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[英]I am trying to make a quiz app in flutter with geeks for geeks tutorial as reference.. i have following errors
[英]I am trying to Make a Quiz app for training in Flutter and Dart, and would appreciate assistance in getting the following error cleared
我在 Quiz.dart 和 Main.dart 中遇到两个错误。
在 main.dart 我在answerQuestion: _answerQuestion上遇到错误,
错误:[无法将参数类型“void Function(int)”分配给参数类型“void Function()”。]
主.dart
import 'package:flutter/material.dart';
import './quiz.dart';
import './result.dart';
void main() => runApp(MyApp());
class MyApp extends StatefulWidget {
@override
State<StatefulWidget> createState() {
return _MyAppState();
}
}
class _MyAppState extends State<MyApp> {
static const _questions = const [
{
'questionText': 'What\'s your favorite Color?',
'answers': [
{'text': 'Red', 'score': 10},
{'text': 'White', 'score': 5},
{'text': 'Black', 'score': 3},
{'text': 'Green', 'score': 1},
],
},
{
'questionText': 'What\'s your favorite animal?',
'answers': [
{'text': 'Dog', 'score': 10},
{'text': 'Cat', 'score': 7},
{'text': 'Monkey', 'score': 5},
{'text': 'Tiger', 'score': 2},
],
},
{
'questionText': 'What\'s your favorite Number',
'answers': [
{'text': 'Raman', 'score': 10},
{'text': 'Krishnan', 'score': 7},
{'text': 'Balan', 'score': 5},
{'text': 'Gopi', 'score': 2},
],
},
];
var _questionIndex = 0;
var _totalScore = 0;
void _answerQuestion(int score) {
_totalScore += score;
setState(() {
_questionIndex = _questionIndex + 1;
});
}
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: Text('My First App'),
),
body: _questionIndex < _questions.length
? Quiz(
answerQuestion: _answerQuestion,
questionIndex: _questionIndex,
questions: _questions,
)
: Result(_totalScore),
));
}
}
在 quiz.dart 我收到answerQuestion(answer['score'])错误,
错误:位置 arguments 太多:预期为 0,但找到了 1。 尝试移除额外的 arguments。
测验.dart
import 'package:flutter/material.dart';
import './answer.dart';
import './question.dart';
class Quiz extends StatelessWidget {
// final List<Map<String, Object>> questions;
final List<Map<String, dynamic>> questions;
final int questionIndex;
final VoidCallback answerQuestion;
Quiz({
required this.questions,
required this.answerQuestion,
required this.questionIndex,
});
@override
Widget build(BuildContext context) {
return Column(
children: [
Question(
questions[questionIndex]['questionText'],
),
// ...(questions[questionIndex]['answers'] as List<String>).map((answer) {
...(questions[questionIndex]['answers'] as List<Map<String, dynamic>>)
.map((answer) {
return Answer(() => answerQuestion(answer['score']), answer['text']);
}).toList()
],
);
}
}
我已尽力了解该错误,非常感谢您的帮助,在此先感谢。
void _answerQuestion
function 需要一个int
参数值,但 class Quiz
声明了final VoidCallback answerQuestion
并且VoidCallback
类型的函数不需要任何类型的参数。
这就是为什么您收到参数类型“void Function(int)”无法分配给参数类型“void Function()”错误消息的原因。 您可以使用typedef
关键字定义自己的类型,也可以使用ValueSetter
基金会的 ValueSetter 代替VoidCallback
。
typedef MyOwnFunction = void Function(int score);
class Quiz extends StatelessWidget {
//...
final MyOwnFunction answerQuestion;
//...
}
或者只是在Quiz
class VoidCallback answerQuestion
替换为ValueSetter<int> answerQuestion
answerQuestion。
VoidCallback
是一个void Function()
原型,但您将void Function(int)
传递给answerQuestion
。 例如,使用ValueSetter<int>
。
关于第二个错误检查如何将参数传递给Answer
构造函数。 我认为您已经命名了参数(它们用弯括号括起来),但是您将它们作为位置传递。
我有同样的问题,但我更正了。 您应该更改final VoidCallback answerQuestion;
作为final Function answerQuestion;
有用
有同样的问题,只需更改:
final VoidCallback answerQuestion;
至final Function answerQuestion;
它对我来说就像一个魅力
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