Minor ticks not showing up on LogAxis in JFreeChart

Question

I'm using JFreeChart to plot some data and using a LogAxis for the range axis. I'm stumped as to why I can't seem to get the minor ticks to show up on the axis, but the grid lines show up fine.

If I don't use the LogAxis I can turn the minor ticks on and off fine using setMinorTickMarksVisible(). Example below:

public ChartOne(){

    XYSeriesCollection xysc = new XYSeriesCollection();

    XYSeries x1 = new XYSeries("Series 1");
    x1.add(0.5, 2);
    x1.add(1, 2.2);
    x1.add(2, 2.4);
    x1.add(10, 2.75);
    x1.add(30, 4);
    x1.add(120, 7);
    xysc.addSeries(x1);

    XYSeries x2 = new XYSeries("Series 2");
    x2.add(0.5, 6);
    x2.add(1, 7);
    x2.add(2, 8);
    x2.add(10, 14);
    x2.add(30, 18);
    x2.add(120, 22);
    xysc.addSeries(x2);

    XYDataset xyd = xysc;

    JFreeChart chart = ChartFactory.createXYLineChart(
            "Data",     
            "Exposure",                     
            "Percentage uptake",                    
            xyd,                 
            PlotOrientation.VERTICAL,
            false,                     
            true,                     
            false                     
            );

    LogAxis xAxis = new LogAxis("exposure time");
    xAxis.setBase(10);
    xAxis.setTickUnit(new NumberTickUnit(1.0, NumberFormat.getInstance(Locale.ENGLISH), 9));

    xAxis.setRange(0.1, 200.0);

    xAxis.setMinorTickMarksVisible(true); //they don't show up

    XYPlot plot = (XYPlot) chart.getPlot();
    plot.setDomainAxis(xAxis);
    plot.setDomainMinorGridlinesVisible(true);
    plot.setDomainGridlinePaint(Color.BLACK);
    plot.setDomainMinorGridlinePaint(Color.BLACK);
    plot.setBackgroundPaint(Color.WHITE);

    ChartPanel chartPanel = new ChartPanel(chart);

    add(chartPanel);

}

public static void main(String[] args) {
    JFrame frame = new JFrame("Chart");

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    frame.getContentPane().add(new ChartOne(), BorderLayout.CENTER);
    frame.pack();
    frame.setVisible(true);

}

Note current x axis (left) and example of the desired x axis effect with minor ticks (right).

Answer 1

LogAxis supports minor ticks for gridlines, as your fragment shows. In contrast LogarithmicAxis allows full customization of tick marks, as shown below. The color and stroke of the tick marks have been exaggerated for emphasis.

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.BasicStroke;
import java.text.NumberFormat;
import javax.swing.JFrame;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.LogarithmicAxis;
import org.jfree.chart.axis.NumberTickUnit;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.plot.XYPlot;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;

//** @see https://stackoverflow.com/a/54097313/230513 */
public class ChartOne {

    public static ChartPanel createChart() {

        XYSeriesCollection dataset = new XYSeriesCollection();
        XYSeries x1 = new XYSeries("Series 1");
        x1.add(0.5, 2);
        x1.add(1, 2.2);
        x1.add(2, 2.4);
        x1.add(10, 2.75);
        x1.add(30, 4);
        x1.add(120, 7);
        dataset.addSeries(x1);
        XYSeries x2 = new XYSeries("Series 2");
        x2.add(0.5, 6);
        x2.add(1, 7);
        x2.add(2, 8);
        x2.add(10, 14);
        x2.add(30, 18);
        x2.add(120, 22);
        dataset.addSeries(x2);

        JFreeChart chart = ChartFactory.createXYLineChart(
            "Data", "Exposure", "Percentage uptake", dataset,
            PlotOrientation.VERTICAL, false,  true, false);

        LogarithmicAxis xAxis = new LogarithmicAxis("Time");
        xAxis.setTickUnit(new NumberTickUnit(1.0, NumberFormat.getInstance(), 9));
                xAxis.setTickMarkInsideLength(2f);
                xAxis.setTickMarkOutsideLength(4f);
                xAxis.setTickMarkPaint(Color.GREEN);
                xAxis.setTickMarkStroke(new BasicStroke(2f));
        xAxis.setMinorTickMarksVisible(true);

        XYPlot plot = (XYPlot) chart.getPlot();
        plot.setDomainAxis(xAxis);
        plot.setDomainMinorGridlinesVisible(true);
        plot.setDomainGridlinePaint(Color.BLACK);
        plot.setDomainMinorGridlinePaint(Color.BLACK);
        plot.setBackgroundPaint(Color.WHITE);
        return new ChartPanel(chart){
            @Override
            public Dimension getPreferredSize() {
                return new Dimension(600, 400);
            }
        };
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(() -> {
            JFrame frame = new JFrame("Chart");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.add(createChart(), BorderLayout.CENTER);
            frame.pack();
            frame.setLocationRelativeTo(null);
            frame.setVisible(true);
        });
    }
}