创建了简单条形图，但它不会显示在页面上。
这是我的密码

import 'package:flutter/material.dart';
import 'bar_chart_sample1.dart';

class BarChartPage extends StatelessWidget {
  const BarChartPage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      color: Color.fromARGB(255, 166, 166, 166),
      child: ListView(
        children: <Widget>[
          Padding(
            padding: EdgeInsets.only(
              left: 28,
              right: 28,
            ),
            child: BarChartWidget(),
          ),
          SizedBox(height: 22),
        ],
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_charts/charts.dart';

class BarChartWidget extends StatefulWidget {
  const BarChartWidget({Key? key}) : super(key: key);

  @override
  State<BarChartWidget> createState() => _BarChartWidgetState();
}

class _BarChartWidgetState extends State<BarChartWidget> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        body: Center(
            child: Container(
      child:
          SfCartesianChart(primaryXAxis: CategoryAxis(), series: <ChartSeries>[
        // Initialize line series
        LineSeries<ChartData, String>(
            dataSource: [
              // Bind data source
              ChartData('Jan', 35),
              ChartData('Feb', 28),
              ChartData('Mar', 34),
              ChartData('Apr', 32),
              ChartData('May', 40)
            ],
            xValueMapper: (ChartData data, _) => data.x,
            yValueMapper: (ChartData data, _) => data.y)
      ]),
    )));
  }
}

class ChartData {
  ChartData(this.x, this.y);
  final String x;
  final double? y;
}

它应该看起来像这样

我做错了什么？
我做错了什么？我做错了什么？我做错了什么？我做错了什么？我做错了什么？我做错了什么？我做错了什么？我做错了什么？