Color[] c = { Color.RED, Color.WHITE, Color.BLUE, Color.green };
LinearGradientPaint p =
new LinearGradientPaint(start, end, dist, c, CycleMethod.REPEAT);
chart.setPlotterForSeries(system.getModel().getSeries(2),
new TwoSeriesAreaLinePlot(system.getModel().getSeries(1), p));
frame.add(new JScrollPane(chart), BorderLayout.CENTER);
frame.setVisible(true);
}