Unable to convet Map in to JSONObject .....

Question

Hi, I have read many documentations and followed the procedure told by them....in order to convert a map in to JSONObject i wrote the following code..

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;



import net.sf.json.JSONArray;
import net.sf.json.JSONObject;






public class input extends HttpServlet {
 private static final long serialVersionUID = 1L;

 public input() {
  super();
 }
 protected void doGet(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {
  doPost(request,response);
 }
 protected void doPost(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {

  User user=new User();
  PrintWriter out = response.getWriter();
  System.out.println((user.getMap().get("firstname")));
  System.out.println((user.getMap().get("age")));


  out.print((user.getMap().get("firstname")));
  out.print((user.getMap().get("age")));
  Map map=user.getMap();
  JSONObject obj=JSONObject.fromObject(map);
  System.out.println(obj.toString());
 }
}

The values from the map are read correctly when i use normal methods...the problem is converting it in to JSONObject

and on executing Iam getting the following errors on stack trace.

Sep 2, 2010 8:23:52 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet input threw exception

java.lang.NoClassDefFoundError: org/apache/commons/collections/map/MultiKeyMap
 at net.sf.json.JsonConfig.(JsonConfig.java:56)
 at net.sf.json.JSONArray.fromObject(JSONArray.java:120)
 at input.doPost(input.java:46)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
 at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
 at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
 at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
 at java.lang.Thread.run(Thread.java:619)

i have included the follwing jar files in the path

commons-lang.jar commons-logging.jar commons-beanutils.jar ezmorph-1.0.1.jar json-lib-1.1-jdk15.jar commons-collection 3.1.jar

Kindly suggest me a way out....i tried implementing a generic pojo to JSONObject converter but its not working i tried using jacksons-mapper too still no luck ..please help me...