Unable to custsomize the bar chart bars width

Question

I'm able to generate the bar chart using bar jfreechart library.Coming to bar chart customization unable to reduce the bars (narrow bars instead of normal bars)width like below pic.

I am looking output like first graph but I'm getting output like second graph.

I tried chart generation with jfreechart factory.And some cutomization to bars like font and colors changing and adding own legend to the chart.But bars widths related code is not working.

chart.setBorderVisible(false);
chart.getLegend().setPosition(RectangleEdge.BOTTOM);
Font font = new Font("SansSerif", Font.PLAIN, 12);
chart.getTitle().setFont(font);
CategoryPlot plot = chart.getCategoryPlot();
plot.setNoDataMessage("No data available");
plot.setBackgroundPaint(Color.white);
plot.setAxisOffset(RectangleInsets.ZERO_INSETS);
plot.setFixedLegendItems(chartLegend);
plot.getDomainAxis().setLabelFont(font);
plot.getRangeAxis().setLabelFont(font);
plot.setOutlineVisible(false);
CategoryItemRenderer renderer = plot.getRenderer();
renderer.setDefaultItemLabelGenerator(new StandardCategoryItemLabelGenerator());
renderer.setDefaultItemLabelsVisible(false);
ItemLabelPosition position = new ItemLabelPosition(ItemLabelAnchor.OUTSIDE12, TextAnchor.TOP_CENTER);
renderer.setDefaultPositiveItemLabelPosition(position);
BarRenderer barRenderer = (BarRenderer) renderer;
for (int i = 0; i < plot.getDataset().getRowCount(); i++) {
    if (plot.getDataset().getRowKey(i).equals("FIRST_BAR")) {
        barRenderer.setSeriesPaint(i, Constants.COLOR_RED);
    }
    if (plot.getDataset().getRowKey(i).equals("SECOND_BAR)) {
        barRenderer.setSeriesPaint(i, Constants.COLOR_YELLOW);
    }
    if (plot.getDataset().getRowKey(i).equals("THIRD_BAR")) {
        barRenderer.setSeriesPaint(i, Constants.COLOR_BLUE);
    }
    if (plot.getDataset().getRowKey(i).equals("FOURTH_BAR")) {
        barRenderer.setSeriesPaint(i, Constants.COLOR_GREEN);
    }
}
barRenderer.setDrawBarOutline(false);
barRenderer.setBarPainter(new StandardBarPainter());

any suggestions that could be more helpful to my report generation.