java - nullpointer exception when initializing a class in servlet -

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 class mstleastcountedit {     mstleastcount reff;     httpservletrequest request;     httpservletresponse response;     string msg = "";     string lcdesc="";     int = 0;     int noofrows = 0;     httpsession session=request.getsession(true);     integer ccode=(integer) session.getattribute("companycode");      void updateedit(mstleastcount reff,httpservletrequest request, httpservletresponse response, int k)     throws servletexception,ioexception,illegalstateexception {         int j = k;         this.reff=reff;         this.request=request;         this.response=response;         try{              noofrows = integer.parseint(request.getparameter("noofrows"));             string chkboxval="";             for(i=j;i<=noofrows;i++) {                 if((request.getparameter("chk_select"+i))==null) {                     chkboxval="notticked";                 }//if checked closed                 else {                     chkboxval=request.getparameter("chk_select"+i);                     if(chkboxval.equals("ticked")) {                         string lcid=request.getparameter("txtlcid"+i);                         string lcdesc=request.getparameter("txtlcdesc"+i);                                                           lcdesc=lcdesc.trim();                         string rec_status=request.getparameter("recstatus"+i);                         statement st=reff.con.createstatement();                         string qu="xxxxxxxxxxxxxxxxx";                         st.executeupdate(qu);                     }//if chkbox closed                 }//else checked closed                 //j+=1;             }//for loop closed         } catch(sqlexception sql) {             request.setattribute("error", ge+" general e exception");             reff.getservletconfig().getservletcontext().getrequestdispatcher("/errjsp.jsp").forward(request,response);         } catch(exception ge) {             request.setattribute("error", ge+" general e exception");             reff.getservletconfig().getservletcontext().getrequestdispatcher("/errjsp.jsp").forward(request,response);         }                    resultset rs1 = null;         try {             statement st1 = reff.con.createstatement();             rs1 = st1.executequery("select * xxxx");             resultsetmetadata rsm = rs1.getmetadata();             int col_count = rsm.getcolumncount();             vector vrow = new vector();             while(rs1.next()) {                 vector vcol = new vector();                 for(int i=1;i<=col_count;i++) {                     vcol.addelement(rs1.getobject(i));                 }                 vrow.addelement(vcol);             } //while loop closed             request.setattribute("vrow",vrow);             request.setattribute("msg",msg);             reff.getservletconfig().getservletcontext().getrequestdispatcher("/xxx.jsp").forward(request,response);         }catch(sqlexception sqldel){}         return ;     } }

the servlet trying call class this

mstleastcountedit ref1 = new mstleastcountedit();

and throws nullpointer exception. still sloppy on class , , old code developed 10 years back, ??

glancing through code...

httpservletrequest request;  [...]  httpsession session=request.getsession(true); integer ccode=(integer) session.getattribute("companycode");

this line should throw exception. request has not been assign , null, hence npe.

a servlet typically served between request , sessions. handling multiple requests @ once. therefore, not store requests, sessions , related data within servlet instance.

(as matter of practice: make fields private , possible final, add spaces more conventionally, use camel caps variable names (for instance companycode) , don't abbreviate words particularly if become meaningless.)


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