arrays - 在 Point Chart Flutter 中实现 List

Question

你能说出这段代码的区别吗:

final installmentList = [];
for (var i = 0; i < installment.length; i++) {
    installmentList.add(new LinearStatistic(i, installment[i].count));
}

来自这段代码:

final data = [
    new LinearStatistic(0, 5),
    new LinearStatistic(1, 25),
    new LinearStatistic(2, 100),
    new LinearStatistic(3, 75),
];

当我调试并使用“data”变量时，返回语句被调用，但当我使用“instalmentList”变量时，它没有被调用。

return [
    new charts.Series<LinearStatistic, int>(
        id: 'Sales',
        colorFn: (_, __) => charts.MaterialPalette.blue.shadeDefault,
        domainFn: (LinearStatistic sales, _) => sales.position,
        measureFn: (LinearStatistic sales, _) => sales.count,
        data: data,
        )
    ];
}

Answer 1

static List<charts.Series<LinearSales, int>> _createSampleData() {
// final data = [
//   new LinearSales(0, 5),
//   new LinearSales(1, 25),
//   new LinearSales(2, 100),
//   new LinearSales(3, 75),
// ];
List installment = [5, 10, 4, 22, 12];
final List installmentList = <LinearSales>[];
for (var i = 0; i < installment.length; i++) {
  installmentList.add(new LinearSales(i, installment[i]));
}
return [
  new charts.Series<LinearSales, int>(
    id: 'Sales',
    colorFn: (_, __) => charts.MaterialPalette.blue.shadeDefault,
    domainFn: (LinearSales sales, _) => sales.year,
    measureFn: (LinearSales sales, _) => sales.sales,
    data: installmentList,
  )
];}

使用此代码作为引用 这是我所做的更改 final List installmentList = <LinearSales>[];