ChatGPT(AI)でコード生成！flutterの簡単なToDoアプリを作ってみよう。

import 'package:flutter/material.dart';

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

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

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

class Todo {
  String text;
  bool isDone;
  Todo({required this.text, this.isDone = false});
}

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

  @override
  State<TodoPage> createState() => _TodoPageState();
}

class _TodoPageState extends State<TodoPage> {
  final List<Todo> _todos = [];
  final TextEditingController _controller = TextEditingController();

  void _addTodo() {
    final text = _controller.text.trim();
    if (text.isEmpty) return;
    setState(() {
      _todos.add(Todo(text: text));
      _controller.clear();
      _sortTodos();
    });
  }

  void _toggleDone(int index) {
    setState(() {
      _todos[index].isDone = !_todos[index].isDone;
      _sortTodos();
    });
  }

  void _deleteTodo(int index) {
    setState(() {
      _todos.removeAt(index);
    });
  }

  void _sortTodos() {
    // 未完了(false)が先、完了(true)が後になるようにソート
    _todos.sort((a, b) {
      if (a.isDone == b.isDone) return 0;
      return a.isDone ? 1 : -1;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text("ToDo Sample")),
      body: Column(
        children: [
          Expanded(
            child: ListView.builder(
              itemCount: _todos.length,
              itemBuilder: (context, index) {
                final todo = _todos[index];
                return Card(
                  margin: const EdgeInsets.symmetric(
                    horizontal: 12,
                    vertical: 6,
                  ),
                  child: ListTile(
                    title: Text(
                      todo.text,
                      style: TextStyle(
                        fontSize: 18,
                        decoration: todo.isDone
                            ? TextDecoration.lineThrough
                            : TextDecoration.none,
                      ),
                    ),
                    trailing: Row(
                      mainAxisSize: MainAxisSize.min,
                      children: [
                        IconButton(
                          icon: Icon(
                            todo.isDone
                                ? Icons.check_box
                                : Icons.check_box_outline_blank,
                            color: Colors.green,
                          ),
                          onPressed: () => _toggleDone(index),
                        ),
                        IconButton(
                          icon: const Icon(Icons.delete, color: Colors.red),
                          onPressed: () => _deleteTodo(index),
                        ),
                      ],
                    ),
                  ),
                );
              },
            ),
          ),
          Container(
            padding: const EdgeInsets.all(8.0),
            color: Colors.grey.shade200,
            child: Row(
              children: [
                Expanded(
                  child: TextField(
                    controller: _controller,
                    decoration: const InputDecoration(
                      hintText: "新しいToDoを入力",
                      border: OutlineInputBorder(),
                    ),
                    onSubmitted: (_) => _addTodo(),
                  ),
                ),
                const SizedBox(width: 8),
                ElevatedButton(onPressed: _addTodo, child: const Text("追加")),
              ],
            ),
          ),
        ],
      ),
    );
  }
}