如图所示，该图是从y = 0行开始的，这里我想从
y = 50开始绘制一个图，如何在JFreeChart？中指定呢？

这是一些代码：

public class Profile  {



    double last=0;
    public void generateProfile(int[] pointValue,double[] distance){
        ArrayList pv=new ArrayList();
        ArrayList dist=new ArrayList();

        pv.add(pointValue);
        dist.add(distance);
        for(int i=0;i<pv.size();i++){
            System.out.print(pointValue[i]);
        }
        for(int i=0;i<dist.size();i++){
            System.out.print(distance[i]);
        }


        XYSeries series = new XYSeries("Average Weight");
        for(int i=0;i<pointValue.length;i++){
            if(pointValue[i]!=0){

              series.add(last,pointValue[i]);
              last=distance[i];
            }
         }


      XYDataset xyDataset = new XYSeriesCollection(series);
      JFreeChart chart;

      chart= ChartFactory.createXYAreaChart("Profile View Of Contour", "Distance", "Contour Value", xyDataset, PlotOrientation.VERTICAL, true, true, false);
      ChartFrame frame1=new ChartFrame("XYLine Chart",chart);
      frame1.setVisible(true);
      frame1.setSize(300,300);
    }