code: public static void writeCSVRows(XYSeries series, String path2Dir) {
  
      File newFile = new File(path2Dir + series.getName() + ".csv");
      Writer out = null;
      try {
  
        out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(newFile), "UTF8"));
        String csv = join(series.getXData(), ",") + System.getProperty("line.separator");
        out.write(csv);
        csv = join(series.getYData(), ",") + System.getProperty("line.separator");
        out.write(csv);
        if (series.getExtraValues() != null) {
          csv = join(series.getExtraValues(), ",") + System.getProperty("line.separator");
          out.write(csv);
        }
      } catch (Exception e) {
        e.printStackTrace();
      } finally {
        if (out != null) {
          try {
            out.flush();
            out.close();
          } catch (IOException e) {
            // NOP
          }
        }
      }
    }
docs: Export a XYChart series into rows in a CSV file.
  
  @param series
  @param path2Dir - ex. "./path/to/directory/" *make sure you have the '/' on the end