Gyakran lehet szükség a bizonytalan eredetű Icon objektumok Image-é konvertálására. Ha az Icon interface-el rendelkező objektum eleve egy IconImage, akkor nyert ügyünk van, de nem lehetünk benne biztosak. További problémákat okozhat, ha pl. UI ikont használunk, amely az UIManager getIcon() metódusától származik. Ezeknek az ikonoknak a megjelenítésével is gondok lehetnek.

Icon ► Image konvertáló metódus

public static Image iconToImage(Icon icon) {
        if (icon instanceof ImageIcon) {
            return ((ImageIcon) icon).getImage();
        } else {
            int w = icon.getIconWidth();
            int h = icon.getIconHeight();

            GraphicsEnvironment ge =
                    GraphicsEnvironment.getLocalGraphicsEnvironment();
            GraphicsDevice gd = ge.getDefaultScreenDevice();
            GraphicsConfiguration gc = gd.getDefaultConfiguration();
            BufferedImage image;
            if (w > 0 && h > 0) {
                image = new BufferedImage(icon.getIconWidth(),
                        icon.getIconHeight(), BufferedImage.TYPE_INT_ARGB);
            } else {
                image = new BufferedImage(1, 1, BufferedImage.TYPE_INT_ARGB);
            }
            Graphics2D g = image.createGraphics();
            icon.paintIcon(null, g, 0, 0);
            g.dispose();
            return image;
        }
    }

Biztonságos ikon

public class SafeIcon implements Icon {

    private Icon wrappee;
    private Icon standIn;

    public SafeIcon(Icon wrappee) {
        this.wrappee = wrappee;
    }

    @Override
    public int getIconHeight() {
        return wrappee.getIconHeight();
    }

    @Override
    public int getIconWidth() {
        return wrappee.getIconWidth();
    }

    @Override
    public void paintIcon(Component c, Graphics g, int x, int y) {
        if (standIn == this) {
            paintFallback(c, g, x, y);
        } else if (standIn != null) {
            standIn.paintIcon(c, g, x, y);
        } else {
            try {
               wrappee.paintIcon(c, g, x, y);
            } catch (ClassCastException e) {
                createStandIn(e, x, y);
                standIn.paintIcon(c, g, x, y);
            }
        }
    }

    /**
     * @param e
     */
    private void createStandIn(ClassCastException e, int x, int y) {
        try {
            Class<?> clazz = getClass(e);
            JComponent standInComponent = getSubstitute(clazz);
            standIn = createImageIcon(standInComponent, x, y);
        } catch (Exception e1) {
            // something went wrong - fallback to this painting
            standIn = this;
        }
    }

    private Icon createImageIcon(JComponent standInComponent, int x, int y) {
        BufferedImage image = new BufferedImage(getIconWidth(),
                getIconHeight(), BufferedImage.TYPE_INT_ARGB);
          Graphics g = image.createGraphics();
          try {
              wrappee.paintIcon(standInComponent, g, 0, 0);
              return new ImageIcon(image);
          } finally {
              g.dispose();
          }
    }

    /**
     * @param clazz
     * @throws IllegalAccessException
     */
    private JComponent getSubstitute(Class<?> clazz) throws IllegalAccessException {
        JComponent standInComponent;
        try {
            standInComponent = (JComponent) clazz.newInstance();
        } catch (InstantiationException e) {
            standInComponent = new AbstractButton() {

            };
            ((AbstractButton) standInComponent).setModel(new DefaultButtonModel());
        }
        return standInComponent;
    }

    private Class<?> getClass(ClassCastException e) throws ClassNotFoundException {
        String className = e.getMessage();
        className = className.substring(className.lastIndexOf(" ") + 1);
        return Class.forName(className);

    }

    private void paintFallback(Component c, Graphics g, int x, int y) {
        g.drawRect(x, y, getIconWidth(), getIconHeight());
        g.drawLine(x, y, x + getIconWidth(), y + getIconHeight());
        g.drawLine(x + getIconWidth(), y, x, y + getIconHeight());
    }

}