当我将它存储在 List<Widget> 中时，RadioListTile 指示器没有显示，但它有值并在 flutter 中更改值（我通过打印知道）

Question

所以我正在制作一个测验应用程序，它将随机播放它的无线电选项。我将 radioListTile 存储在列表（小部件）中并使其随机播放。但是我的 radioListTile 不能改变它的指标，但它有值和改变的值（我通过打印知道）

如果我不将它与 List(Widget) 一起存储，它就可以正常工作。当我将它存储在 List(Widget)

中时不正常

这是我的代码：

import 'package:flutter/material.dart';

enum ListJawaban{
  answer1,
  answer2,
  answer3,
  answer4,
  answer5
}

class QuizTemplate extends StatefulWidget {
  const QuizTemplate({
    Key? key,
    required this.question,
    required this.option1,
    required this.option2,
    required this.option3,
    required this.option4,
    required this.option5,
    required this.qNumber
  }) : super(key: key);

  final String question;
  final String option1;
  final String option2;
  final String option3;
  final String option4;
  final String option5;
  final int qNumber;

  @override
  State<QuizTemplate> createState() => _QuizTemplateState();
}

class _QuizTemplateState extends State<QuizTemplate> {

  ListJawaban? _value = null;

  Widget radioListTile({required String text, required ListJawaban jawaban}){
    return RadioListTile<ListJawaban>(
      title: Text("$text"),
      value: jawaban,
      groupValue: _value,
      onChanged: (ListJawaban? newValue){
        setState(() {
          print("jawaban : $newValue");
          print("group value : $_value");
          _value = newValue;
        });
      },
    );
  }

  List<Widget> listRadioOption(){
    return [
      //this should be shuffeled 1 time after build (in init state)
      radioListTile(text: widget.option1, jawaban: ListJawaban.answer1),
      radioListTile(text: widget.option2, jawaban: ListJawaban.answer2),
      radioListTile(text: widget.option3, jawaban: ListJawaban.answer3),
      radioListTile(text: widget.option4, jawaban: ListJawaban.answer4),
      radioListTile(text: widget.option5, jawaban: ListJawaban.answer5),
    ];
  }

  late List<Widget> list2; //list for checking my second tot..

  List<Widget> option(){
    return list2;
  }

  @override
  void initState() {
    super.initState();
    print("---- INIT STATE ----");
    // listRadioOption().shuffle(); //this doesn't shuffle the option, but radio option works perfectly
    list2 = listRadioOption(); //this work if i use this as children,
    list2.shuffle(); //but it won't changing radio option value when user click in it (i dont know why)
  }

  @override
  Widget build(BuildContext context) {
    print("---- BUILD ----");
    return Container(
      child: Column(
        children: [
          Text("${widget.qNumber}. ${widget.question}",style: TextStyle(
            fontSize: 20,
          ),),
          Builder(
            //i actually didn't need this builder, but i used it just for checking variables
            builder: (context){
              print("---- BUILDER ----");
              print("VALUE : $_value");
              return Column(
                children: option(),
              );
            },
          )
        ],
      ),
    );
  }
}

Answer 1

如果您只需要在第一次加载时洗牌一次，请使用级联符号 (..) 运算符 return 洗牌列表。

Note: this list should be loaded as an initial and avoid rebuild this on setState.

List<Widget> listRadioOption(){
    return [
      radioListTile(text: widget.option1, jawaban: ListJawaban.answer1),
      radioListTile(text: widget.option2, jawaban: ListJawaban.answer2),
      radioListTile(text: widget.option3, jawaban: ListJawaban.answer3),
      radioListTile(text: widget.option4, jawaban: ListJawaban.answer4),
      radioListTile(text: widget.option5, jawaban: ListJawaban.answer5),
    ]..shuffle(); // <- This return shuffled list.
  }

当我将它存储在 List<Widget> 中时，RadioListTile 指示器没有显示，但它有值并在 flutter 中更改值（我通过打印知道）

RadioListTile indicator is not showing when i store it in List<Widget> but it have values and change values ( i know it via print) in flutter

indicator

radio-button

dart

flutter