How to pass data from servlet to JSP without form on JSP page load

Question

I am trying to pass the data from servlet to JSP without forms. I am setting up a data in Servlet and through Dispatcher I am passing it to JSP file. Now when I am running JSP file I am getting error message I even have tried with JSTL as well, my problem is not with JSTL or JSP, problem is I am not able to get the data passed by servlet directly when JSP is ran, so question is can I even directly run JSP file and get the result on UI without forms. intention to this is I want to show Database contents on UI for which I will prepare a connection in servlet and then will pass result-set in JSP which will get displayed on UI without forms I don't want to submit any form just want to show the data of database on UI but through servlet, help me out.

Below is the code:

        Servlet:
        import java.io.IOException;
        import java.util.ArrayList;
        import javax.servlet.ServletException;
        import javax.servlet.http.HttpServlet;
        import javax.servlet.http.HttpServletRequest;
        import javax.servlet.http.HttpServletResponse;
        public class NewClass extends HttpServlet {
           @Override
           protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        ArrayList<String> myList;
         myList = new ArrayList<>();
        myList.add("one");
        myList.add("Two");
        myList.add("Three");
        request.setAttribute("MyList", myList);
        request.getRequestDispatcher("/ToTestPage.jsp").forward(request, response);
        //request.getRequestDispatcher("/ToTestPage.jsp").include(request, response);
           }
        }

JSP File. ToTestJSP:

    <%@page import="java.util.Iterator"%>
    <%@page import="java.util.List"%>
    <%@page import="java.util.ArrayList"%>
    <%@page contentType="text/html" pageEncoding="UTF-8"%>
    <!DOCTYPE html>
    <html>
        <head>
            <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
            <title>JSP Page</title>
        </head>
        <body>
          <body>      
        <%

            ArrayList<String> list = (ArrayList<String>) request.getAttribute("MyList");
            Iterator itr = list.iterator();
            while(itr.hasNext()) {
                String value =  (String) itr.next();
                out.println(value);
            }

        %>
    </body>
        </body>
    </html>

I am getting below error message, when I am just running - ToTestPage.jsp file:

       org.apache.jasper.JasperException: An exception occurred processing JSP page /ToTestPage.jsp at line 22

      19:     <%
      20:        
      21:         ArrayList<String> list = (ArrayList<String>)    request.getAttribute("MyList");
      22:         Iterator itr = list.iterator();
      23:         while(itr.hasNext()) {
      24:             String value =  (String) itr.next();
      25:             out.println(value);

Below is my Web Config File:

    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>  
    <servlet>
        <servlet-name>NewClass</servlet-name>
        <servlet-class>NewClass</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>NewClass</servlet-name>
        <url-pattern>/NewClass</url-pattern>
    </servlet-mapping>
</web-app>

Complete Stack Trace:

Stacktrace:
          org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:580)
        org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:477)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

root cause 
java.lang.NullPointerException
    org.apache.jsp.ToTestPage_jsp._jspService(ToTestPage_jsp.java:103)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:439)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

When you run the JSP you are not running the servlet, try running /NewClass in the browser and it should work. Why this occurred, since you are running the JSP from the browser, the JSP's servlet is requested and it has no attributes set in the request. Therefore to avoid confusion do this in your JSP: if (list != null && !list.isEmpty()) { Iterator itr = list.iterator(); while (itr.hasNext()) { String value = (String) itr.next(); out.println(value); }} — Akhadra, Apr 25 '18 at 08:42
On running newclass I am getting error message HTTP method GET is not supported by this URL — arjunhitachi, Apr 25 '18 at 09:56

How to pass data from servlet to JSP without form on JSP page load

0 Answers0