错误:没有为类'MyApp‘定义getter 'WordPair’。在阅读flutter文档中的“编写您的第一个应用程序”指南时

class MyApp extends StatelessWidget {
  // 定义WordPair为一个简单的字符串对
  final String wordPair;

  // 构造函数
  MyApp({required this.wordPair});

  // 定义WordPair的getter
  String get WordPair => wordPair;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Word Pair App'),
        ),
        body: Center(
          child: Text(WordPair), // 使用getter获取WordPair的值
        ),
      ),
    );
  }
}

void main() {
  runApp(MyApp(wordPair: 'Hello World')); // 传递WordPair的值
}

class MyApp extends StatelessWidget {
  final String firstWord;
  final String secondWord;

  MyApp({required this.firstWord, required this.secondWord});

  String get WordPair => '$firstWord $secondWord'; // 计算getter

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Word Pair App'),
        ),
        body: Center(
          child: Text(WordPair),
        ),
      ),
    );
  }
}