java如何从下拉列表中获取所选号码？

Question

我的问题是获取我在请求中尝试的所选号码。getParameter（“numberoft”）； 它显示NumberFormatException。 组织。阿帕奇。贾斯珀。JaspereException:在第[18]行处理[/html/payment.jsp]时发生异常

15:     <%! Integer num = 0; %>
16:     <%
17:     ImageSource imgPath = (ImageSource)request.getAttribute("path");
18:     num = Integer.parseInt(request.getParameter("numberoft"));
19:     %>
20:       <img src="<%=imgPath.getImagePath()%>" alt="product"> 
21:       <div class="content">


Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:626)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:515)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
com.shiv.servlets.MoviesServlet.doGet(MoviesServlet.java:28)
javax.servlet.http.HttpServlet.service(HttpServlet.java:626)
javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

Root Cause
java.lang.NumberFormatException: null
java.lang.Integer.parseInt(Unknown Source)
java.lang.Integer.parseInt(Unknown Source)
org.apache.jsp.html.payment_jsp._jspService(payment_jsp.java:138)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:71)
javax.servlet.http.HttpServlet.service(HttpServlet.java:733)



<div class="ticket">
      <div class="number">
      <label>Tickets</label>
            <select name="numberoft">
                <option value="1">1</option>
                <option value="2">2</option>
                <option value="3">3</option>
                <option value="4">4</option>
                <option value="5">5</option>
                <option value="6">6</option>
                <option value="7">7</option>
                <option value="8">8</option>
                <option value="9">9</option>
                <option value="10">10</option>
            </select>
     </div>
</div>

In this JSP code I am trying to fetch selected number by get Parameter 
getting Number Format Exception

[1]: https://i.stack.imgur.com/wfanr.png