无法在 Servlet 中将 Int 转换为 String

Question

im tried to make a method for insert data, But an error in parsing value. this error seems to be in the process convert int to string in my insert method, and show this error :

type Exception report

message null

description The server encountered an internal error that prevented it from fulfilling this request.

exception

java.lang.NumberFormatException: null
    java.lang.Integer.parseInt(Integer.java:542)
    java.lang.Integer.parseInt(Integer.java:615)
    servlet.JobServlet.insert(JobServlet.java:137)
    servlet.JobServlet.doGet(JobServlet.java:85)
    servlet.JobServlet.doPost(JobServlet.java:123)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)

note The full stack trace of the root cause is available in the Apache Tomcat/8.0.27 logs.

help me fix it.

this my insert method on servlet :

private void insert(HttpServletRequest request, HttpServletResponse response)
            throws SQLException, IOException {
        String id = request.getParameter("idJob");
        String title = request.getParameter("titleJob");
        int min = Integer.parseInt(request.getParameter("minSalary"));
        int max = Integer.parseInt(request.getParameter("maxSalary"));
        dao.save(new Job(id, title, min, max));
        response.sendRedirect("jobServlet?action=list");
    }

and this my jsp code :

    <div class="card-body card-block">
                                    <form action="jobServlet?action=insert" method="post" class="form-vertical">
                                        <div class="row form-group">
                                            <div class="col-12 col-md-9">
                                                <input type="text" id="idJob" name="idJob" placeholder="Enter Job Id..." class="form-control">
                                            </div>
                                            <div class="col-12 col-md-9">
                                                <input type="text" id="titleJob" name="titleJob" placeholder="Enter Job Title..." class="form-control">
                                            </div>
                                            <div class="col-12 col-md-9">
                                                <input type="text" id="minSalary" name="minSalary" placeholder="Enter Minimal Salary..." class="form-control">
                                            </div>
                                            <div class="col-12 col-md-9">
                                                <input type="text" id="maxSalary" name="maxSalary" placeholder="Enter Maximal Salary..." class="form-control">
                                            </div>
                                        </div>
                                        <input type="submit" name="submit" value="Save" class="btn btn-primary btn-sm"/>

i tried this but still didn't work :

private void insert(HttpServletRequest request, HttpServletResponse response)
                throws SQLException, IOException {
            String id = request.getParameter("idJob");
            String title = request.getParameter("titleJob");
            String min = request.getParameter("minSalary");
            String max = request.getParameter("maxSalary");
            dao.save(new Job(id, title, Integer.parseInt(min),Integer.parseInt(max)));
            response.sendRedirect("jobServlet?action=list");
        }

Answer 1

inspect your request (can easily do if you are using a browser) and see if the maxSalary and minSalary are passed. One of them is null.

Also, if you are using html5, theres no need to use text as your input type. Simply use number and you will get an int.

Furthermore, whereever you use Integer.parseInt(), catch the number format exception.