulWidget {
  const PopupMenuExample({super.key});

  @override
  State<StatefulWidget> createState() => PopupMenuExampleState();
}

class PopupMenuExampleState extends State<PopupMenuExample> {
  String selectedString = "OMG";
  final possibleSelections = ["OMG", "LOL", "ROFL", "WOW"];
  @override
  Widget build(BuildContext context) {
    return Container(
      child: PopupMenuButton<String>(
        key: ValueKey<String>('layerDropdown'),
        initialValue: selectedString,
        onSelected: (selection) {
          setState(() => selectedString = selection);
        },
        itemBuilder: (context) => [
          for (final stringVal in possibleSelections)
            CheckedPopupMenuItem(
              value: stringVal,
              checked: stringVal == selectedString,
              child: Text(stringVal),
            ),
        ],
      ),
    );
  }
}