e597. creating a gray version of an icon.txt

这里面包含了一百多个JAVA源文件

public Icon toGray(Icon icon) {
        if (icon instanceof ImageIcon) {
            Image grayImage = GrayFilter.createDisabledImage(((ImageIcon)icon).getImage());
            return new ImageIcon(grayImage);
        }
        // Cannot convert
        return null;
    }