- 我正在从 API 中提取测验数据，并使用 StreamBuilder
- 使用 PageView.builder 在单独的页面中显示每个问题和选项
- RadioListTile 用于选项并使用地图从列表中迭代答案
问题是--> 每当我在任何问题中选择任何选项时，问题都会自动更改，但索引不会，并且我无法在任何问题上选择任何选项。
我希望我能够很好地解释我的问题。
附加 JSON、PageView.Builder 代码。
页面视图控制器
PageController _pageViewController = PageController(initialPage: 0);
var currentPageIndex;
getCurrectPageIndex(index) {
setState(() {
currentPageIndex = index;
});
}
页面视图按钮
pageViewButtons(context, questionDataIndex, snapshotData, _pageViewController) {
bool isLastQues = questionDataIndex == snapshotData.last;
return Row(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: [
circularButton(
text: "Previous",
onPressed: () {
_pageViewController.previousPage(
duration: Duration(microseconds: 100), curve: Curves.ease);
},
color: brandBlue,
),
circularButton(
text: isLastQues ? "Finish" : "Next",
onPressed: (isLastQues)
? () {
showDialogBox(
context: context,
headingText: "Submit all answers?",
contentText:
"Press Submit to submit answers or Dismiss to cancel",
widget: ElevatedButton(
child: Text("Submit"),
onPressed: questionDataIndex == snapshotData.last
? () => Get.off(() => ResultView())
: null,
),
);
}
: () => _pageViewController.nextPage(
duration: Duration(microseconds: 100), curve: Curves.ease),
color: brandRed,
),
],
);
}
ElevatedButton circularButton(
{String? text, Function()? onPressed, Color? color}) {
return ElevatedButton(
child: Text(text!),
onPressed: onPressed,
style: ButtonStyle(
backgroundColor: MaterialStateProperty.all<Color>(color!),
shape: MaterialStateProperty.all<OutlinedBorder?>(
RoundedRectangleBorder(
borderRadius: BorderRadius.circular(20),
),
),
),
);
}
分页码
_pagination(List<Response> snapshotData) {
return new Container(
width: deviceSize.width * 0.90,
height: deviceSize.height * 0.10,
child: GridView.builder(
itemCount: snapshotData.length,
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 5,
childAspectRatio: 5 / 2,
mainAxisSpacing: 10,
),
itemBuilder: (context, index) {
final indexValue = index;
final indexValuePlus1 = (index + 1).toString();
bool isEqual = indexValue == currentPageIndex;
return Container(
decoration: BoxDecoration(shape: BoxShape.circle),
margin: EdgeInsets.symmetric(horizontal: 5),
child: Material(
shape: CircleBorder(),
clipBehavior: Clip.hardEdge,
color: Colors.white,
child: InkWell(
child: CircleAvatar(
backgroundColor: () {
if (isEqual) {
return brandRed;
} else {
return brandBlue;
}
}(),
child: Padding(
padding: const EdgeInsets.all(2.0),
child: CircleAvatar(
child: Text(
indexValuePlus1,
style: TextStyle(color: Colors.black87, height: 1.2),
),
backgroundColor: Colors.white,
),
),
),
onTap: () {
_pageViewController.jumpToPage(indexValue);
},
),
),
);
},
),
);}
PageView.Builder
_pageView(List<Response> snapshotData, ThemeData themeContext) {
return PageView.builder(
controller: _pageViewController,
physics: NeverScrollableScrollPhysics(),
itemCount: snapshotData.length,
onPageChanged: getCurrectPageIndex,
itemBuilder: (context, index) {
questionDataIndex = snapshotData[index];
final questionTitle = questionDataIndex.title;
final questionAnswers = questionDataIndex.answer;
return Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
_pagination(snapshotData),
SizedBox(height: 20),
Expanded(
child: Stack(
alignment: AlignmentDirectional.topCenter,
clipBehavior: Clip.none,
children: [
Padding(
padding: kDefaultPadding,
child: Wrap(
children: [
Text(questionTitle.inCaps,
style: themeContext.textTheme.headline6!
