public class SessionUtils {
    public static HttpSession getSession() {
        return (HttpSession) FacesContext.getCurrentInstance()
                .getExternalContext().getSession(false);
    }

    public static HttpServletRequest getRequest() {
        return (HttpServletRequest) FacesContext.getCurrentInstance()
                .getExternalContext().getRequest();
    }

    public static String getUserEmail() {
        HttpSession   session = (HttpSession) FacesContext.getCurrentInstance()
                    .getExternalContext().getSession(false);
            return session.getAttribute("email").toString();

    }

    public static String getUserId() {
        HttpSession session = getSession();
        if (session != null)
            return (String) session.getAttribute("userid");
        else
            return null;
    }
    }

a part of index.xhtml



<c:if test='#{authenticateBean.GetSession() ne null}'>
                <c:if test='#{authenticateBean.GetUserEmail() ne "admin@gmail.com"}'>
                    <ul class="links">
                        <li >
                            <h:link value="add" outcome="GoodBasket" />
                        </li>
                    </ul>
                </c:if>
    </c:if>

@Override
    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain) throws IOException, ServletException {

        HttpServletRequest reqt = (HttpServletRequest) request;
        HttpServletResponse resp = (HttpServletResponse) response;
        HttpSession ses = reqt.getSession(false);

        String reqURI = reqt.getRequestURI();

    if ((reqURI.indexOf("/index.xhtml") >= 0))
        chain.doFilter(request, response);
    else
        resp.sendRedirect(reqt.getContextPath() + "/JSFViews/Login.xhtml");
}

public String Login(){
    UsersModel user= userServices.Login(email,password);
    if (user!=null) {
        HttpSession session = SessionUtils.getSession();
        session.setAttribute("email", email);
        return "ProductRegisteration";
    } else {
        FacesContext.getCurrentInstance().addMessage(null, new FacesMessage(FacesMessage.SEVERITY_WARN,
                        "Incorrect Username and Passowrd", "Please enter correct username and Password"));
        return "Login";
    }

    }
 public String GetUserEmail()
    {
        return SessionUtils.getUserEmail();
    }
    public HttpSession GetSession()
    {
        return SessionUtils.getSession();
    }

javax.servlet.ServletException: /JSFViews/index.xhtml @109,86 test="#{authenticateBean.GetUserEmail() ne "admin@gmail.com"}" /JSFViews/index.xhtml @109,86 test="#{authenticateBean.GetUserEmail() ne "admin@gmail.com"}": java.lang.NullPointerException
    javax.faces.webapp.FacesServlet.service(FacesServlet.java:671)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    ir.navayemehr.util.AuthorizationFilter.doFilter(AuthorizationFilter.java:55)