// CategoryDataset dataset1 = createDataset1();
NumberAxis rangeAxis1 = new NumberAxis("Value");
rangeAxis1.setStandardTickUnits(NumberAxis.createIntegerTickUnits());
LineAndShapeRenderer renderer1 = new LineAndShapeRenderer();
renderer1.setBaseItemLabelGenerator(new StandardCategoryItemLabelGenerator());
CategoryPlot subplot1 = new CategoryPlot(dataset, null, rangeAxis1, renderer1);
subplot1.setDomainGridlinesVisible(true);
// CategoryDataset dataset2 = createDataset2();
NumberAxis rangeAxis2 = new NumberAxis("Value");
rangeAxis2.setStandardTickUnits(NumberAxis.createIntegerTickUnits());
BarRenderer renderer2 = new BarRenderer();
renderer2.setBaseItemLabelGenerator(new StandardCategoryItemLabelGenerator());
CategoryPlot subplot2 = new CategoryPlot(dataset, null, rangeAxis2, renderer2);
subplot2.setDomainGridlinesVisible(true);
CategoryAxis domainAxis = new CategoryAxis("Category");
CombinedDomainCategoryPlot plot = new CombinedDomainCategoryPlot(domainAxis);