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  1. 10-04-2010, 08:04 PM #1
    karq
    karq is offline Member
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    Default textfield and nullpointerexception

    Hey everyone :)

    I'm trying to send some form data to a servelt, but everytime i hit submit button I get a nullpointerexeption.

    If i check the checkbox only and then hit submit, then it works, but if I insert data to textfields and hit submit, then I get a nullpointer.

    How to fix this?

    Heres my code:

    jsp page:
    Java Code: 
    <html>
<head>
<title>test</title>
</head>
<body>
<table border="1">
                <form action="SalaryFilter" method="post">
                <tr>
                    <td>
                        Palk
                    </td>
                </tr>
                <tr>
                    <td>
                       <input type="checkbox" name="palk" />
                        Kõrgeimad palgad
                    </td>
                </tr>
                <tr>
                    <td>
                        <input type="text" name="minSal" /> kuni <input type="text" name="maxSal"/>
                    </td>
                </tr>
                <tr>
                    <td>
                        <input type="submit" value="vaata" />
                    </td>
                </tr>
            </form>
            </table>
</body>
</html>
    Servlet code:
    Java Code: 
    package filter.filterServlets;

import filter.model.Employee;
import filter.sql.FilterManager;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class SalaryFilter extends HttpServlet {



    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        doPost(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {

        /*
         * Paremeters from EmployeeList.jsp
         */
        String checkboxState = request.getParameter("palk");
        String strMin = request.getParameter("minSal");
        String strMax = request.getParameter("maxSal");
        int min = 0;
        int max = 0;
        try{
            min = Integer.parseInt(strMin);
            max = Integer.parseInt(strMax);
        }catch(NumberFormatException e){
            e.printStackTrace();
        }
        /*
         * All filters
         */
        FilterManager filterManager = new FilterManager();

        /*
         * Filtered employee list
         */
        List<Employee> employeeList = null;

        if(checkboxState.equals("on")){
            employeeList = filterManager.getHighestSalary();
        }
        else{
            employeeList = filterManager.getSalaryMinMax(min, max);
        }
        request.setAttribute("list", employeeList);
        try{
            getServletConfig().getServletContext().
                    getRequestDispatcher("/EmployeeList.jsp").forward(request, response);
        }catch(ServletException e){
            System.err.println(e.getMessage());
        }catch(IOException e){
            System.err.println(e.getMessage());
        }


    }


}

    error code:
    Java Code: 
    java.lang.NullPointerException
	filter.filterServlets.SalaryFilter.doPost(SalaryFilter.java:58)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
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  2. 10-04-2010, 10:49 PM #2
    Norm's Avatar
    Norm
    Norm is offline Moderator
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    Default

    Have you located line 58? What variable used on that line is null?
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  3. 10-05-2010, 08:39 AM #3
    karq
    karq is offline Member
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    Default

    Quote Originally Posted by Norm View Post
    Have you located line 58? What variable used on that line is null?
    Thank you :)

    Found the problem

    fixed version:
    Java Code: 
    if(checkboxState != null){
            employeeList = filterManager.getHighestSalary();
        }
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  4. 10-05-2010, 10:11 AM #4
    Tolls
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    Default

    There you go.
    If you have a checkbox in a form, it will only be sent in the request if it is checked, otherwise (as you've seen) the getParameter() will return null.
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  5. 11-11-2010, 06:22 AM #5
    DarrylBurke's Avatar
    DarrylBurke
    DarrylBurke is offline Moderator
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    Default

    Spam reported.

    db
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