how to force a JPanel te resize

[Ko Wey]

Please could anyone consider following situation:
I have an instance (thumbnail)of class Thumbnail (that extends a JPanel.)en
It sits in a box.
When some event occurs, thumbnail must redraw itself AND CHANGE IT SIZE.
Alas, the redrawing takes place, but not the resizing. Even if I can overload setMaximumSize() or setPreferredSize(). I must have missed something?
Here is the code (sorry if it to much)

class PictureItLE extends JFrame implements ...{
//members
Thumbnail thumbnail;
       public PictureItLE(){
            super("PictureIt LE");
            //...
            thumbnail = new Thumbnail();
           //throw everything together
   //*************************
   Container cont = getContentPane();
   cont.setLayout(new BorderLayout());
   //....
   JPanel box = new JPanel();
   box.setLayout(new BoxLayout(box,BoxLayout.X_AXIS));
   //box.add(.... lots of things
   box.add(thumbnail);
   box.add(Box.createGlue());
   cont.add(box,BorderLayout.CENTER);
   //...
       }//end constructor
//events*****************************************
//***********************************************
public void selected(SingleFileSelectorEvent e){//home-made event
//here code that retrieves an image from file and sends it
//to the Jpanel thumbnail
//get the file from the SingleFileSelector
Image image = ....//etc
thumbnail.setImage(image);
thumbnail.revalidate(); //CORRECT?
}
//innerclasses***********************************
//***********************************************
class Thumbnail extends JPanel{
private BufferedImage buf = null;
private BufferedImage buf_small = null;
private int width = 300;
private int height = 300;
public Thumbnail(){
super();
this.setBackground(Color.black);
}
public Dimension getPreferredSize(){
return new Dimension(width,height);
}

public Dimension getMaximumSize(){
return new Dimension(width,height);
}
public void setImage(Image image){
//here code to create a bufferedImage (=buf)from the image
//and to make a smaller size BufferedImage (=buf_small)
                //from it
                //.... (works perfect)
                //RESIZING STUFF THAT IS IGNORED. WHY?
if (buf_small!=null){
width = buf_small.getWidth();
height = buf_small.getHeight();
};
setSize(width,height);
setMaximumSize(new Dimension(width,height));        setPreferredSize(new Dimension(width,height));
repaint();
}

public void paintComponent(Graphics g){
super.paintComponent(g);
        Graphics2D g2D = (Graphics2D) g;//cast to Graphics2D
g2D.setColor(Color.darkGray);//reset contents 
g2D.fillRect(0,0,getWidth(),getHeight());
                if (buf_small!=null){
g2D.drawImage(buf_small,0,0,this);
};
}
  

Thanks for your time.

[Nathan Pruett]

Quick suggestion... try to revalidate the component that contains the thumbnail, not the thumbnail itself. I'll look closer at the code later and see if I notice anything else.