error in casting
<pre><code>public class xyArea{
public static void main(String arg[]){
  XYSeries series = new XYSeries("Average Weight");
  series.add(20.0, 20.0);
  series.add(40.0, 25.0);
  series.add(55.0, 50.0);
  series.add(70.0, 65.0);
  XYDataset xyDataset = new XYSeriesCollection(series);
  JFreeChart chart = ChartFactory.createAreaChart
  ("XY Chart using JFreeChart", "Age", "Weight",
   (CategoryDataset) xyDataset, PlotOrientation.VERTICAL, true, 
  true, false);
  ChartFrame frame1=new ChartFrame("XYArea Chart",chart);
  frame1.setVisible(true);
  frame1.setSize(300,300);
  }
}
</code></pre>

<p>I wrote this code but error below is occured Please guide me :</p>

<p><strong>Exception in thread "main" java.lang.ClassCastException: org.jfree.data.xy.XYSeriesCollection cannot be cast to org.jfree.data.CategoryDataset
    at xyArea.main(xyArea.java:21)</strong></p>
