flutter - Flutter:如何通过ToggleButtons对ListView进行排序

Question

我有一个列表 View ，如下所示:



列表 View 的代码:

_listCountry(index) {
  Country country = _country[index];
  return Row(
    mainAxisAlignment: MainAxisAlignment.spaceEvenly,
    children: <Widget> [
      Text('${country.id}'),
      Text(country.name),
      Text('${country.population}'),
    ],
  );
}

我创建了排序方法，效果很好:

_onSortID() {
  setState(() {
    _country.sort((a, b) => b.id.compareTo(a.id));
  });
}

_onSortName() {
  setState(() {
    _country.sort((a, b) => b.name.compareTo(a.name));
  });
}

_onSortPopulation() {
  setState(() {
    _country.sort((b, a) => b.population.compareTo(a.population));
  });
}

那么，如何将这些方法放入Onpressed的ToggleButtons中，以便在按下时可以进行排序？ 这是“切换按钮”代码:

ToggleButtons(
  children: <Widget> [
    Text('Country ID'),
    Text('Country Name'),
    Text('Country Population')
  ],
  onPressed: (int index) {
    setState(() {
      for (int buttonIndex = 0; buttonIndex < isSelected.length; buttonIndex++) {
        if (buttonIndex == index) {
          isSelected[buttonIndex] = !isSelected[buttonIndex];
        } else {
          isSelected[buttonIndex] = false;
        }
      }
    });
  },
  isSelected: isSelected,
)

Answer 1

试试这个 :

定义方法列表

List sortMethods;

然后像这样在 initState()中创建它:

@override
  initState() {
    sortMethods = List.of({
      () => setState(
            () {
              _country.sort((a, b) => b.id.compareTo(a.id));
            },
          ),
      () => setState(() {
            _country.sort((a, b) => b.name.compareTo(a.name));
          }),
      () => setState(() {
            _country.sort((a, b) => b.population.compareTo(a.population));
          })
    });
    super.initState();
  }

当您选择 切换按钮，称这样的方法:

 onPressed: (int index) {
   for (int buttonIndex = 0; buttonIndex < isSelected.length; buttonIndex++) {
        if (buttonIndex == index) {
          isSelected[buttonIndex] = !isSelected[buttonIndex];
        } else {
          isSelected[buttonIndex] = false;
        }
         sortMethods[index]();
      }
     }