The preview panel shows the selected color in a particular context. The default preview panel colors some text with the selected color. 
It may be desirable to change the preview panel to a more relevant setting. For example, if the color chooser is used to color an image, a miniature version of the image can be shown in the preview panel. 

    JColorChooser chooser = new JColorChooser();
    chooser.setPreviewPanel(new MyPreviewPanel(chooser));
    
    // This preview panel simply displays the currently selected color.
    public class MyPreviewPanel extends JComponent {
        // The currently selected color
        Color curColor;
    
        public MyPreviewPanel(JColorChooser chooser) {
            // Initialize the currently selected color
            curColor = chooser.getColor();
    
            // Add listener on model to detect changes to selected color
            ColorSelectionModel model = chooser.getSelectionModel();
            model.addChangeListener(new ChangeListener() {
                public void stateChanged(ChangeEvent evt) {
                    ColorSelectionModel model = (ColorSelectionModel)evt.getSource();
    
                    // Get the new color value
                    curColor = model.getSelectedColor();
                }
            }) ;
    
            // Set a preferred size
            setPreferredSize(new Dimension(50, 50));
        }
    
        // Paint current color
        public void paint(Graphics g) {
            g.setColor(curColor);
            g.fillRect(0, 0, getWidth()-1, getHeight()-1);
        }
    }