.copyWith(fontWeight: FontWeight.bold)),
SizedBox(width: 20, height: 20),
...questionAnswers.map((answer) {
return RadioListTile(
key: new Key(answer.id.toString()),
dense: true,
title: Text(
answer.answerText.inCaps,
style: themeContext.textTheme.bodyText2,
),
value: answer.id,
groupValue: groupValue,
onChanged: (value) {
setState(() {
// groupValue = answer.id;
value = groupValue;
});
},
);
}).toList(),
],
),
)
],
),
),
],
);
},
);}
和 JSON
{
"status": "success",
"response": [
{
"question_type": "Multiple Choice",
"difficulty": "Fundamental",
"id": 20,
"title": "node.next -> node.next.next; will make",
"answer": [
{
"id": 26,
"answer_text": "node.next inaccessible"
},
{
"id": 27,
"answer_text": "node.next.next inaccessible"
},
{
"id": 28,
"answer_text": "this node inaccessible"
},
{
"id": 29,
"answer_text": "none of the above!"
}
]
},
{
"question_type": "Multiple Choice",
"difficulty": "Fundamental",
"id": 15,
"title": "For a binary search algorithm to work, it is necessary that the array (list) must be",
"answer": [
{
"id": 8,
"answer_text": "sorted"
},
{
"id": 9,
"answer_text": "Unsorted"
},
{
"id": 10,
"answer_text": "In a heap"
},
{
"id": 11,
"answer_text": "popped out of stack"
}
]
},
{
"question_type": "Multiple Choice",
"difficulty": "Fundamental",
"id": 22,
"title": "A pivot element to partition unsorted list is used in",
"answer": [
{
"id": 34,
"answer_text": "Merge Sort"
},
{
"id": 35,
"answer_text": "Quick Sort"
},
{
"id": 36,
"answer_text": "Insertion Sort"
},
{
"id": 37,
"answer_text": "Selection Sort"
}
]
},
{
"question_type": "Multiple Choice",
"difficulty": "Fundamental",
"id": 17,
"title": "Find the odd out",
"answer": [
{
"id": 14,
"answer_text": "Prim's Minimal Spanning Tree Algorithm"
},
{
"id": 15,
"answer_text": "Kruskal's Minimal Spanning Tree Algorithm"
},
{
"id": 16,
"answer_text": "Floyd-Warshall's All pair shortest path Algorithm"
},
{
"id": 17,
"answer_text": "Dijkstra's Minimal Spanning Tree Algorithm"
}
]
},
{
"question_type": "Multiple Choice",
"difficulty": "Fundamental",
"id": 23,
"title": "Apriori analysis of an algorithm assumes that −",
"answer": [
{
"id": 38,
"answer_text": "the algorithm has been tested before in real environment."
},
{
"id": 39,
"answer_text": "all other factors like CPU speed are constant and have no effect on implementation."
},
{
"id": 40,
"answer_text": "the algorithm needs not to be practical."
},
{
"id": 41,
"answer_text": "none of the above."
}
]
},
{
"question_type": "Multiple Choice",
"difficulty": "Fundamental",
"id": 16,
"title": "Postfix expression is just a reverse of prefix expression.",
"answer": [
{
"id": 12,
"answer_text": "Yes"
},
{
"id": 13,
"answer_text": "No"
}
]
},
{
"question_type": "Multiple Choice",
"difficulty": "Fundamental",
"id": 18,
"title": "If the array is already sorted, which of these algorithms will exhibit the best performance",
"answer": [
{
"id": 18,
"answer_text": "Merge Sort"
},
{
"id": 19,
"answer_text": "Insertion Sort"
},
{
"id": 20,
"answer_text": "Quick Sort"
},
{
"id": 21,
"answer_text": "Heap Sort"
}
]
},
{
"question_type": "Multiple Choice",
"difficulty": "Fundamental",
"id": 21,
"title": "Which of the following algorithm cannot be desiged without recursion −",
"answer": [
{
"id": 30,
"answer_text": "Tower of Hanoi"
},
{
"id": 31,
"answer_text": "Fibonacci Series"
},
{
"id": 32,
"answer_text": "Tree Traversal"
},
{
"id": 33,
"answer_text": "None of the above"
}
]
},
{
"question_type": "Multiple Choice",
"difficulty": "Fundamental",
"id": 19,
"title": "Apriory algorithm analysis does not include −",
"answer": [
{
"id": 22,
"answer_text": "It is the easiest possible way."
},
{
"id": 23,
"answer_text": "To make sure that it is still complete binary tree."
},
{
"id": 24,
"answer_text": "Because left and right subtree might be missing."
},
{
"id": 25,
"answer_text": "None of the above!"
}
]
}
]}
