Flutter Generic StatefulWidget Example

main.dart

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);
  static const String _title = 'Stateful Generic Example';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: _title),
    );
  }
}

class GenericWidget<T> extends StatefulWidget {
  const GenericWidget({Key? key}) : super(key: key);

  @override
  State<GenericWidget> createState() => _GenericWidgetState<T>();
}

class _GenericWidgetState<T> extends State<GenericWidget<T>> {
  @override
  Widget build(BuildContext context) {
    return Text('type: ${T.toString()}');
  }
}

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

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: const <Widget>[
            GenericWidget<String>(),
            GenericWidget<int>(),
            GenericWidget<bool>(),
            GenericWidget<Object>(),
            GenericWidget<List<String>>(),
          ],
        ),
      ),
    );
  }
}