help with understanding interface-declaration of an object
<p>could someone please explain this java code for me. i find it really hard to understand.</p>

<pre><code>protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
    String firstName = request.getParameter("firstName").toString();
    processRequest(request, response);
}
</code></pre>

<p>so request is an object of the interface class HttpServletRequest which got some empty methods.</p>

<ol>
<li><p>but how can it return any data if the method getParameter() is empty.</p></li>
<li><p>and also, i cant find getParameter() in the HttpServletRequest interface. But shouldn´t it be one, cause request is declared as a HttpServletRequest and thus own all its methods and fields?</p></li>
<li><p>and which class is toString() coming from.</p></li>
</ol>
