JfreeChart: Stacked Bar Chart and CategoryAxis showing dates

For a CategoryAxis, which is used the for the domain axis in a StackedBarChart, you have considerable flexility with the method setCategoryLabelPositions(). Typical usage is illustrated in the BarChartDemo1 source, shown here.

CategoryAxis domainAxis = plot.getDomainAxis();
domainAxis.setCategoryLabelPositions(
    CategoryLabelPositions.createUpRotationLabelPositions(Math.PI / 6.0));