JFreeChart Pie Chart Tutorial - Example Exploded Chart

In this tutorial, we will explain how to create a colorful exploded pie chart with label values displayed on the chart using JFreeChart with an example. We will also describe how to convert the resulting chart to a PNG image file using JFreeChart. We had earlier provided a tutorial that described how to color a pie chart using JFreechart with working examples. You can consider this post as an extension to the previous tutorial. At the end of this example, you will see how simple it is to apply various formatting options to pie charts when created using JFreeChart.

The complete Java Code example with relevant explanation to create an exploded pie chart with labels is provided below;

/* This example tutorial demonstrates how to explode a section of Pie chart and display Label Values Using JFreeChart Java API */
import java.io.*;
import org.jfree.data.general.DefaultPieDataset; /* The dataset class, that stores the data on which the Pie Chart is rendered */
import org.jfree.chart.ChartFactory; /* We will use this class to get a JFreeChart object, which will be used for creating the file */
import org.jfree.chart.JFreeChart; 
import org.jfree.chart.plot.PiePlot; /* This class is used to set chart color, explode percent and label information */
import org.jfree.chart.ChartUtilities; /* We will use this class to convert the chart to a PNG image file */
import java.awt.Color; /* To specify the color coordinates for the pie chart */
import org.jfree.chart.labels.StandardPieSectionLabelGenerator; /* Used to display values for the Pie Chart on the Chart */
public class ExplodedPieChartExample {  
     public static void main(String[] args){
        try {
                /* Define Data Range for the Pie Chart */
                DefaultPieDataset myExplodedPieChartData = new DefaultPieDataset();
                /* Define Values for the Pie Chart - Programming Languages Percentage Difficulty */
                myExplodedPieChartData.setValue("Java", 42.9);
                myExplodedPieChartData.setValue("C++", 78.9);
                myExplodedPieChartData.setValue("C", 56.5);
                myExplodedPieChartData.setValue("VB", 87.2);
                myExplodedPieChartData.setValue("Shell Script", 39.5);
                /* With the dataset defined for Pie Chart, we can invoke a method in ChartFactory object to create Pie Chart and Return a JFreeChart object*/
                /* This method returns a JFreeChart object back to us */                
                JFreeChart myExplodedPieChart=ChartFactory.createPieChart("Programming - Exploded Pie Chart Example",myExplodedPieChartData,true,true,false);                
                /* Once we have got the JFreeChart object, it is time to change the colors; specify explode range and labels for the Pie Chart */                
                /* getPlot method of JFreeChart class returns the PiePlot object back to us */                
                PiePlot ColorConfigurator = (PiePlot) myExplodedPieChart.getPlot(); /* get PiePlot object for changing */
                /* We can now use setSectionPaint method to change the color of our chart */
                ColorConfigurator.setSectionPaint("Java", new Color(160, 160, 255));
                ColorConfigurator.setSectionPaint("C++", Color.RED);
                ColorConfigurator.setSectionPaint("C", Color.BLUE);
                ColorConfigurator.setSectionPaint("VB", Color.GREEN);
                ColorConfigurator.setSectionPaint("Shell Script", Color.YELLOW);
                /* We specify explode option for the Pie chart using setExplodePercent method */
                /* This method takes a percentage value and offsets the section of Pie Chart, a percentage value of radius */
                ColorConfigurator.setExplodePercent("Shell Script", 0.30);
                /* A format mask specified to display labels. Here {0} is the section name, and {1} is the value.
                We can also use {2} which will display a percent value */
                ColorConfigurator.setLabelGenerator(new StandardPieSectionLabelGenerator("{0}:{1}"));
                /* Set color of the label background on the pie chart */
                ColorConfigurator.setLabelBackgroundPaint(new Color(220, 220, 220));              
                /* We will now write the chart as a PNG image file. TO do this we will use the ChartUtilities class. org.jfree.chart.ChartUtilities */                
                int width=640; /* Width of the image */
                int height=480; /* Height of the image */
                /* PNG file name */                
                File PieChart=new File("my_pie_chart.png");
                /* Convert JFreeChart to PNG File Using Code below. 
                Note that there is no quality factor here and we use a different method to write a PNG image file */
                ChartUtilities.saveChartAsPNG(PieChart,myExplodedPieChart,width,height); 
        }
        catch (Exception i)
        {
            System.out.println(i);
        }
    }
}

This code produces a PNG image file of a chart which contains an exploded pie. The Pie Chart created by this example is shown below;

Exploded Pie Chart Created Using JFreeChart with Labels

You would have noticed that it is very straightforward to generate an exploded pie chart in JFreeChart.We will cover some more configuration options for a pie chart in the upcoming posts.