flutter - 为什么在使用第二个文本字段之前显示cubit结果？

Question

这个应用程序的目标是从第一个文本字段中获取输入，然后在第二个屏幕中对其进行打乱。然后提示用户解读并将其输入到第二个文本字段中。如果用户的 second_text_field 输入与 firs_text_field 中的输入匹配，则 UI 应显示“OKAY”；否则，“不好”。在我看来，变量 mycontroller 在到达 BlockBuilder 下的文本小部件时什么都不存储。这是快照：

这是相关的屏幕代码：

      import 'package:flutter/material.dart';
  import 'package:flutter_bloc/flutter_bloc.dart';

  import 'package:rafia_unscramble_demo/cubit/sentence_cubit.dart';

  class ScrambledUnscrambled extends StatelessWidget {
  final String? userInputFromFirstTextField;
  //final String? secondSTring;

  ScrambledUnscrambled({
  required this.userInputFromFirstTextField,
  //this.secondSTring,
  });

  @override
  Widget build(BuildContext context) {
  String str = "";
  final mycontroller = TextEditingController();

  List<String> inputs = userInputFromFirstTextField!.split(" ");
  String shuffledWords(List<String> input) {
    input.shuffle();
    // print(input);
    return input.join(" ");
  }

  return BlocProvider<SentenceCubit>(
    create: (context) => SentenceCubit(),
    child: Scaffold(
      appBar: AppBar(
        title: const Text('Unscramble'),
      ),
      body: Column(
        children: [
          Card(
            margin: const EdgeInsets.only(top: 50),
            child: Container(
              alignment: Alignment.center,
              width: double.infinity,
              height: 100,
              color: Colors.blueAccent,
              padding: const EdgeInsets.all(15),
              child: Text(
                shuffledWords(inputs),
                style: const TextStyle(
                  fontSize: 20,
                  fontWeight: FontWeight.bold,
                  color: Colors.white,
                ),
              ),
            ),
          ),
          const SizedBox(
            width: 20,
          ),
          Container(
            padding: const EdgeInsets.all(20),
            alignment: Alignment.center,
            child: TextField(
              controller: mycontroller,
              onChanged: (String text) {},
              decoration: InputDecoration(
                border: OutlineInputBorder(
                  borderRadius: BorderRadius.circular(10),
                ),
                hintText: 'Please, enter a grammatically correct sentence.',
                labelText: 'Second Input',
                labelStyle: TextStyle(
                  fontSize: 24,
                  color: Colors.blue[900],
                ),
              ),
            ),
          ),
          ElevatedButton(
            onPressed: () {
              str = mycontroller.text;
            },
            child: const Text("Submit"),
          ),
          if (str == mycontroller.text)
            BlocBuilder<SentenceCubit, SentenceState>(
              builder: (context, state) {
                return Container(
                  color: Colors.blueAccent,
                  padding: const EdgeInsets.all(20),
                  width: double.infinity,
                  height: 100,
                  child: Text(
                    BlocProvider.of<SentenceCubit>(context).checkForError(
                      str,
                      userInputFromFirstTextField!,
                    ),
                  ),
                );
              },
            ),
        ],
      ),
    ),
  );
  }
  }

这是肘部分： SentenceState：

    part of 'sentence_cubit.dart';

@immutable
abstract class SentenceState {}

class SentenceInitial extends SentenceState {
  final String textInput;
  SentenceInitial({
    this.textInput = "",
  });
}

class Success extends SentenceState {
  final String okay;
  Success({
    required this.okay,
  });
}

class Failed extends SentenceState {
  final String notOkay;
  Failed({
    required this.notOkay,
  });
}

句子肘：

    import 'package:bloc/bloc.dart';
import 'package:flutter/material.dart';
import 'package:meta/meta.dart';

part 'sentence_state.dart';

class SentenceCubit extends Cubit<SentenceState> {
  //final String firstScreenText;
  // final String secondString;
  SentenceCubit(
      // this.firstScreenText,
      //this.secondString,
      )
      : super(SentenceInitial());

  String checkForError(String getSecondText, String getFirstString) {
    // getSecondText = secondString;
    final okay = Success(okay: "Okay");
    final notOkay = Failed(notOkay: "Not Okay");

    if (getSecondText == getFirstString) {
      return okay.okay;
    } else if (getSecondText == " ") {
      return " ";
    } else {
      return notOkay.notOkay;
    }
  }
}

Answer 1

} else if (getSecondText == " ") {

仅当第二个文本是空格时，这才是正确的，我猜这是导致您的错误的错字。