Getx无法正确更新TextFormField列表。

使用Obx代替GetBuilder。

原始代码示例：

class MyWidget extends StatelessWidget {
  final List<String> _items = [];
  final _formKey = GlobalKey<FormState>();
  final _textController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          Form(
            key: _formKey,
            child: TextFormField(
              controller: _textController,
              validator: (value) {
                if (value.isEmpty) {
                  return 'Please enter something';
                } else {
                  return null;
                }
              },
              onFieldSubmitted: (_) => _addItem(),
            ),
          ),
          Expanded(
            child: GetBuilder<MyController>(
              init: MyController(),
              builder: (_) => ListView.builder(
                itemCount: _.items.length,
                itemBuilder: (context, index) {
                  return ListTile(
                    title: Text(_.items[index]),
                  );
                },
              ),
            ),
          ),
        ],
      ),
    );
  }

  void _addItem() {
    if (_formKey.currentState.validate()) {
      Get.find<MyController>().addItem(_textController.text);
      _textController.clear();
    }
  }
}

class MyController extends GetxController {
  RxList<String> _items = RxList();

  List<String> get items => _items;

  void addItem(String item) {
    _items.add(item);
    update();
  }
}

解决方案代码示例：

class MyWidget extends StatelessWidget {
  final List<String> _items = [];
  final _formKey = GlobalKey<FormState>();
  final _textController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          Form(
            key: _formKey,
            child: TextFormField(
              controller: _textController,
              validator: (value) {
                if (value.isEmpty) {
                  return 'Please enter something';
                } else {
                  return null;
                }
              },
              onFieldSubmitted: (_) => _addItem(),
            ),
          ),
          Expanded(
            child: SingleChildScrollView(
              child: Column(
                children: [
                  for (String item
                      in Get.find<MyController>().items.value)
                    TextField(
                      enabled: false,