在颤动中删除TextFormField中的错误信息

import 'package:flutter/material.dart';

class MyForm extends StatefulWidget {
  @override
  _MyFormState createState() => _MyFormState();
}

class _MyFormState extends State<MyForm> {
  final GlobalKey<FormState> _formKey = GlobalKey<FormState>();
  bool _showError = false;

  String _validateInput(String value) {
    if (value.isEmpty) {
      return '请输入内容';
    }
    return null;
  }

  void _submitForm() {
    if (_formKey.currentState.validate()) {
      // 表单验证通过，执行提交操作
    } else {
      setState(() {
        _showError = true;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Form(
      key: _formKey,
      child: Column(
        children: [
          TextFormField(
            validator: _validateInput,
            decoration: InputDecoration(
              labelText: '输入框',
              errorText: _showError ? '请输入内容' : null,
            ),
            onChanged: (value) {
              setState(() {
                _showError = false;
              });
            },
          ),
          RaisedButton(
            onPressed: _submitForm,
            child: Text('提交'),
          ),
        ],
      ),
    );
  }
}