Unable to display center text in ring chart

Vijay Raju :

I am trying to generate a donut or ring chart using jfree chart library. Ringchart was generated successfully but only the problem is centered text inside ring was not displaying. The following is the sample snippet. chart generation code

JFreeChart chart = ChartFactory.createRingChart(heading, dataSet, legend, tooltips, urls);

And centered text related code is like below

RingPlot pie = (RingPlot) chart.getPlot();
pie.setBackgroundPaint(Color.WHITE);
pie.setOutlineVisible(false);
pie.setShadowPaint(null);
pie.setLabelGenerator(null);
pie.setCenterTextMode(CenterTextMode.VALUE);
Font font = new Font("Arial",1,30);
pie.setCenterTextFont(font);
pie.setCenterTextColor(Color.getHSBColor(222, 1, 1));
pie.setSectionDepth(0.1);
pie.setSectionOutlinesVisible(false);
pie.setSeparatorsVisible(false);
pie.setIgnoreZeroValues(false);

I am using jfreechart verison 1.5.0

trashgod :

It's not clear where your fragment is going awry, but this minimal complete example gives the expected result. As an aside, note the use of Font.BOLD for clarity and the use of deriveFont() to minimize the risk of an unfortunate font substitution; see also Initial Threads.

pie.setCenterTextMode(CenterTextMode.VALUE);
pie.setCenterTextFont(pie.getCenterTextFont().deriveFont(Font.BOLD, 30f));
pie.setCenterTextColor(Color.getHSBColor(0, 1, 1));

I tried pie.setCenterText("Vijay");

Instead of CenterTextMode.VALUE; specify CenterTextMode.FIXED:

pie.setCenterTextMode(CenterTextMode.FIXED);
pie.setCenterText("Vijay");

The above code is not setting any value if the first dataset value is zero.

Correct. RingPlot::drawItem() ignores center text unless values exceed the rendering threshold; you can specify a value that passes the threshold yet displays correctly when formatted:

dataset.setValue("Critical", RingPlot.DEFAULT_MINIMUM_ARC_ANGLE_TO_DRAW);

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import javax.swing.JFrame;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.CenterTextMode;
import org.jfree.chart.plot.RingPlot;
import org.jfree.data.general.DefaultPieDataset;

/**
 * @see https://stackoverflow.com/a/56672573/230513
 * @see https://stackoverflow.com/a/37414338/230513
 */
public class TestRing {

    private void display() {
        JFrame f = new JFrame("Test");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        DefaultPieDataset dataset = new DefaultPieDataset();
        dataset.setValue("Critical", new Integer(42));
        dataset.setValue("Important", new Integer(21));
        dataset.setValue("Moderate", new Integer(7));
        dataset.setValue("Low", new Integer(3));
        JFreeChart chart = ChartFactory.createRingChart(
            "Test", dataset, false, true, false);
        RingPlot pie = (RingPlot) chart.getPlot();
        pie.setSimpleLabels(true);
        pie.setCenterTextMode(CenterTextMode.VALUE);
        pie.setCenterTextFont(pie.getCenterTextFont().deriveFont(Font.BOLD, 30f));
        pie.setCenterTextColor(Color.getHSBColor(0, 1, 1));
        f.add(new ChartPanel(chart){
            @Override
            public Dimension getPreferredSize() {
                return new Dimension(400, 400);
            }
        });
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new TestRing()::display);
    }
}