Re: how to clear the image from jpanel

From:

"John B. Matthews" <nospam@nospam.invalid>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 28 Oct 2010 14:50:45 -0400

Message-ID:

<nospam-E1B36D.14504528102010@news.aioe.org>

In article <ddhyo.3138$lM.1269@newsfe23.iad>,
Knute Johnson <nospam@rabbitbrush.frazmtn.com> wrote:

On 10/28/2010 6:30 AM, jimgardener wrote:

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?

[...]

If no image gets loaded, set the reference to null and test for that
in the paintComponent() method and don't draw the image just clear
the background.

Knute's right; and if you forget the test, as I have sometimes done, the
drawImage() method "does nothing if img is null."

<http://download.oracle.com/javase/6/docs/api/java/awt/Graphics.html>

--
John B. Matthews
trashgod at gmail dot com
<http://sites.google.com/site/drjohnbmatthews>