Nothing says you have to use a TimeSeries or RegularTimePeriod. The factory method ChartFactory.createTimeSeriesChart() will accept any XYDataset in which the domain represents milliseconds from the Java epoch. The example below extends AbstractXYDataset to synthesize a series of days. Your implementation would have to normalize the Excel dates, which use a different epoch.
Addendum: Apache POI includes static DateUtil.getJavaDate() methods to perform the conversion. The resulting times can be used directly in your chosen data set. A complete example may be found here.
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import java.awt.Dimension;
import java.text.DateFormat;
import java.util.Date;
import javax.swing.JFrame;
import org.jfree.chart.*;
import org.jfree.chart.axis.DateAxis;
import org.jfree.chart.plot.XYPlot;
import org.jfree.data.xy.AbstractXYDataset;
import org.jfree.data.xy.XYDataset;
/** @see https://mcmap.net/q/1008616/-converting-a-jfreechart-timeseries-series-with-day-data-to-week-or-month-data */
public class AbstractXYTest {
private static XYDataset createDataset() {
return new AbstractXYDataset() {
private static final int N = 16;
private final long t = new Date().getTime();
@Override
public int getSeriesCount() {
return 1;
}
@Override
public Comparable getSeriesKey(int series) {
return "Data";
}
@Override
public int getItemCount(int series) {
return N;
}
@Override
public Number getX(int series, int item) {
return Double.valueOf(t + item * 1000 * 3600 * 24);
}
@Override
public Number getY(int series, int item) {
return Math.pow(item, 1.61);
}
};
}
private static JFreeChart createChart(final XYDataset dataset) {
JFreeChart chart = ChartFactory.createTimeSeriesChart(
"Test", "Day", "Value", dataset, false, false, false);
XYPlot plot = (XYPlot) chart.getPlot();
DateAxis domain = (DateAxis) plot.getDomainAxis();
domain.setDateFormatOverride(DateFormat.getDateInstance());
return chart;
}
public static void main(String[] args) {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
XYDataset dataset = createDataset();
JFreeChart chart = createChart(dataset);
ChartPanel chartPanel = new ChartPanel(chart) {
@Override
public Dimension getPreferredSize() {
return new Dimension(800, 300);
}
};
f.add(chartPanel);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
}
