The documentaton indicates that drawPolygon will close the polygon. JDK 1.02. does not for Solaris or Win32.

The code below exeplifies the problem.
// class to provide a frame for testing Image Keys
class PolygonTest extends Frame implements Runnable
{
        static int X = 50;
        static int Y = 50;
        int inner_xpoints[] = { 0, 0, X, X };
        int inner_ypoints[] = { 0, Y, Y, 0 };

        public PolygonTest()
        {
                resize(200,200);
                show();
        }

        public static void main(String[] args)
        {
                new PolygonTest();
        }

        public void run()
        {
        }

        public void paint(Graphics g) {
                g.translate(50,50);
                g.drawPolygon(inner_xpoints, inner_ypoints, 4);
        }
}

public abstract void
drawPolygon(int xPoints[], int yPoints[], int nPoints)

     Draws a closed polygon defined by an array of x points and y points.

     This method draws the polygon defined by npoint line segments, where
     the first npoint-1 line segments are lines segments from [Image] to
     [Image], for [Image]. The last line segment starts at the final point
     and ends at the first point.