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JDBC and Relational Databases
connectio null problem
Samanthi perera
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posted 13 years ago
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this is my
jsp
class
<%@page contentType="text/html" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>JSP Page</title> </head> <body> <form method="post" action="Test"> Name <input type="text" name="name" size="5"></br> Age <input type="text" name="age" size="5"></br> Address <input type="text" name="address" size="5"></br> <input type="submit" name="submit"> </form> </body> </html>
this is my
servlet
part of code
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { try { processRequest(request, response); } catch (SQLException ex) { Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex); } } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { PrintWriter out = response.getWriter(); Connection connection=null; try { PrintWriter pw = response.getWriter(); pw.write("HIIIIIIIIIIIIIII"); MyConnection con=new MyConnection(); connection=con.getConnection(); if(connection==null){ pw.write("connection is NUUUUUUUUUUUUUUUUUUUUUUUUUUUUULLL"); } Statement st=connection.createStatement(); //String s="Insert into User values("+"'sudu'"+","+"'panadura'"+25+")"; ResultSet res=st.executeQuery("Select * from User"); while(res.next()){ int i = res.getInt("name"); String s = res.getString("Emp_name"); System.out.println(i + "\t\t" + s); } // st.executeUpdate(s); } catch(Exception e){ e.printStackTrace(); } finally { out.close(); } }
this is my connection class
/* * To change this template, choose Tools | Templates * and open the template in the editor. */ package jspServlet; import java.sql.Connection; import java.sql.DriverManager; public class MyConnection { public Connection getConnection(){ Connection con = null; String url ="jdbc:mysql://localhost:3306/"; String dbName ="jdbctutorial"; String driverName ="com.mysql.jdbc.Driver"; String userName ="root"; String password =""; try{ Class.forName(driverName).newInstance(); con = DriverManager.getConnection(url+dbName,userName,password); }catch(Exception e){ } return con; } }
But is prints Coeection is null
Paul Sturrock
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}catch(Exception e){ }
Your code seems to be written in a way to be deliberately unhelpful! Exception stack traces contain a wealth of information about what is going wrong. Print the stack trace -
you should
get an idea what could be happening.
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Samanthi perera
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this is the error
classLoader = WebappClassLoader delegate: true repositories: /WEB-INF/classes/ ----------> Parent Classloader: EJBClassLoader : urlSet = [] doneCalled = false Parent -> java.net.URLClassLoader@c52200 SharedSecrets.getJavaNetAccess()=java.net.URLClassLoader$7@152c4ce Cannot load jspServlet.NewServlet reason : jspServlet.NewServlet java.lang.ClassNotFoundException: jspServlet.NewServlet at com.sun.enterprise.loader.EJBClassLoader.findClassData(EJBClassLoader.java:738) at com.sun.enterprise.loader.EJBClassLoader.findClass(EJBClassLoader.java:628) at java.lang.ClassLoader.loadClass(ClassLoader.java:306) at java.lang.ClassLoader.loadClass(ClassLoader.java:251) at com.sun.enterprise.deployment.annotation.impl.ModuleScanner.getElements(ModuleScanner.java:186) at com.sun.enterprise.deployment.archivist.Archivist.processAnnotations(Archivist.java:405) at com.sun.enterprise.deployment.archivist.Archivist.readAnnotations(Archivist.java:346) at com.sun.enterprise.deployment.archivist.Archivist.readDeploymentDescriptors(Archivist.java:318) at