java - NumberFormatException: For input string: "xxxx" -

i'm trying display data on jsp page using jstl. i'm getting error numberformatexception: input string: "expense_id".

code

list expense = entitymanager         .getentitymanager()         .createnativequery(                 "select e.expense_id, format(e.expense_amount,2) expense_amount, date_format(e.expense_date, \"%y-%m-%d\") expense_date, e.expense_desc, e.payment_method, g.expense_group_name, c.company_name, e.comment wd_expense e "                         + "join wd_expense_group g on e.expense_group_id = g.expense_group_id "                         + "left join wd_company c on e.company_id = c.company_id")         .getresultlist();  // set request request.setattribute("expenses", expense);  // redirect expense_list.jsp util.redirect(request, response, "/web-inf/expense/expense_list.jsp"); 

jsp code

<tbody>     <c:foreach items="${requestscope.expenses}" var="expense">         <tr>             <td style="width: 5%;"><a                 href="expense_manage?expense_id=${expense.expense_id}"                 class="btn btn-outline btn-primary">edit</a>             </td>             <td>${expense.expense_desc}</td>             <td class="text-right">${expense.expense_amount}</td>             <td>${expense.expense_group_name}</td>             <td>${expense.comment}</td>             <td style="width: 10%;">                 <button type="button"                     onclick="confirmdelete('id=${expense.expense_id}','removeexpense')"                     class="btn btn-outline btn-danger">delete</button>             </td>         </tr>     </c:foreach> </tbody> 

error

exception :org.apache.jasper.jasperexception: exception occurred processing jsp page /web-inf/expense/expense_list.jsp @ line 47  44:                                         <c:foreach items="${requestscope.expenses}" var="expense"> 45:                                             <tr> 46:                                                 <td style="width: 5%;"><a 47:                                                     href="expense_manage?expense_id=${expense.expense_id}" 48:                                                     class="btn btn-outline btn-primary">edit</a> 49:                                                 </td> 50:                                                 <td>${expense.expense_desc}</td>   stacktrace: 

how can solve ?

you trying cast "expense_id" number. since "expense_id" string, cast throw numberformatexception. common problem doing (in pseudocode):

print "expense_id"; 

when want print variable value of expense_id. should instead (again pseudocode) like:

print expense_id; // no quotes 

on line 47, try changing:

<td style="width: 5%;"><a href="expense_manage?expense_id=${expense.expense_id}"> 

to:

<td style="width: 5%;"><a href="expense_manage?expense_id="+${expense.expense_id}>