Java中使用MATLAB作图 why 里面的弧线不显示

[manufacture]

matlab 2010b
java version jdk1.7.0_25
________________________________
import com.mathworks.toolbox.javabuilder.*;
import plotdemo.plotter;

public class createplot {
public static void main(String[] args)
{

MWNumericArray x = null; /* Array of x values */
MWNumericArray y = null; /* Array of y values */
plotter thePlot = null; /* Plotter class instance */
int n = 20; /* Number of points to plot */

try
{
/* Allocate arrays for x and y values */
int[] dims = {1, n};
x = MWNumericArray.newInstance(dims,
MWClassID.DOUBLE, MWComplexity.REAL);
y = MWNumericArray.newInstance(dims,
MWClassID.DOUBLE, MWComplexity.REAL);

/* Set values so that y = x^2 */
for (int i = 1; i <= n; i++)
{
x.set(i, i);
y.set(i, i*i);
}

/* Create new plotter object */
thePlot = new plotter();

/* Plot data */
thePlot.drawplot(x, y);
thePlot.waitForFigures();
}

catch (Exception e)
{
System.out.println("Exception: " + e.toString());
}

finally
{
/* Free native resources */
MWArray.disposeArray(x);
MWArray.disposeArray(y);
if (thePlot != null)
thePlot.dispose();
}
}


}


why 结果出来就单单显示窗口，没有内容。:(