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Servlet throws Unload Exception

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posted 12 years ago

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Please help me out,i started learning java few months ago.

SEVERE: Servlet EmailFormatServlet threw unload() exception
javax.servlet.ServletException: Servlet.destroy() for servlet EmailFormatServlet threw exception
at org.apache.catalina.core.StandardWrapper.unload(StandardWrapper.java:1413)
at org.apache.catalina.core.StandardWrapper.stop(StandardWrapper.java:1739)
at org.apache.catalina.core.StandardContext.stop(StandardContext.java:4601)
at org.apache.catalina.core.StandardContext.reload(StandardContext.java:3222)
at org.apache.catalina.manager.ManagerServlet.reload(ManagerServlet.java:943)
at org.apache.catalina.manager.ManagerServlet.doGet(ManagerServlet.java:361)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:199)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:558)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:859)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1555)
at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.NullPointerException
at EmailFormatServlet.destroy(EmailFormatServlet.java:27)
at org.apache.catalina.core.StandardWrapper.unload(StandardWrapper.java:1394)
... 23 more

Maneesh Godbole

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posted 12 years ago

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Obviously something is null on which you are invoking some method.
So you want to show us your EmailFormatServlet #destroy() ?

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Mohini Dhanaskar

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posted 12 years ago

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Sir,this is my servlet code.

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *
 * @author MOHINI
 */
public class EmailFormatServlet extends HttpServlet {

Connection con;
	PreparedStatement ps = null;

public void init(ServletConfig config) throws ServletException {
		con = DatabaseConnection.getConnection();
	}
        public void destroy(){
            try{
                ps.close();
                DatabaseConnection.close(con);
            }
            catch(SQLException e){
                e.printStackTrace();
            }
        }

@Override
    public void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
         try {
            java.sql.Statement stml = con.createStatement();
            ResultSet rset = stml.executeQuery("Select * from RegisterComplaint1");
             response.setContentType("text/html");
                PrintWriter out = response.getWriter();
                out.write("<html>");
                out.write("<head>");
                out.write("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\" />");
                out.write("<title>Untitled Document</title>");
                out.write("<style type=\"text/css\">");
                out.write("");
                out.write("</style>");
                out.write("</head>");
                out.write("<body bgcolor=\"#E0F8F7\">");
                out.write("<table width=\"600\" border=\"0\" align=\"center\" bordercolor=\"#FFFFFF\">");
                out.write("<tr>");
                out.write("<td align=\"center\" bgcolor=\"#FFFFFF\"><span class=\"style1\">Search by </span>  ");
                out.write("<select name=\"txtsearch\" >");
                out.write("<option value=\"customer-id\">Customer-ID</option>");
                out.write("<option value=\"area\">Area</option>");
                out.write("<option value=\"zone\">Zone</option>");
                out.write("<option value=\"complaint_type\">Complaint_Type</option>");
                out.write("<option value=\"date\">Date</option>");
                out.write("</select></td>");
                out.write("</tr>");
                out.write("<tr>");
                out.write("<td><table width=\"800\"  height=\"500\" border=\"1\" bordercolor=\"#666666\">");
                out.write("<tr>");
                out.write("<td width=\"119\" align=\"center\" valign=\"bottom\"><span class=\"style6\">Consumer ID</span></td>");
                out.write("<td width=\"118\" align=\"center\" valign=\"bottom\"><span class=\"style6\">Complain ID</span></td>");
                out.write("<td width=\"448\" align=\"center\" valign=\"bottom\"><span class=\"style6\">Complain Type</span></td>");
                out.write("<td width=\"87\" align=\"center\" valign=\"bottom\"><span class=\"style6\">Date</span></td>");
                out.write("</tr>");

while (rset.next()) {

out.print("<tr>");
               out.print("<td>"+rset.getObject(1)+"</td>");
               out.print("<td>"+rset.getObject(2)+"</td>");
               out.print("<td>"+rset.getObject(3)+"</td>");
               out.print("<td>"+rset.getObject(4)+"</td>");
               out.write("</tr>");
               out.print("<tr>        <td> </td>        <td> </td>        <td> </td>        <td> </td>      </tr>");
               out.print("<tr>        <td> </td>        <td> </td>        <td> </td>        <td> </td>      </tr>");
               out.print("<tr>        <td> </td>        <td> </td>        <td> </td>        <td> </td>      </tr>");
               out.print("<tr>        <td> </td>        <td> </td>        <td> </td>        <td> </td>      </tr>");
               out.print("<tr>        <td> </td>        <td> </td>        <td> </td>        <td> </td>      </tr>");
               out.print("<tr>        <td> </td>        <td> </td>        <td> </td>        <td> </td>      </tr>");
               out.print("<tr>        <td> </td>        <td> </td>        <td> </td>        <td> </td>      </tr>");
               out.print("<tr>        <td> </td>        <td> </td>        <td> </td>        <td> </td>      </tr>");
               out.print("<tr>        <td> </td>        <td> </td>        <td> </td>        <td> </td>      </tr>");

}
                out.write("</table></td>");
                out.write("</tr>");
                out.write(" <tr>");
                out.write("<td align=\"right\" bgcolor=\"#FFFFFF\"><input type=\"submit\" value=\"Previous\" name=\"btnprevious\" />  <input type=\"submit\" value=\"Next\" name=\"btnnext\" /></td>");
                out.write("</tr>");
                out.write("</table>");
                out.write("</body>");
                out.write("</html>");
                stml.close();
                System.out.println("Ok");
                } catch (Exception ex) {
                    System.out.println(ex.getMessage());
                }
            }

}

Maneesh Godbole

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posted 12 years ago

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In future, while posting code, please UseCodeTags I have added them this time for you. As you can see they make the code much more easier to read and understand

As per your stack trace the NullPointerException originated on line 27 of your code. viz.

That would indicate that the variable ps is null. Just put a null check before you invoke a method on it.

This is not really a servlet question. Moving to a more appropriate forum

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Campbell Ritchie

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. . . and we can see that[ttt ps [/tt]was previously initialised to null. You ought to initialise it to something useful and correct, then it will work

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