private static CategoryDataset createDataset() {
        
        // row keys...
        String series1 = "First";
        String series2 = "Second";
        String series3 = "Third";

        // column keys...
        String category1 = "Category 1";
        String category2 = "Category 2";
        String category3 = "Category 3";
        String category4 = "Category 4";
        String category5 = "Category 5";

        // create the dataset...
        DefaultCategoryDataset dataset = new DefaultCategoryDataset();

        dataset.addValue(1.0, series1, category1);
        dataset.addValue(4.0, series1, category2);
        dataset.addValue(3.0, series1, category3);
        dataset.addValue(5.0, series1, category4);
        dataset.addValue(5.0, series1, category5);

        dataset.addValue(5.0, series2, category1);
        dataset.addValue(7.0, series2, category2);
        dataset.addValue(6.0, series2, category3);
        dataset.addValue(8.0, series2, category4);
        dataset.addValue(4.0, series2, category5);

        dataset.addValue(4.0, series3, category1);
        dataset.addValue(3.0, series3, category2);
        dataset.addValue(2.0, series3, category3);
        dataset.addValue(3.0, series3, category4);
        dataset.addValue(6.0, series3, category5);
        
        return dataset;