Q:

Get an access to JFrame components

How to get an access to the XYSeries and XYPlot placed on JFrame? Of course, I can use the variable names series and plot, but my question refers to the functional way to access these components, i.e. f.getContentPane()... This is useful when the function returns JFrame.
JFrame f = new JFrame(title);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setLayout(new BorderLayout(0, 5));
XYSeries series = new XYSeries("");
XYDataset data = createDataset(series,0,indf,oldpop);
JFreeChart chart = ChartFactory.createScatterPlot(title, xtitle, ytitle, data, PlotOrientation.VERTICAL, false, true, false);
XYPlot plot = chart.getXYPlot();
XYLineAndShapeRenderer renderer =
                (XYLineAndShapeRenderer) plot.getRenderer();
renderer.setBaseShapesVisible(true);          plot.getDomainAxis().setStandardTickUnits(NumberAxis.createIntegerTickUnits());
ChartPanel chartPanel = new ChartPanel(chart);
f.add(chartPanel, BorderLayout.CENTER);
chartPanel.setMouseWheelEnabled(true);
chartPanel.setHorizontalAxisTrace(true);
chartPanel.setVerticalAxisTrace(true);
JPanel panel = new JPanel(new FlowLayout(FlowLayout.RIGHT));
f.add(panel, BorderLayout.SOUTH);

A:

ChartPanel is JComponent which renders JFreeChart; both XYSeries and XYPlot are components, these objects used by JFreeChart. Since they're not components, you can't access them by traversing component hierarchy, you have to get them from ChartPanel and JFreeChart.
Find ChartPanel in the component hierarchy, use getChart() to get JFreeChart object, and then get the objects you want from it, just like you do in the code above:
XYPlot plot = chart.getXYPlot();

