// Copyright 2014 The Flutter Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. // Flutter code sample for M3 Checkbox with error state import 'package:flutter/material.dart'; void main() => runApp(const MyApp()); class MyApp extends StatelessWidget { const MyApp({super.key}); static const String _title = 'Flutter Code Sample'; @override Widget build(BuildContext context) { return MaterialApp( theme: ThemeData(useMaterial3: true, colorSchemeSeed: const Color(0xff6750a4)), title: _title, home: Scaffold( appBar: AppBar(title: const Text(_title)), body: const Center( child: MyStatefulWidget(), ), ), ); } } class MyStatefulWidget extends StatefulWidget { const MyStatefulWidget({super.key}); @override State<MyStatefulWidget> createState() => _MyStatefulWidgetState(); } class _MyStatefulWidgetState extends State<MyStatefulWidget> { bool? isChecked = true; @override Widget build(BuildContext context) { return Column( mainAxisAlignment: MainAxisAlignment.center, children: <Widget>[ Checkbox( tristate: true, value: isChecked, onChanged: (bool? value) { setState(() { isChecked = value; }); }, ), Checkbox( isError: true, tristate: true, value: isChecked, onChanged: (bool? value) { setState(() { isChecked = value; }); }, ), Checkbox( isError: true, tristate: true, value: isChecked, onChanged: null, ), ], ); } }