javascript - Validating form controls before inserting to database -

i want insert records database(mysql) before insertion want validate form fields whether filled users or not, must validate onclick of submit button , inserting records using annotation method related java file so, when trying insert records using spring annotation method , validating records in javascript gives me following error:

http status 500 - request processing failed; nested exception java.lang.numberformatexception: input string: ""

my javascript:

<script type="text/javascript">     function validatefields()     {         var c_name = document.formregisterclinic.ctl00$cphmaster$txtclinicname.value;         var p_no = document.formregisterclinic.ctl00$cphmaster$txtphone.value;         var st_address = document.formregisterclinic.ctl00$cphmaster$txtstreetaddress.value;         var state = document.formregisterclinic.ctl00$cphmaster$txtstate.value;         var city = document.formregisterclinic.ctl00$cphmaster$txtcity.value;}         var zip_code = document.formregisterclinic.ctl00$cphmaster$txtzipcode1.value;         var f_name = document.formregisterclinic.ctl00$cphmaster$txtcpfname.value;         var l_name = document.formregisterclinic.ctl00$cphmaster$txtcplname.value;         var email = document.formregisterclinic.ctl00$cphmaster$txtemail.value;         var cell_no = document.formregisterclinic.ctl00$cphmaster$txtcellphone.value;         var u_name = document.formregisterclinic.ctl00$cphmaster$txtusername.value;         var pass = document.formregisterclinic.ctl00$cphmaster$txtpassword.value;         var c_pass = document.formregisterclinic.ctl00$cphmaster$txtconfirmpassword.value;          if(c_name == "" || c_name == null)         {             alert("clinic name can't blank");             return false;         }         else if(p_no == "" || p_no == null)         {             alert("phone number can't blank");             return false;         }         else if(st_address == "" || st_address == null)         {             alert("street address can't blank");             return false;         }         else if(state == "" || state == null)         {             alert("state can't blank");             return false;         }         else if(city == "" || city == null)         {             alert("city can't blank");             return false;         }         else if(zip_code == "" || zip_code == null)         {             alert("zip code can't blank");             return false;         }         else if(f_name == "" || f_name == null)         {             alert("first name can't blank");             return false;         }         else if(l_name == "" || l_name == null)         {             alert("last name can't blank");             return false;         }         else if(email == "" || email == null)         {             alert("email can't blank");             return false;         }         else if(cell_no == "" || cell_no == null)         {             alert("cell number can't blank");             return false;         }         else if(u_name == "" || u_name == null)         {             alert("user name can't blank");             return false;         }         else if(pass == "" || pass == null)         {             alert("password can't blank");             return false;         }         else if(c_pass == "" || c_pass == null)         {             alert("confirm password can't blank");             return false;         } </script> 

my mapping method:

@requestmapping(value = "/registerclinic", method = requestmethod.post) public string registerclinicdbconnection(locale locale, model model, httpservletrequest req, httpservletresponse res)throws servletexception  {     string clinic_name = req.getparameter("ctl00$cphmaster$txtclinicname");     long phone_no = long.parselong(req.getparameter("ctl00$cphmaster$txtphone"));     string street_add = req.getparameter("ctl00$cphmaster$txtstreetaddress");     string state = req.getparameter("ctl00$cphmaster$txtstate");     string city = req.getparameter("ctl00$cphmaster$txtcity");     int zip_code = integer.valueof(req.getparameter("ctl00$cphmaster$txtzipcode1"));     string first_name =  req.getparameter("ctl00$cphmaster$txtcpfname");     string last_name =  req.getparameter("ctl00$cphmaster$txtcplname");     string email = req.getparameter("ctl00$cphmaster$txtemail");     long cell_phone = long.parselong(req.getparameter("ctl00$cphmaster$txtcellphone"));     string user_name = req.getparameter("ctl00$cphmaster$txtusername");     string password = req.getparameter("ctl00$cphmaster$txtpassword");     string c_password = req.getparameter("ctl00$cphmaster$txtconfirmpassword");       // inserting records register clinic making connection database.     string querytext = "insert registerclinic(clinicname,phone,streetadd,state,city,zipcode,firstname,lastname,email,cellphone,username,password) values('"+clinic_name+"','"+phone_no+"','"+street_add+"','"+state+"','"+city+"','"+zip_code+"','"+first_name+"','"+last_name+"','"+email+"','"+cell_phone+"','"+user_name+"','"+password+"')";     try     {         connection con = null;         class.forname("com.mysql.jdbc.driver");         con = (connection)drivermanager.getconnection("jdbc:mysql://localhost:3306/clinicmanagement","root","dipak");         statement stat = con.createstatement();         stat.executeupdate(querytext);         system.out.println("record has been inserted");         stat.close();         con.close();         return "success";     }catch(exception ea)     {          system.out.println("exception occured.."+ ea);         return "fail";     } } 

seems though don't have return true @ end of validatefields() method

try below:

function validatefields()     {         var c_name = document.formregisterclinic.ctl00$cphmaster$txtclinicname.value;         var p_no = document.formregisterclinic.ctl00$cphmaster$txtphone.value;         var st_address = document.formregisterclinic.ctl00$cphmaster$txtstreetaddress.value;         var state = document.formregisterclinic.ctl00$cphmaster$txtstate.value;         var city = document.formregisterclinic.ctl00$cphmaster$txtcity.value;}         var zip_code = document.formregisterclinic.ctl00$cphmaster$txtzipcode1.value;         var f_name = document.formregisterclinic.ctl00$cphmaster$txtcpfname.value;         var l_name = document.formregisterclinic.ctl00$cphmaster$txtcplname.value;         var email = document.formregisterclinic.ctl00$cphmaster$txtemail.value;         var cell_no = document.formregisterclinic.ctl00$cphmaster$txtcellphone.value;         var u_name = document.formregisterclinic.ctl00$cphmaster$txtusername.value;         var pass = document.formregisterclinic.ctl00$cphmaster$txtpassword.value;         var c_pass = document.formregisterclinic.ctl00$cphmaster$txtconfirmpassword.value;          if(c_name == "" || c_name == null)         {             alert("clinic name can't blank");             return false;         }         else if(p_no == "" || p_no == null)         {             alert("phone number can't blank");             return false;         }         else if(st_address == "" || st_address == null)         {             alert("street address can't blank");             return false;         }         else if(state == "" || state == null)         {             alert("state can't blank");             return false;         }         else if(city == "" || city == null)         {             alert("city can't blank");             return false;         }         else if(zip_code == "" || zip_code == null)         {             alert("zip code can't blank");             return false;         }         else if(f_name == "" || f_name == null)         {             alert("first name can't blank");             return false;         }         else if(l_name == "" || l_name == null)         {             alert("last name can't blank");             return false;         }         else if(email == "" || email == null)         {             alert("email can't blank");             return false;         }         else if(cell_no == "" || cell_no == null)         {             alert("cell number can't blank");             return false;         }         else if(u_name == "" || u_name == null)         {             alert("user name can't blank");             return false;         }         else if(pass == "" || pass == null)         {             alert("password can't blank");             return false;         }         else if(c_pass == "" || c_pass == null)         {             alert("confirm password can't blank");             return false;         }           return true;     }