var name = 'Bob'; // 类型推断为 String
String city = 'New York'; // 明确指定类型为 String
int age = 30; // 明确指定类型为 int
double price = 19.99; // 明确指定类型为 double
bool isActive = true; // 明确指定类型为 bool

// 声明一个 List
List<String> fruits = ['apple', 'banana', 'orange'];

// 声明一个 Set
Set<int> uniqueNumbers = {1, 2, 3, 1}; // 实际存储为 {1, 2, 3}

// 声明一个 Map
Map<String, String> capitals = {
  'USA': 'Washington D.C.',
  'Japan': 'Tokyo'
};

final String message = 'Hello'; // 运行时常量
const double PI = 3.14159; // 编译时常量

// const 也可以用于构造函数，创建编译时常量对象
const Point origin = Point(0, 0);

import 'package:flutter/material.dart';

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

  @override
  State<RegisterForm> createState() => _RegisterFormState();
}

class _RegisterFormState extends State<RegisterForm> {
  // 使用 late 关键字延迟初始化，或者在声明时赋初始值
  late String _name; // 存储用户姓名，String 类型
  late int _age; // 存储用户年龄，int 类型
  late String _email; // 存储用户邮箱，String 类型
  late String _password; // 存储用户密码，String 类型
  bool _agreeToTerms = false; // 存储用户是否同意条款，bool 类型

  final TextEditingController _nameController = TextEditingController();
  final TextEditingController _ageController = TextEditingController();
  final TextEditingController _emailController = TextEditingController();
  final TextEditingController _passwordController = TextEditingController();

  @override
  void dispose() {
    _nameController.dispose();
    _ageController.dispose();
    _emailController.dispose();
    _passwordController.dispose();
    super.dispose();
  }

  void _submitForm() {
    setState(() {
      _name = _nameController.text;
      _age = int.tryParse(_ageController.text) ?? 0; // 尝试解析为 int，失败则为 0
      _email = _emailController.text;
      _password = _passwordController.text;
    });

    // 打印收集到的数据
    print('Name: $_name');
    print('Age: $_age');
    print('Email: $_email');
    print('Password: $_password');
    print('Agree to terms: $_agreeToTerms');

    // 可以在这里进行数据验证或发送到后端
    if (_agreeToTerms) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('注册成功！')),
      );
    } else {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('请同意用户条款！')),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('用户注册'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          children: <Widget>[
            TextField(
              controller: _nameController,
              decoration: const InputDecoration(labelText: '姓名'),
              keyboardType: TextInputType.name,
            ),
            TextField(
              controller: _ageController,
              decoration: const InputDecoration(labelText: '年龄'),
              keyboardType: TextInputType.number,
            ),
            TextField(
              controller: _emailController,
              decoration: const InputDecoration(labelText: '邮箱'),
              keyboardType: TextInputType.emailAddress,
            ),
            TextField(
              controller: _passwordController,
              decoration: const InputDecoration(labelText: '密码'),
              obscureText: true,
            ),
            Row(
              children: <Widget>[
                Checkbox(
                  value: _agreeToTerms,
                  onChanged: (bool? newValue) {
                    setState(() {
                      _agreeToTerms = newValue ?? false;
                    });
                  },
                ),
                const Text('我同意用户条款'),
              ],
            ),
            ElevatedButton(
              onPressed: _submitForm,
              child: const Text('注册'),
            ),
          ],
        ),
      ),
    );
  }
}

void main() {
  runApp(const MaterialApp(home: RegisterForm()));
}