Flutter ListView 在错误的索引或元素处自动更新

Question

我正在尝试创建一个列表视图来显示某个数字的加法。在图像中，我正在尝试为 ListView 中的 16 个步骤生成加法 table。它在加载时看起来很好，但在滚动顶部和底部元素后会自动更新。这个问题只有在基本控制ListView中item个数的变量tableSize的值超过15时才会出现，请问如何解决这个问题？？

// table大小 = 16 && tCount = 10

这是代码

return ListView.builder(
  key: UniqueKey(),
  padding: EdgeInsets.symmetric(horizontal: 5),
  itemCount: DataFile.tableSize,
  scrollDirection: Axis.vertical,
  itemBuilder: (context, index) {
    tCount = tCount + 1;

    String title;

    print(" Tcount = ${tCount}");

    if (sign == DataFile.divisionSign) {
      double ans = tableNo / tCount;
      title = tableNo.toString() +
          space +
          sign +
          space +
          tCount.toString() +
          space +
          equal +
          space +
          f.format(ans);
    } else {
      int ans;
      if (sign == DataFile.additionSign) {
        ans = tableNo + tCount;
      } else if (sign == DataFile.subtractionSign) {
        ans = tableNo - tCount;
      } else {
        ans = tableNo * tCount;
      }

      title = tableNo.toString() +
          space +
          space +
          sign +
          space +
          space +
          tCount.toString() +
          space +
          space +
          equal +
          space +
          space +
          int.parse(ans.toString()).toString();
      print(title);
    }

    return InkWell(
      child: Container(
        height: cellHeight,
        margin: EdgeInsets.symmetric(
            vertical: ConstantData.getScreenPercentSize(context, 2.3)),
        child: Center(
          child: ConstantWidget.getTextWidget(
              title,
              ConstantData.textColors!,
              ConstantData.getPercentSize(cellHeight, 98),
              FontWeight.w500,
              TextAlign.center),
        ),
      ),
      onTap: () {},
    );
  },
);

Answer 1

需要更改 tCount，它是状态变量中的可变数据。

使用此代码：

return ListView.builder(
  key: UniqueKey(),
  padding: EdgeInsets.symmetric(horizontal: 5),
  itemCount: DataFile.tableSize,
  scrollDirection: Axis.vertical,
  itemBuilder: (context, index) {

tCount = index + 1; //change here 

String title;

print(" Tcount = ${tCount}");

if (sign == DataFile.divisionSign) {
  double ans = tableNo / tCount;
  title = tableNo.toString() +
      space +
      sign +
      space +
      tCount.toString() +
      space +
      equal +
      space +
      f.format(ans);
} else {
  int ans;
  if (sign == DataFile.additionSign) {
    ans = tableNo + tCount;
  } else if (sign == DataFile.subtractionSign) {
    ans = tableNo - tCount;
  } else {
    ans = tableNo * tCount;
  }

  title = tableNo.toString() +
      space +
      space +
      sign +
      space +
      space +
      tCount.toString() +
      space +
      space +
      equal +
      space +
      space +
      int.parse(ans.toString()).toString();
  print(title);
}

return InkWell(
  child: Container(
    height: cellHeight,
    margin: EdgeInsets.symmetric(
        vertical: ConstantData.getScreenPercentSize(context, 2.3)),
    child: Center(
      child: ConstantWidget.getTextWidget(
          title,
          ConstantData.textColors!,
          ConstantData.getPercentSize(cellHeight, 98),
          FontWeight.w500,
          TextAlign.center),
    ),
  ),
  onTap: () {},
);
},
);

Flutter ListView 在错误的索引或元素处自动更新

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