Display percentage in pie chart

Hi,

There were several posts on this forum about how to display the percentage value corresponding to each slice in a pie chart.

You need to use a chart customizer and associate it with your chart element in order to control the content of the labels by setting a label generator.

The label expression inside the chart dataset cannot be used because there is no way to calculate percentages there.

So this can be achieved only by setting a specially configured label generator to the JFreeChart object like seen in the chart customizer implementation below:

import net.sf.jasperreports.engine.JRChart;
import net.sf.jasperreports.engine.JRChartCustomizer;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.labels.StandardPieSectionLabelGenerator;
import org.jfree.chart.plot.PiePlot;

public class PieChartCustomizer implements JRChartCustomizer
{

    public void customize(JFreeChart jFreeChart, JRChart jrChart)
    {
        PiePlot piePlot = (PiePlot) jFreeChart.getPlot();
        StandardPieSectionLabelGenerator labelGenerator 
        	= new StandardPieSectionLabelGenerator("{0} {1} {2}"«»);
        piePlot.setLabelGenerator(labelGenerator);
        piePlot.setLegendLabelGenerator(labelGenerator);
    }

}

Note that the place holders in the standard label generator have special meanings and {2} is for the percentage. They are all explained here:

http://www.jfree.org/jfreechart/api/gjdoc/org/jfree/chart/labels/StandardPieSectionLabelGenerator.html

Put the chart customizer class in the classpath of your application and associate it with your chart by setting customizerClass="PieChartCustomizer" on your chart element.

I hope this helps.

Teodor

Hi Teodord,

Your solution works fine. I try to use the label expression inside the dataset, to avoid to change the custumizer every time I went to change the label format. With a little change in your code, it can be done.

  public void customize(JFreeChart jFreeChart, JRChart jrChart) {
    

    JRFillPieDataset dataset = (JRFillPieDataset) jrChart.getDataset();
  
    if (dataset.getLabelExpression() != null) {
      String label = dataset.getLabelExpression().getText();
      label = label.substring(1, label.length() - 1);
      PiePlot piePlot = (PiePlot) jFreeChart.getPlot();
      StandardPieSectionLabelGenerator labelGenerator = 
        new StandardPieSectionLabelGenerator(label);
      piePlot.setLabelGenerator(labelGenerator);
      piePlot.setLegendLabelGenerator(labelGenerator);
    }
    
  }

I hope this can help!

Luiz Augusto Ruiz

Hi Teodor,

I tried to use the Customizer as specified in this post but it isn't working for me. Here's the code I tried:

public class PieChartCustomizer implements JRChartCustomizer

{

@Override

public void customize(JFreeChart jFreeChart, JRChart jrChart)

{

PiePlot piePlot = (PiePlot) jFreeChart.getPlot();

StandardPieSectionLabelGenerator labelGenerator

= new StandardPieSectionLabelGenerator("{0} {2}");

piePlot.setLabelGenerator(labelGenerator);

piePlot.setLegendLabelGenerator(labelGenerator);

}

}

Then implementing the class like this:

JRDesignChart jrPieChart = new JRDesignChart(jasperDesign,net.sf.jasperreports.engine.JRChart.CHART_TYPE_PIE);

...

jrPieChart.setCustomizerClass("PieChartCustomizer");

...

As soon as that last line to setCustomizerClass runs that's the last I see of the method.

What am I doing wrong?

Thanks in advance for your help.

Hi Teodor,
I tried to use the Customizer as specified in this post but it isn't working for me. Here's the code I tried:

public class PieChartCustomizer implements JRChartCustomizer
{
@Override
public void customize(JFreeChart jFreeChart, JRChart jrChart)
{
PiePlot piePlot = (PiePlot) jFreeChart.getPlot();
StandardPieSectionLabelGenerator labelGenerator
= new StandardPieSectionLabelGenerator("{0} {2}");
piePlot.setLabelGenerator(labelGenerator);
piePlot.setLegendLabelGenerator(labelGenerator);
}
}

Then implementing the class like this:

JRDesignChart jrPieChart = new JRDesignChart(jasperDesign,net.sf.jasperreports.engine.JRChart.CHART_TYPE_PIE);
...
jrPieChart.setCustomizerClass("PieChartCustomizer");
...

As soon as that last line to setCustomizerClass runs that's the last I see of the method.

What am I doing wrong?

Thanks in advance for your help.