How do I update my JFreeChart TimeSeries chart every 10 seconds?

Based on this example, I want to update my time series chart every 10 seconds. However, if I use swing Timer to make the chart update every 10 seconds, on the chart it shows that it updated itself only in 1 second even though time elapsed was 10 seconds. Here is my variation, which basically grabs the latest temperature from a location from an online database every 10 seconds and (tries to) plots it on the graph:

/** @see https://stackoverflow.com/questions/5048852 */
public class l extends ApplicationFrame {
TestWeatherTimeLapseService getTemp = new TestWeatherTimeLapseService();  //gets temperature
private static final String TITLE = "Dynamic Series";
private static final int COUNT = 1 ;
private static final int DELAY = 10000;
private Timer timer;

public l(final String title) {
    super(title);
    final DynamicTimeSeriesCollection dataset =
        new DynamicTimeSeriesCollection(1,60, new Second());
    Date date = new Date();
    dataset.setTimeBase(new Second(date));
    dataset.addSeries(gaussianData(), 0, "Gaussian data");
    JFreeChart chart = createChart(dataset);
    this.add(new ChartPanel(chart), BorderLayout.CENTER);
    timer = new Timer(DELAY, new ActionListener() {
        float[] newData = new float[1];
        @Override
        public void actionPerformed(ActionEvent e) {
            newData[0] = randomValue();
            dataset.advanceTime();
            dataset.appendData(newData);
        }
    });
}
private float randomValue() {
    String currTemperature="";
    try {
         currTemperature=getTemp.getWeatherData("Laverton")[1];     //get temperature of laverton
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    float number = Float.parseFloat(currTemperature);
    number=(float) (number-273.15);
    return number;
    }
private float[] gaussianData() {
    float[] a = new float[COUNT];
    a[0] = randomValue();   
    return a;
}
private JFreeChart createChart(final XYDataset dataset) {
    final JFreeChart result = ChartFactory.createTimeSeriesChart(
        TITLE, "time", "milliVolts", dataset, true, true, false);
    final XYPlot plot = result.getXYPlot();
    ValueAxis domain = plot.getDomainAxis();
    domain.setAutoRange(true);
    ValueAxis range = plot.getRangeAxis();
    DateAxis axis = (DateAxis) plot.getDomainAxis();
    axis.setTickUnit(new DateTickUnit(DateTickUnitType.SECOND, 5));
    axis.setDateFormatOverride(new SimpleDateFormat("mm:ss"));

    range.setRange(-10,50);
    return result;
}
public void start() {
    timer.start();
}
public static void main(final String[] args) {
    EventQueue.invokeLater(new Runnable() {
        @Override
        public void run() {
            l demo = new l(TITLE);
            demo.pack();
            RefineryUtilities.centerFrameOnScreen(demo);
            demo.setVisible(true);
            // Run some code;
            demo.start();
        }
    });
}}

Solution

Your DynamicTimeSeriesCollection constructor specified 60 moments, each of one Second duration. As a result, each call to advanceTime() moves the time by one second. One approach is to invoke advanceTime() to match your next reading. Starting from the original example, the following change produces the effect shown for 10-second intervals:

@Override
public void actionPerformed(ActionEvent e) {
    newData[0] = randomValue();
    for (int i = 0; i < 10; i++) {
        dataset.advanceTime();
        dataset.appendData(newData);
    }
}

See also this related discussion of setTimeBase() regarding series initialization. For example, this implementation of gaussianData() changes the data every 10 seconds during the first COUNT seconds.

private float[] gaussianData() {
    float[] a = new float[COUNT];
    for (int i = 0; i < a.length; i++) {
        if (i % 10 == 0) a[i] = randomValue();
    }
    return a;
}