JFreeChart日期轴格式问题

时间:2014-02-01 20:43:57

标签: java jfreechart graphing

我有时间序列图表。我的x轴是日期,Y轴只是数字。我试图在x轴上格式化日期,但是我一直在例外。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")); 

当我运行时,我得到以下异常:

java.lang.ClassCastException:org.jfree.chart.axis.NumberAxis无法强制转换为org.jfree.chart.axis.DateAxis

有人可以告诉我我做错了吗?

2 个答案:

答案 0 :(得分:7)

根据Adding date/time to JFreeChart graph

  

“...您正在使用ChartFactory.createXYLineChart(),为域名创建NumberAxis。而是使用ChartFactory.createTimeSeriesChart(),为域名创建DateAxis。” - trashgod

答案 1 :(得分:1)

使用

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

XYPlot.setDomainAxis接受ValueAxis,它是DateAxis的父级。这样做可以避免错误。