JFreeChart日期轴格式化问题

我有一个时间序列图表。我的 X 轴是日期，Y 轴只是数字。我正在尝试格式化 x 轴上的日期，但是我不断收到异常。我的代码如下：

        TimeSeries trueSeries = new TimeSeries("True Data");
        TimeSeries regressionSeries = new TimeSeries("Regression Line");
        TimeSeries averageSeries = new TimeSeries("Moving Average");

        for (Date date : regression.keySet()) {
            Calendar cal = Calendar.getInstance();
            cal.setTime(date);
            int month = cal.get(Calendar.MONTH) + 1;
            int day = cal.get(Calendar.DAY_OF_MONTH);
            int year = cal.get(Calendar.YEAR);
            regressionSeries.add(new Day(day, month, year),
                    regression.get(date));
            averageSeries.add(new Day(day, month, year),
                    movingAverage.get(date));
            trueSeries.add(new Day(day, month, year), trueData.get(date));
        }
        TimeSeriesCollection dataset = new TimeSeriesCollection();
        dataset.addSeries(trueSeries);
        dataset.addSeries(regressionSeries);
        dataset.addSeries(averageSeries);
        JFreeChart chart = ChartFactory.createXYLineChart(
                stock.getCompanyName() + " (" + stock.getTicker() + ")",
                "Date", // x-axis Label
                "Close Price", // y-axis Label
                dataset, // Dataset
                PlotOrientation.VERTICAL, // Plot Orientation
                true, // Show Legend
                true, // Use tooltips
                false // Configure chart to generate URLs?
                );

然后我尝试将 x 轴转换为简单的日期格式，如下所示：

XYPlot plot = (XYPlot) chart.getPlot();
DateAxis axis = (DateAxis) plot.getDomainAxis();
axis.setDateFormatOverride(new SimpleDateFormat("dd-MM-yyyy")); 

当我运行这个时，我得到以下异常：

java.lang.ClassCastException：org.jfree.chart.axis.NumberAxis 无法转换为 org.jfree.chart.axis.DateAxis

有人可以告诉我我做错了什么吗？

根据将日期/时间添加到 JFreeChart 图表 https://stackoverflow.com/q/12272679/230513:

“……你正在使用ChartFactory.createXYLineChart()，这会创建一个NumberAxis对于域。相反，使用ChartFactory.createTimeSeriesChart()，这会创建一个DateAxis对于域。”——trashgod https://stackoverflow.com/users/230513/trashgod