Navigate to another Page and showing Quizcards with multiple answers - flutter

Question

I just want to pass the Featured Topics to another class, but that doesn't work. It is suggested to me to perform a zero check, but then the next ERROR comes. Also I need some help to properly display the quiz card with the answers
import 'package:flutter/material.dart';
import 'QuizScreen.item.dart';
class QuizCard {
String question;
List<String> answers;
int correctAnswerIndex;
QuizCard(
{required this.question,
required this.answers,
required this.correctAnswerIndex});
}
//------------------------------------------------------------------------------
class QuizTopic {
String topic;
List<QuizCard> quizCards;
QuizTopic({required this.topic, required this.quizCards});
}
//------------------------------------------------------------------------------
// ignore: must_be_immutable
class SchriftlFragenBW extends StatefulWidget {
const SchriftlFragenBW({super.key});
#override
State<SchriftlFragenBW> createState() => _SchriftlFragenBWState();
}
class _SchriftlFragenBWState extends State<SchriftlFragenBW> {
bool allSelected = false;
String number = '';
final List<String> _themes = [
'Theme 1',
'Theme 2',
'Theme 3',
'Theme 4',
'Theme 5',
'Theme 6',
'Theme 7',
'Theme 8',
];
final List<bool> _selected = List.filled(8, false);
final Map<String, List<QuizCard>> _quizCards = {
'Theme 1': [
QuizCard(
question: 'Question 1',
answers: ['Answer 1.1', 'Answer 1.2', 'Answer 1.3'],
correctAnswerIndex: 2),
QuizCard(
question: 'Question 1.1',
answers: ['Answer 1.1.1', 'Answer 1.1.2', 'Answer 1.1.3'],
correctAnswerIndex: 2),
],
'Theme 2': [
QuizCard(
question: 'Question 2',
answers: ['Answer 2.1', 'Answer 2.2', 'Answer 2.3'],
correctAnswerIndex: 1),
QuizCard(
question: 'Question 2.2',
answers: ['Answer 2.2.1', 'Answer 2.2.2', 'Answer 2.2.3'],
correctAnswerIndex: 1),
],
// Add more quiz cards for each theme
};
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.grey[900],
body: ListView(
children: <Widget>[
for (int i = 0; i < _themes.length; i++)
CheckboxListTile(
value: _selected[i],
onChanged: (bool? value) {
setState(() {
_selected[i] = value ?? false;
});
},
title: Text(
_themes[i],
style: const TextStyle(color: Colors.white),
),
),
const SizedBox(
height: 8,
),
Row(
children: [
Expanded(
child: Padding(
padding: const EdgeInsets.fromLTRB(20, 10, 10, 0),
child: Container(
decoration: BoxDecoration(
border: Border.all(
width: 1.0,
color: Colors.grey[850]!,
style: BorderStyle.solid)),
child: TextButton(
child: Text(
allSelected ? 'unselect all' : 'select all',
style: const TextStyle(color: Colors.white),
),
onPressed: () {
allSelected = !allSelected;
for (int i = 0; i < _selected.length; i++) {
_selected[i] = allSelected;
}
setState(() {});
}),
),
),
),
Expanded(
child: Padding(
padding: const EdgeInsets.fromLTRB(0, 10, 20, 0),
child: Container(
decoration: BoxDecoration(
border: Border.all(
width: 1.0,
color: Colors.grey[850]!,
style: BorderStyle.solid)),
child: TextButton(
child: const Text(
'learning',
style: TextStyle(color: Colors.white),
),
onPressed: () {
bool atLeastOneSelected = false;
for (int i = 0; i < _selected.length; i++) {
if (_selected[i]) {
atLeastOneSelected = true;
break;
}
}
if (atLeastOneSelected) {
List<QuizCard> quizCards = [];
for (int i = 0; i < _selected.length; i++) {
if (_selected[i]) {
quizCards.addAll(_quizCards[_themes[i]]!,
);
}
}
if (quizCards.isNotEmpty) {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) =>
QuizPage(quizCards: quizCards),
),
);
}
}
}),
),
),
),
],
),
],
),
);
}
}
//------------------------------------------------------------------------------
class QuizPage extends StatefulWidget {
final List<QuizCard> quizCards;
const QuizPage({super.key, required this.quizCards});
#override
// ignore: library_private_types_in_public_api
_QuizPageState createState() => _QuizPageState();
}
class _QuizPageState extends State<QuizPage> {
int currentQuizCardIndex = 0;
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: const Text('Quiz')),
body: Column(
children: <Widget>[
Padding(
padding: const EdgeInsets.all(16.0),
child: Text(
widget.quizCards[currentQuizCardIndex].question,
style: const TextStyle(fontSize: 18.0),
),
),
Expanded(
child: ListView.builder(
itemCount: widget.quizCards[currentQuizCardIndex].answers.length,
itemBuilder: (context, index) {
return ListTile(
title: Text(
widget.quizCards[currentQuizCardIndex].answers[index]),
onTap: () {
setState(() {
currentQuizCardIndex =
(currentQuizCardIndex + 1) % widget.quizCards.length;
});
},
);
},
),
),
],
),
);
}
}
I asked chatGPT, because why not, but it only gets me answers that where not very useful. I changed the code from displaying flipcharts to display quizcards with multiple answers, but now I got that ERROR and dont know why...