Waterfall Chart - Space between bars

Question

I am using JFreeChart v1.5.0 and creating a waterfall chart with a sample dataset as shown in the code below. I was able to add space to the bars created using createBarChart() with the help of BarRenderer API, but when I created waterfall chart using createWaterFallChart() and tried adding space to the bars using the same BarRenderer API but I could not.

I used setItemMargin(double) API to achieve the output but nothing happened.

private CategoryDataset createDataset() {
    DefaultCategoryDataset dataset = new DefaultCategoryDataset();
    dataset.addValue(15.76, "Series 1", "Group A");
    dataset.addValue(-8.66, "Series 1", "Group B");
    dataset.addValue(4.71, "Series 1", "Group C");
    dataset.addValue(-3.51, "Series 1", "Group  D");
    dataset.addValue(32.64, "Series 1", "Group E");
    return dataset;
}

public JFreeChart createChart() {
    JFreeChart chart = ChartFactory.createWaterfallChart(
          "Waterfall Chart",
          "X-Axis",
          "Y-Axis",
          createDataset(),
          PlotOrientation.VERTICAL,
          true,
          true,
          false
      );

      CategoryPlot plot = (CategoryPlot) chart.getPlot();

      NumberAxis yAxis = (NumberAxis)plot.getRangeAxis();
      yAxis.setRange(0.0, 50.0);
      yAxis.setTickUnit(new NumberTickUnit(10.0));
      BarRenderer renderer = (BarRenderer) plot.getRenderer();
      renderer.setDrawBarOutline(false);

      //Spaces between bars - not working
      renderer.setItemMargin(0.5);

      return chart;
}

Output:

Answer 1

Upon debugging I was able to see that WaterfallBarRenderer ignores the value set by the method renderer.setItemMargin(double).

I was able to add space between bars using the code below.

CategoryPlot plot = (CategoryPlot)chart.getPlot();
CategoryAxis categoryAxis = plot.getDomainAxis();
categoryAxis.setCategoryMargin(0.5);