// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.sps.servlets;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/registration")
public class RegistrationServlet extends HttpServlet {

  @Override
  public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
    String role = request.getParameter("role");
    String name = request.getParameter("name");
    String email = request.getParameter("email");
    List<String> topics = Arrays.asList(request.getParameter("math"), request.getParameter("english"), request.getParameter("other"));

    topics = topics
            .stream()
            .filter(t -> t!= null)
            .collect(Collectors.toList());

    response.setContentType("text/html;");
    response.getWriter().println("<p>Student or tutor? " + role + "</p>");
    response.getWriter().println("<p>Name: " + name + "</p>");
    response.getWriter().println("<p>Email: " + email + "</p>");
    response.getWriter().println("<p>Subject(s): " + topics + "</p>");
  }
}

Add basic servlet that responds with user info