package services;

import javax.jws.WebMethod;
import javax.jws.WebService;

@WebService(endpointInterface = "services.Hello")
public class Hello
{
    public Hello()
    {

    }

    @WebMethod
    public String getHello()
    {
        return "Hello";
    }
}

@WebServlet("/admin")
public class AdminPage extends HttpServlet
{
@WebServiceRef(wsdlLocation = "http://localhost:8081/hello?wsdl")
private HelloService service;

// ignore the doGET method
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException
{
    HttpSession session = request.getSession();

    if (session.getAttribute("session") != null)
    {
        if (session.getAttribute("session").equals("user"))
        {
            response.setContentType("text/html");
            PrintWriter out = response.getWriter();
            out.println("Forbidden access.");
        }
        else
            response.sendRedirect("/admin.html");
    }
    else
    {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out.println("Please log in.");
    }
}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException
{
    HttpSession session = request.getSession();

    String add = request.getParameter("buttonAdd");
    String read = request.getParameter("buttonRead");
    String register = request.getParameter("buttonRegister");
    String remove = request.getParameter("buttonRemove");
    String update = request.getParameter("buttonUpdate");
    String logOut = request.getParameter("buttonLogOut");

    if(logOut != null)
    {
        session.invalidate();
        response.sendRedirect("/home.html");
    }

    if(add != null)
    {
        // here it genereates the NullPointer
        Hello port = service.getHelloPort();

        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out.println(port.getHello());
    }
}

16-Dec-2017 14:21:10.825 SEVERE [http-nio-8080-exec-9] org.apache.catalina.core.StandardWrapperValve.invoke Servlet.service() for servlet [AdminPage] in context with path [] threw exception
 java.lang.NullPointerException
    at servlets.AdminPage.doPost(AdminPage.java:60)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:661)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.base/java.lang.Thread.run(Thread.java:844)