Would someone please point me to a working example JFreeChart\'s XYSplineRenderer?
Although I've never seen the example, XYSplineRendererDemo1.java is one that may be found among the demos. All the demos are included with the developer guide†, which I recommend highly.
If you want to assay an example of your own, note that XYSplineRenderer is an XYLineAndShapeRenderer, so start with a matching ChartFactory. It looks like they all take an XYDataset.
†Disclaimer: Not affiliated with Object Refinery Limited; just a satisfied customer and very minor contributor.