JasperReport JRDesign Implementation

Question

There are very few Java-only (no XML) JasperReport examples out there. I am attempting to create a simple pie chart programmatically (in Java) and am getting stuck in some of the implementation.

Please note: I have been using iReport Designer for several days now in order to udnerstand the auto-generated JRXML that gets generated, and now believe I have pie chart JRXML pretty well understood. But I need a pure Java implementation here, one that uses no XML at all. So using the JRXmlLoader isn't an option either, partially because I just want to learn the Java API.

Let me begin by stating that I will be feeding the pie chart from a JRBeanArrayDataSource that uses my own PieSlice POJOs:

public class PieSlice
{
    private String label;
    private Double value;

    public PieSlice()
    {
        this("", -1);
    }

    public PieSlice(String lbl, Double val)
    {
        setLabel(lbl);
        setValue(val);
    }

    public String getLabel()
    {
        return label;
    }

    public String getValue()
    {
        return value;
    }
}

I will then create a factory for the data source and feed it to the JasperFillManager as follows:

public class PieSliceFactory
{
    private static String[] slices = 
    {
        new PieSlice("Fizz", 75.0),
        new PieSlice("Buzz", 25.0);
    };

    public static getSlices()
    {
        return ArrayList.asList(slices);
    }
}

JasperReport jasperReport = JasperFillManager.fillReport(jasperDesign, new JRBeanArrayDataSource(PieSliceFactory.getSlices()));

This should fill the report's pie chart with 2 slices. I am struggling with the JasperDesign object. Normally, the JRXML to support this would look like:

<pieDataset>
    <keyExpression><![CDATA[$F{PieSlice}.label]]></keyExpression>
    <valueExpression><![CDATA[$F{PieSlice}.weight]]></valueExpression>
</pieDataset>

Thus for every record (bean) returned by the datasource (in this case 2), that record's "label" property is fed into the pie chart as the current slice's category/key, and that record's "value" is fed into the chart as the current slice's value.

My problem is that the Java JasperDesign API doesn't seem to support this (at least to a newbie). I would expect to see the API capable of something along the following lines:

JRDesignChart piechart = new JRDesignChart();
JRDesignChartDataset pieDataset = new JRDesignChartDataset();

JRExpression pieLabelExrepssion, pieValueExpression;
pieLabelExpression = new JRExpression(java.lang.String, "$F{PieSlice}.label");
pieValueExpression = new JRExpression(java.lang.Double, "$F{PieSlice}.value");

pieDataset.setKeyExpression(pieLabelExpression);
pieDataset.setValueExpression(pieValueExpression();

piechart.addDataset(pieDataset);

But to my suprise, JRDesignChartDataset does not have methods/properties for the <keyExpression> and <valueExpression> tags present in JRXML.

How can I accomplish this? What JRDesign classes/methods should I be using to map my PieSlice properties (label & value) to the <pieDataset> key/value expressions?

Thanks in advance for any and all help.

GenericJon GenericJon · Accepted Answer · 2011-11-10T23:42:22

You're close to the solution. It might help if you think of JRDesignChartDataset as an abstract class (Actually, it probably should be an abstract class), as instantiating it doesn't really help you get anywhere.

Each different type of chart has a corresponding dataset type, which are all subclasses of JRDesignChartDataset. For a pie chart you'll need to use JRDesignPieDataset, which has the methods setKeyExpression() and setValueExpression() that you've been looking for.

You'll probably gather all of this from looking at the javadoc, but these methods are actually deprecated. Instead of setting the expressions directly you should create a JRDesignPieSeries object and call the methods there, then add this to your chart by using addPieSeries()

JasperReport JRDesign Implementation

1 Answers