Clustering bars in a bar chart with the same category

Question

My question is very similar to the question asked in this SO link

Create barchart using jfreechart with bars of same category together

If I run the below example, I get the chart as an image, (image attached)

DefaultCategoryDataset dataset = new DefaultCategoryDataset();
dataset.setValue(2, "Lesson-1", "27-sep-2012");
dataset.setValue(7, "Lesson-2", "27-sep-2012");
dataset.setValue(4, "Lesson-3", "27-sep-2012");

JFreeChart chart = ChartFactory.createBarChart(
    "BarChart using JFreeChart", "Student sample", "Marks sample", dataset,
    PlotOrientation.VERTICAL, true, true, false);
chart.setBackgroundPaint(Color.yellow);
chart.getTitle().setPaint(Color.blue);
CategoryPlot plot = chart.getCategoryPlot();

BarRenderer br = (BarRenderer) plot.getRenderer();
br.setItemMargin(0.7);
try {
    ChartUtilities.saveChartAsJPEG(new File(
        "D:/jfreeimages/sample.jpeg"), chart, 500, 300);
} catch (IOException e) {
    e.printStackTrace();
}

for the date 27-sep-2012, i need all the bars to be clustered and to be displayed without any gaps. Many of them suggested me to have lesser margin for barRenderer (code below)

BarRenderer br =(BarRenderer) plot.getRenderer() ;
br.setItemMargin(0.0);

but this makes the size of the bar very bigger, I want the size of the bar as in the attached image only. Please help.

Answer 1

In addition to setItemMargin(0) in the renderer, you may be able to adjust the axis margins and panel size to get the desired effect.

import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JFrame;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.CategoryAxis;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.renderer.category.BarRenderer;
import org.jfree.data.category.DefaultCategoryDataset;

/**
 * @see http://stackoverflow.com/a/12659576/230513
 */
public class StudentSample {

    public static void main(String[] args) {
        DefaultCategoryDataset dataset = new DefaultCategoryDataset();
        dataset.setValue(2, "Lesson-1", "27-sep-2012");
        dataset.setValue(7, "Lesson-2", "27-sep-2012");
        dataset.setValue(4, "Lesson-3", "27-sep-2012");

        JFreeChart chart = ChartFactory.createBarChart(
            "BarChart using JFreeChart", "Student sample", "Marks sample",
            dataset, PlotOrientation.VERTICAL, true, true, false);
        chart.setBackgroundPaint(Color.yellow);
        chart.getTitle().setPaint(Color.blue);
        CategoryPlot plot = chart.getCategoryPlot();
        BarRenderer br = (BarRenderer) plot.getRenderer();
        br.setItemMargin(0);
        CategoryAxis domain = plot.getDomainAxis();
        domain.setLowerMargin(0.25);
        domain.setUpperMargin(0.25);

        JFrame f = new JFrame("TreeEditorDemo");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        ChartPanel cp = new ChartPanel(chart){

            @Override
            public Dimension getPreferredSize() {
                return new Dimension(300, 300);
            }
        };
        f.add(cp);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);

        //try {
        //    ChartUtilities.saveChartAsJPEG(
        //        new File("temp.jpg"), chart, 300, 300);
        //} catch (IOException e) {
        //    e.printStackTrace();
        //}
    }
}