[hardwired]

Code:

    public static void main(String[] args) {
        File file = new File("images/cougar.jpg");
        String ext = getExtension(file);
        String JPG = "jpg";
        if(JPG.equals(ext))
            System.out.println("equal");
        else
            System.out.println("not equal");
    }

    private static String getExtension(File file) {
        String s = file.getPath();
        int dot = s.lastIndexOf(".");
        if(dot > -1 && dot < s.length())
            return s.substring(dot+1);
        return null;
    }