JFreeChart: update/repaint line graph when a new value is received from another class

Question

This is only my second post, so please forgive me if I am not following the rules correctly yet. I am trying to automatically update a line graph, which was created using the JFreeChart lib. I have been attempting this for a few days now and have referred to the api and followed many examples here, here and here.

I have a method that gets the balance of an account and sends it to another class:

public double credit(double d) 
{
    int bonus = 10;
    if (d >= 500){
        logData = "CREDITED: + £" + df.format(d) + "\n ********** Whohoo a £10.00 bonus has been added to your balance for depositing at least £500 in a single month **********\n";
        currentBalance = currentBalance + d + bonus;
        draw.passBalance(currentBalance);
        draw.paint(currentBalance); //Send balance to Draw class for the graph (CPB)
    } else {
        logData = "CREDITED: + £" + df.format(d) + "\n";
        currentBalance = currentBalance + d;
    } 
    return currentBalance;
}

The class that receives this deals with the data for the graph:

public class Draw extends ApplicationFrame {

private double balance;
private ChartPanel chartPanel;
private JFreeChart chart;
private XYDataset dataset;
private Draw graph;

    public Draw(final String title) {

        super(title);

        dataset = createDataset();
        chart = createChart(dataset);
        chartPanel = new ChartPanel(chart);
        chartPanel.setPreferredSize(new Dimension(750, 350));
        setContentPane(chartPanel);
    }

    private XYDataset createDataset() {

        final XYSeries series1 = new XYSeries("Balance");
        series1.add(1.0, balance);
        series1.add(2.0, balance);
        series1.add(3.0, 100.00);
        series1.add(4.0, 100.00);
        series1.add(5.0, 100.00);
        series1.add(6.0, 100.00);
        series1.add(7.0, 100.00);
        series1.add(8.0, 100.00);
        series1.add(9.0, 100.00);
        series1.add(10.0, 100.00);
        series1.add(11.0, 100.00);
        series1.add(12.0, 100.00);

        System.out.println(balance);

        final XYSeriesCollection dataset = new XYSeriesCollection();
        dataset.addSeries(series1);

        return dataset;
    }

    private JFreeChart createChart(final XYDataset dataset) {

      // create the chart...
      final JFreeChart chart = ChartFactory.createXYLineChart(
            "Account Balance", // chart title
            "Month", // x axis label
            "Balance", // y axis label
            dataset, // data
            PlotOrientation.VERTICAL,
            false, // include legend
            true, // tooltips
            false // urls
    );


      chart.setBackgroundPaint(Color.white);

      final XYPlot plot = chart.getXYPlot();
      plot.setBackgroundPaint(Color.white);
      plot.setDomainGridlinePaint(Color.lightGray);
      plot.setRangeGridlinePaint(Color.lightGray);

      final XYLineAndShapeRenderer renderer = new XYLineAndShapeRenderer();
      renderer.setSeriesLinesVisible(1, true);
      plot.setRenderer(renderer);

      return chart;

  }

    public double passBalance(double d)
    {
     return balance = d;
    }

    public void paint(double d)
    {   
        //System.out.println(balance);
        createDataset();

    }
}

It is my understanding that the chart will be redrawn since all the methods throw a SeriesChangeEvent, but this doesn't appear to be the case.

I'm relatively new to Java and would greatly appreciate any help at all!!!

Thanks

Answer 1

To help isolate the problem, I've reduced your code to a self-contained example that updates a single XYDataItem in an XYSeries in an XYSeriesCollection. Note that each XYDataItem encapsulates two instances of Number; each are Comparable, as required by the XYSeries; add(double x, double y) converts each to Double. Click the Update button to see the effect. Item INDEX should increase by five with each click.

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.xy.XYDataset;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;
import org.jfree.ui.ApplicationFrame;

/** @see https://stackoverflow.com/a/33898324/230513 */
public class Draw extends ApplicationFrame {

    private static final int INDEX = 5;
    private final XYSeries series = new XYSeries("Balance");
    private double balance;

    public static void main(String[] args) {
        EventQueue.invokeLater(() -> {
            new Draw("Test");
        });
    }

    public Draw(final String title) {
        super(title);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        ChartPanel chartPanel = new ChartPanel(createChart(createDataset())) {

            @Override
            public Dimension getPreferredSize() {
                return new Dimension(640, 360);
            }
        };
        add(chartPanel);
        add(new JButton(new AbstractAction("Update") {

            @Override
            public void actionPerformed(ActionEvent e) {
                balance += 5;
                series.addOrUpdate(INDEX, balance);
            }
        }), BorderLayout.SOUTH);
        pack();
        setLocationRelativeTo(null);
        setVisible(true);
    }

    private XYDataset createDataset() {
        for (int i = 0; i < 11; i++) {
            series.add(i, 100.00);
        }
        series.remove(INDEX);
        series.add(INDEX, balance);
        final XYSeriesCollection dataset = new XYSeriesCollection();
        dataset.addSeries(series);
        return dataset;
    }

    private JFreeChart createChart(final XYDataset dataset) {
        final JFreeChart chart = ChartFactory.createXYLineChart(
            "Account Balance", // chart title
            "Month", // x axis label
            "Balance", // y axis label
            dataset, // data
            PlotOrientation.VERTICAL,
            false, // include legend
            true, // tooltips
            false // urls
        );
        return chart;
    }
}