Re: how to clear the image from jpanel

I have an ImagePanel subclassed from JPanel ,where I can set an image

class ImagePanel extends JPanel{
    private BufferedImage bi;
    public ImagePanel(){
        super();
    }
    public void setImage(String imagefilename) throws IOException{
        bi = ImageIO.read(new File(imagefilename));
        this.setPreferredSize(new Dimension(bi.getWidth(),bi.getHeight()));

        this.revalidate();
        this.repaint();
         }
        @Override
    public void paintComponent(Graphics g) {
         g.setColor(getBackground());
         g.fillRect(0,0,getWidth(),getHeight());
         g.drawImage(bi,0,0,null);
         }
}

I can set the image by giving an image filename.But I wish to clear
the previous image from the panel,thus showing a blank image panel,if
a user supplies an invalid image name.
How can I do this?Can someone please tell me?
thanks

jim