jfreechart 曲线不显示的问题

import javax.swing.JPanel;import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.data.time.Day;
import org.jfree.data.time.Hour;
import org.jfree.data.time.TimeSeries;
import org.jfree.data.time.TimeSeriesCollection;
import org.jfree.data.xy.XYDataset;
import org.jfree.ui.ApplicationFrame;
import org.jfree.ui.RefineryUtilities;public class TimeSeriesTest extends ApplicationFrame {
private static final long serialVersionUID = 1L;
private JFreeChart chart;
private ChartPanel chartPanel; public TimeSeriesTest(String str) {
super(str);
XYDataset localXYDataset = createDataset();
chart = createChart(localXYDataset);
chartPanel = new ChartPanel(chart);
setContentPane(chartPanel);
} @SuppressWarnings("deprecation")
private static XYDataset createDataset() {
Day localDay = new Day();
TimeSeries localTimeSeries1 = new TimeSeries("series1", Hour.class);
localTimeSeries1.add(new Hour(0, localDay), 520.2D);
localTimeSeries1.add(new Hour(2, localDay), 575.1D);
localTimeSeries1.add(new Hour(4, localDay), 564.4D);
localTimeSeries1.add(new Hour(6, localDay), 540.2D);
localTimeSeries1.add(new Hour(8, localDay), 530.2D);
localTimeSeries1.add(new Hour(10, localDay), 555.2D);
localTimeSeries1.add(new Hour(12, localDay), 580.4D);
localTimeSeries1.add(new Hour(14, localDay), 583.2D);
localTimeSeries1.add(new Hour(16, localDay), 595.2D);
localTimeSeries1.add(new Hour(18, localDay), 564.4D);
localTimeSeries1.add(new Hour(20, localDay), 523.2D);
localTimeSeries1.add(new Hour(22, localDay), 515.2D);
localTimeSeries1.add(new Hour(24, localDay), 530.4D);
 TimeSeries localTimeSeries2 = new TimeSeries("series2", Hour.class);
//localTimeSeries2.add(new Hour(0, localDay), 620.2D);
//  localTimeSeries2.add(new Hour(2, localDay), 654.1D);
// localTimeSeries2.add(new Hour(4, localDay), 664.4D);
// localTimeSeries2.add(new Hour(6, localDay), 670.2D);
// localTimeSeries2.add(new Hour(8, localDay), 690.2D);
// localTimeSeries2.add(new Hour(10, localDay), 695.2D);
// localTimeSeries2.add(new Hour(12, localDay), 680.4D);
// localTimeSeries2.add(new Hour(14, localDay), 683.2D);
// localTimeSeries2.add(new Hour(16, localDay), 695.2D);
// localTimeSeries2.add(new Hour(18, localDay), 714.4D);
// localTimeSeries2.add(new Hour(20, localDay), 723.2D);
// localTimeSeries2.add(new Hour(22, localDay), 715.2D);
// localTimeSeries2.add(new Hour(24, localDay), 680.4D); TimeSeriesCollection localTimeSeriesCollection = new TimeSeriesCollection();
localTimeSeriesCollection.addSeries(localTimeSeries1);
localTimeSeriesCollection.addSeries(localTimeSeries2); return localTimeSeriesCollection; } private static JFreeChart createChart(XYDataset xyDataset) {
JFreeChart localChart = org.jfree.chart.ChartFactory.createTimeSeriesChart("test",
"domain", "value", xyDataset, true, true, false); return localChart;
} public static JPanel createDemoPanel() {
JFreeChart chart = createChart(createDataset());
return new ChartPanel(chart);
} public static void main(String[] paramArrayOfString) {
TimeSeriesTest dragValueApp = new TimeSeriesTest("test");
dragValueApp.pack();
RefineryUtilities.centerFrameOnScreen(dragValueApp);
dragValueApp.setVisible(true);
}
}代码如上所示。当之有一条曲线时可以显示。两条曲线当有一条空值时，两条曲线都不显示。