flutter/examples/api/lib/material/expansion_tile/expansion_tile.0.dart

// 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 [ExpansionTile].

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(
      title: _title,
      home: Scaffold(
        appBar: AppBar(title: const Text(_title)),
        body: const MyStatefulWidget(),
      ),
    );
  }
}

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

  @override
  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  bool _customTileExpanded = false;

  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        const ExpansionTile(
          title: Text('ExpansionTile 1'),
          subtitle: Text('Trailing expansion arrow icon'),
          children: <Widget>[
            ListTile(title: Text('This is tile number 1')),
          ],
        ),
        ExpansionTile(
          title: const Text('ExpansionTile 2'),
          subtitle: const Text('Custom expansion arrow icon'),
          trailing: Icon(
            _customTileExpanded
                ? Icons.arrow_drop_down_circle
                : Icons.arrow_drop_down,
          ),
          children: const <Widget>[
            ListTile(title: Text('This is tile number 2')),
          ],
          onExpansionChanged: (bool expanded) {
            setState(() => _customTileExpanded = expanded);
          },
        ),
        const ExpansionTile(
          title: Text('ExpansionTile 3'),
          subtitle: Text('Leading expansion arrow icon'),
          controlAffinity: ListTileControlAffinity.leading,
          children: <Widget>[
            ListTile(title: Text('This is tile number 3')),
          ],
        ),
      ],
    );
  }
}