NumberFormatException：对于输入字符串：“ xxxx”

Question

I'm trying to display data on jsp page using jstl. but i'm getting error as NumberFormatException: For input string: "expense_id" .

Code

List expense = entityManager
        .getEntityManager()
        .createNativeQuery(
                "SELECT e.expense_id, format(e.expense_amount,2) as expense_amount, DATE_FORMAT(e.expense_date, \"%Y-%m-%d\") as expense_date, e.expense_desc, e.payment_method, g.expense_group_name, c.company_name, e.comment FROM 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 to request
request.setAttribute("expenses", expense);

// redirect to 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: An exception occurred processing JSP page /WEB-INF/expense/expense_list.jsp at 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 i solve this ?

Answer 1

You are trying to cast "expense_id" to a number. Since "expense_id" is a String, this cast will throw a NumberFormatException. The most common problem is doing (in pseudocode):

print "expense_id";

when you actually want to print the variable value of expense_id. This should instead (again pseudocode) look 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}>