categoryplot.setDomainGridlinesVisible(true);
CategoryAxis categoryaxis = categoryplot.getDomainAxis();
categoryaxis.setCategoryLabelPositions(CategoryLabelPositions.UP_45);
categoryaxis.setLowerMargin(0.0D);
categoryaxis.setUpperMargin(0.0D);
categoryaxis.addCategoryLabelToolTip("Type 1", "The first type.");
categoryaxis.addCategoryLabelToolTip("Type 2", "The second type.");
categoryaxis.addCategoryLabelToolTip("Type 3", "The third type.");
NumberAxis numberaxis = (NumberAxis)categoryplot.getRangeAxis();
numberaxis.setStandardTickUnits(NumberAxis.createIntegerTickUnits());
numberaxis.setLabelAngle(0.0D);