How Can I Avoid Random Errors When Updating JFreeChart Series in a GUI?

Random Errors When Changing Series Using JFreeChart

When developing a GUI that displays the results of background calculations, a common task is to update the graph's data as new information becomes available. Using JFreeChart, this can be achieved by modifying the underlying dataset. However, if the dataset is changed too frequently or in an unsynchronized manner, errors might arise, such as "Series index out of bounds" or "index out of bounds" exceptions.

To resolve these issues, it is recommended to update the dataset from the process() method of a SwingWorker, which ensures thread safety. Additionally, if the domain of the graph represents the number of iterations rather than time, it is appropriate to use a NumberAxis instead of a DateAxis.

Example:

The following code demonstrates how to update a line chart in real-time using a SwingWorker:

private XYSeries series = new XYSeries("Result");
...
@Override
protected void process(List<Double> chunks) {
    for (double d : chunks) {
        label.setText(df.format(d));
        series.add(++n, d);
    }
}

This code snippet uses a XYSeries to store data points and updates the series in the process() method of the SwingWorker. The label is also updated to display the current value.

Additional Considerations:

• Use NumberAxis for both domain and range when the domain represents the number of iterations rather than time.
• Ensure that the dataset is updated from a thread-safe method, such as the process() method of a SwingWorker.
• Avoid making frequent updates to the dataset, as this can cause performance issues.

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