how to pass a collection object in response.sendRedirect

Question

in a jsp page say x.jsp ,i have

if (some task =true)
{
//show xml at run time
List <User_Registration> list = dao.selectemailmobile(login); //here m getting data from  Db and m getting it perfectly alright
response.sendredirect("page.jsp?list="+list)
//i wanted to pass this list parameter as List<Bean> list=List<Bean>();
//this page will show xml at run time

}
else 
{
//some status code 
//this working fine 
}

what i tried

1.pass this(List) parameter as list i have shown,but when i'm retrieving it, is says

 cannot cast from string to List<Bean>

for that i also tried to type cast it,but nothing happens.

2.setting that List in session it shows

unchecked cast from object to List<Bean>

3.using request Dispatcher

 i get same cannot cast from string to List<Bean>

my code for that xml page

<%@ page language="java" contentType="text/xml; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@page import="com.xml.*" %>
<%@page import="com.beans.*" %>
<%@page import="java.util.*" %>


<%@page import="com.xml.ForgotPasswordXml"%>
<%!java.util.List<User_Registration> list= null; %>
<%try{
HttpSession session2=request.getSession();
System.out.println("hii");

list=(List<User_Registration>)request.getAttribute("list");
//list=(java.util.List<User_Registration>)request.getParameter("list");
System.out.println(list.toString());
}catch(Exception e)
{
e.printStackTrace();
}
%>
<%=ForgotPasswordXml.xml(list)%>

any help would be appreciated.thnks

Sandhu Santhakumar · Accepted Answer · 2014-03-18T10:27:54.777

1

You can set the list in session as

request.getSession().setAttribute("list",list);

And in the next page retrieve the list as

@SuppressWarnings("unchecked")
List<Bean> list = (List<Bean>) request.getSession().getAttribute("list");

or

List<Bean> list = new ArrayList<Bean>();  
list.addAll(session.getAttribute("list"));

Note the type cast, it will avoid Type mismatch exception.

And if the list isn't needed further, remove it from the session as (optional)

request.getSession().removeAttribute("list");

edited Mar 18 '14 at 10:27

answered Mar 18 '14 at 10:14

Sandhu Santhakumar

1,678
1
13
24

i can't remove as i have to use this list to pass to a variable which will return me the string ,that i'll show as xml. – Divya Mar 18 '14 at 10:17
@A5l-lE5 removing the list from session depends on the nature of the application. Thats y I marked it as optional. – Sandhu Santhakumar Mar 18 '14 at 10:19
still its giving an error .unchecked cast from object to List – Divya Mar 18 '14 at 10:23
can you try putting @SuppressWarnings("unchecked") with List – Sandhu Santhakumar Mar 18 '14 at 10:27
i'm unable to put that warning ,as its type:safety check.also its giving java.lang.OutOfMemoryError: Java heap space exception.i tried to increase the heap size also but it didn't not works. – Divya Mar 18 '14 at 10:31
The method addAll(Collection extends User_Registration>) in the type List is not applicable for the arguments (Object) – Divya Mar 18 '14 at 10:45
Seems something is wrong with your `List` declaration , Can you post your model class – Santhosh Mar 18 '14 at 11:28
@sankrish i have modified the code how i m getting data in list. – Divya Mar 19 '14 at 09:58

score 0 · Answer 2 · answered Mar 19 '14 at 09:11

0

Send the whole List as one JSON string and rebuild the List using the JSON . You need to use JSONObject . The other thing you can do is , set List to Session and get back the List from the session and invalidate the Session if requires .

answered Mar 19 '14 at 09:11

Vivek Keshri

108
10

i dont want to use JSON as i m fetching data from the DB in to a list which i have to pass – Divya Mar 19 '14 at 09:14
in that case use RequestDispatcher and use forward method , there you can send the List . – Vivek Keshri Mar 19 '14 at 09:21
i have tried that but its not working m getting and error *unchecked cast from object to List* – Divya Mar 19 '14 at 09:23

how to pass a collection object in response.sendRedirect

2 Answers2