Java EE (Java Enterprise Edition) General Discussion

How Ajax decides, which response it will set to responseXML and which to responseText.

private void writeResponse(HttpServletResponse resp, String output) throws IOException {
resp.setContentType("text/xml");
resp.setHeader("Cache-Control", "no-cache");
//resp.getWriter().write(output);
PrintWriter out = resp.getWriter();
out.write(output);
//out.println(output);
//out.flush();
}

if I use the above function in my servlet, I don't get the responseText, but if I use the following function I get responseText.

private void writeResponse(HttpServletResponse resp, String output) throws IOException {
resp.setContentType("text/xml");
resp.setHeader("Cache-Control", "no-cache");
//resp.getWriter().write(output);
PrintWriter out = resp.getWriter();
//out.write(output);
out.println(output);
out.flush();
}

Please clarify.
regards,
Saptarshi