Switch demo

switch_demo.dart

import 'package:flutter/material.dart';

void main() => runApp(const SwitchApp());

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
          useMaterial3: true, colorSchemeSeed: const Color(0xff6750a4)),
      home: Scaffold(
        appBar: AppBar(title: const Text('Switch Sample')),
        body: const Center(
          child: SwitchExample(),
        ),
      ),
    );
  }
}

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

  @override
  State<SwitchExample> createState() => _SwitchExampleState();
}

class _SwitchExampleState extends State<SwitchExample> {
  bool light0 = true;
  bool light1 = true;
  bool light2 = true;

  final MaterialStateProperty<Icon?> thumbIcon =
      MaterialStateProperty.resolveWith<Icon?>(
    (Set<MaterialState> states) {
      // Thumb icon when the switch is selected.
      if (states.contains(MaterialState.selected)) {
        return const Icon(Icons.check);
      }
      return const Icon(Icons.close);
    },
  );

  @override
  Widget build(BuildContext context) {
    return Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: <Widget>[
        Switch(
          value: light0,
          onChanged: (bool value) {
            setState(() {
              light0 = value;
            });
          },
        ),
        Switch(
          thumbIcon: thumbIcon,
          value: light1,
          onChanged: (bool value) {
            setState(() {
              light1 = value;
            });
          },
        ),
      ],
    );
  }
}