error occured in following page ... how to resolve it?

// to convert image into thumbnail i used following code. But netbeans has given me following error ....wht i shud do???????? i m java beginner so plz explain in smooth way....

error is::::

Exception in thread "main" java.lang.IllegalArgumentException: Width (-1) and height (-1) cannot be <= 0 at java.awt.image.DirectColorModel.createCompatibleWritableRaster(DirectColorModel.java:999) at java.awt.image.BufferedImage.(BufferedImage.java:312) at demo.CreateThumbnail.saveThumbnail(CreateThumbnail.java:64) at demo.CreateThumbnail.main(CreateThumbnail.java:90) Java Result: 1

code:

package demo;

import java.awt.Graphics; import java.awt.Image; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import javax.imageio.ImageIO; import javax.swing.ImageIcon;

public class CreateThumbnail { public static final int VERTICAL = 0; public static final int HORIZONTAL = 1;

    public static final String IMAGE_JPEG = "jpeg";
    public static final String IMAGE_JPG = "jpg";
    public static final String IMAGE_PNG = "png";

    private ImageIcon image;
    private ImageIcon thumb;

    public CreateThumbnail(Image image)
    {
        this.image = new ImageIcon(image);
    }

    public CreateThumbnail(String fileName)
    {
        image = new ImageIcon(fileName);
    }

    public Image getThumbnail(int size, int dir)
    {
        if (dir == HORIZONTAL)
        {
            thumb = new ImageIcon(image.getImage().getScaledInstance(size, -1, Image.SCALE_SMOOTH));
        }
        else
        {
            thumb = new ImageIcon(image.getImage().getScaledInstance(-1, size, Image.SCALE_SMOOTH));
        }
        return thumb.getImage();
    }

    public Image getThumbnail(int size, int dir, int scale)
    {
        if (dir == HORIZONTAL)
        {
            thumb = new ImageIcon(image.getImage().getScaledInstance(size, -1, scale));
        }
        else
        {
            thumb = new ImageIcon(image.getImage().getScaledInstance(-1, size, scale));
        }
        return thumb.getImage();
    }

    public void saveThumbnail(File file, String imageType)
    {
        if (thumb != null)
        {
            BufferedImage bi = new BufferedImage(
                thumb.getIconWidth(),
                thumb.getIconHeight(),
                BufferedImage.TYPE_INT_RGB
            );
            Graphics g = bi.getGraphics();
            g.drawImage(thumb.getImage(), 0, 0, null);
            try
            {
                ImageIO.write(bi, imageType, file);
            }
            catch (IOException ioe)
            {
                System.out.println("Error occured saving thumbnail");
            }
        }
        else
        {
            System.out.println("Thumbnail has not yet been created");
        }
    }

    public static void main(String [] args)
    {
        CreateThumbnail ct = new CreateThumbnail("image.jpg");
        ct.getThumbnail(100, CreateThumbnail.HORIZONTAL);
        ct.saveThumbnail(new File("thumb.jpg"), CreateThumbnail.IMAGE_JPEG);
    }

}