Fluter setState（）使循环始终被调用

Question

我有一个这样的代码，简单的流程是我从一个对象列表创建一个循环来创建一些小部件。

class ScoringAttribute {
  int _id;
  bool _isdelete;
  double _scorehigh, _scorelow, _scorevalue;
  String _name, _scoretype, _description, _title;
}

class HomePageState extends State<HomePage> with TickerProviderStateMixin {
  List dataScoringAttributes;
  List<ScoringAttribute> listScoringAttributeObjects = new List<ScoringAttribute>();

  final String urlPresentation = ".../.resentations/getPresentations";
  final String urlScoringAttribute = ".../.scoringattributes/getScoringattributes";

  Future<String> getPresentationData() async {
    var responseScoringAttribute = await http.get(
      Uri.encodeFull(urlScoringAttribute),
      headers: {"Accept": "application/json"}
    );

    var scoringAttributeJson = json.decode(responseScoringAttribute.body);

    dataScoringAttributes = scoringAttributeJson['scoringattributes'];

    for(int i = 0; i < dataScoringAttributes.length; i++) {
      var scoringAttributeObject = new ScoringAttribute();

      scoringAttributeObject._id = dataScoringAttributes[i]["id"];
      scoringAttributeObject._description = dataScoringAttributes[i]["iddescription"];
      scoringAttributeObject._isdelete = dataScoringAttributes[i]["isdelete"];
      scoringAttributeObject._name = dataScoringAttributes[i]["name"];
      scoringAttributeObject._scorehigh = double.parse(dataScoringAttributes[i]["scorehigh"].toString());
      scoringAttributeObject._scorelow = double.parse(dataScoringAttributes[i]["scorelow"].toString());
      scoringAttributeObject._scoretype = dataScoringAttributes[i]["scoretype"];
      scoringAttributeObject._title = dataScoringAttributes[i]["title"];
      scoringAttributeObject._scorevalue = double.parse(dataScoringAttributes[i]["scorelow"].toString());

      listScoringAttributeObjects.add(scoringAttributeObject);
    }

    return "Success";
  }

  List<Widget> scoringAttributeList() {
    List<Widget> list = new List();
    for(int i = 0; i < listScoringAttributeObjects.length; i++) {
      if(listScoringAttributeObjects[i]._scoretype == "slider") {
        list.add(
          new Container(
            child: new Column(
              children: <Widget>[
                new Column(
                  children: <Widget>[
                    //THE SLIDER VALUE TEXT
                    new Text(
                      //CONVERT DOUBLE TYPE TO STRING WITHOUT DECIMAL POINTS
                      listScoringAttributeObjects[i]._scorevalue.toStringAsFixed(listScoringAttributeObjects[i]._scorevalue.truncateToDouble() == listScoringAttributeObjects[i]._scorevalue ? 0 : 0),
                      style: new TextStyle(
                        fontSize: 28.0,
                      ),
                    ),
                    //THE SLIDER
                    new Slider(
                      activeColor: Colors.blueAccent,
                      inactiveColor: const Color(0xFFb7d2e0),
                      min: double.parse(listScoringAttributeObjects[i]._scorelow.toString()),
                      max: double.parse(listScoringAttributeObjects[i]._scorehigh.toString()),
                      value: double.parse(listScoringAttributeObjects[i]._scorevalue.toString()),
                      onChanged: (double value) {
                        setState(() {
                          listScoringAttributeObjects[i]._scorevalue = double.parse(value.round().toString());
                        });
                      },
                    ),
                  ],
                ),
              ],
            ),
          ),
        );
      }
      else if(listScoringAttributeObjects[i]._scoretype == "text_field") {
        list.add(...);
      }
      else if(listScoringAttributeObjects[i]._scoretype == "stars") {
        list.add(...);
      }
      else if(listScoringAttributeObjects[i]._scoretype == "thumb") {
        list.add(new Container(...);
      }
    }

    return list;
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body: FutureBuilder<String> (
        future: getPresentationData(),
        builder: (context, snapshot) {
          if(snapshot.hasData) {
            return new Column(
              children: <Widget>[
                new Column(
                  children: scoringAttributeList(),
                ),
              ],
            ),
          }
        },
      ),
    );
  }
}

有一些不同的小部件取决于类型，有4种类型，1种类型可能有超过1个小部件，所以我使循环依赖于来自DB的iIgot数据。

问题是我不知道为什么每次我在循环中使用setState()时，它总是再次处理循环，所以它将是一个无限循环来创建一个新的小部件，它将从头开始复制小部件（仅发生）当调用setState（）时。

例如：列表中有4个数据，如果调用setState()，它将显示8个数据（显示前4个数据两次）

这是我如何将setState（）放入List中的数据的示例

onChanged: (double value) {
    setState(() {
      listScoringAttributeObjects[i]._scorevalue = double.parse(value.round().toString());
    });
},

我认为问题是因为我将qazxsw poi放入List中的一些数据中。因此，当List状态更改时，它将重新呈现与List相关的任何内容。

这是真的吗？

如果是，是否有任何其他解决方案如何更改我的代码？如果不是，我的代码或我的逻辑中是否有任何错误？

谢谢。真的很期待这个解决方案，因为我真的陷入了这个，它已经是一周了:(

Answer 1

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