com.sun.enterprise.deployment.archivist.Archivist.open(Archivist.java:213) at com.sun.enterprise.deployment.archivist.ApplicationArchivist.openArchive(ApplicationArchivist.java:813) at com.sun.enterprise.deployment.archivist.ApplicationArchivist.openArchive(ApplicationArchivist.java:794) at com.sun.enterprise.deployment.backend.Deployer.loadDescriptors(Deployer.java:365) at com.sun.enterprise.deployment.backend.ModuleDeployer.loadDescriptors(ModuleDeployer.java:426) at com.sun.enterprise.deployment.backend.WebModuleDeployer.deploy(WebModuleDeployer.java:160) at com.sun.enterprise.deployment.backend.ModuleDeployer.doRequestFinish(ModuleDeployer.java:182) at com.sun.enterprise.deployment.phasing.J2EECPhase.runPhase(J2EECPhase.java:208) at com.sun.enterprise.deployment.phasing.DeploymentPhase.executePhase(DeploymentPhase.java:108) at com.sun.enterprise.deployment.phasing.PEDeploymentService.executePhases(PEDeploymentService.java:966) at com.sun.enterprise.deployment.phasing.PEDeploymentService.deploy(PEDeploymentService.java:283) at com.sun.enterprise.deployment.phasing.PEDeploymentService.deploy(PEDeploymentService.java:835) at com.sun.enterprise.management.deploy.DeployThread.deploy(DeployThread.java:187) at com.sun.enterprise.management.deploy.DeployThread.run(DeployThread.java:225) Cannot load jspServlet.NewServlet reason : jspServlet.NewServlet java.lang.ClassNotFoundException: jspServlet.NewServlet at com.sun.enterprise.loader.EJBClassLoader.findClassData(EJBClassLoader.java:715) at com.sun.enterprise.loader.EJBClassLoader.findClass(EJBClassLoader.java:628) at java.lang.ClassLoader.loadClass(ClassLoader.java:306) at java.lang.ClassLoader.loadClass(ClassLoader.java:251) at com.sun.enterprise.deployment.annotation.impl.ModuleScanner.getElements(ModuleScanner.java:186) at com.sun.enterprise.deployment.annotation.impl.AnnotationProcessorImpl.process(AnnotationProcessorImpl.java:127) at com.sun.enterprise.deployment.archivist.Archivist.processAnnotations(Archivist.java:445) at com.sun.enterprise.deployment.archivist.Archivist.readAnnotations(Archivist.java:346) at com.sun.enterprise.deployment.archivist.Archivist.readDeploymentDescriptors(Archivist.java:318) at com.sun.enterprise.deployment.archivist.Archivist.open(Archivist.java:213) at com.sun.enterprise.deployment.archivist.ApplicationArchivist.openArchive(ApplicationArchivist.java:813) at com.sun.enterprise.deployment.archivist.ApplicationArchivist.openArchive(ApplicationArchivist.java:794) at com.sun.enterprise.deployment.backend.Deployer.loadDescriptors(Deployer.java:365) at com.sun.enterprise.deployment.backend.ModuleDeployer.loadDescriptors(ModuleDeployer.java:426) at com.sun.enterprise.deployment.backend.WebModuleDeployer.deploy(WebModuleDeployer.java:160) at com.sun.enterprise.deployment.backend.ModuleDeployer.doRequestFinish(ModuleDeployer.java:182) at com.sun.enterprise.deployment.phasing.J2EECPhase.runPhase(J2EECPhase.java:208) at com.sun.enterprise.deployment.phasing.DeploymentPhase.executePhase(DeploymentPhase.java:108) at com.sun.enterprise.deployment.phasing.PEDeploymentService.executePhases(PEDeploymentService.java:966) at com.sun.enterprise.deployment.phasing.PEDeploymentService.deploy(PEDeploymentService.java:283) at com.sun.enterprise.deployment.phasing.PEDeploymentService.deploy(PEDeploymentService.java:835) at com.sun.enterprise.management.deploy.DeployThread.deploy(DeployThread.java:187) at com.sun.enterprise.management.deploy.DeployThread.run(DeployThread.java:225) deployed with moduleid = CRUD classLoader = WebappClassLoader delegate: true repositories: /WEB-INF/classes/ ----------> Parent Classloader: EJBClassLoader : urlSet = [] doneCalled = false Parent -> java.net.URLClassLoader@c52200 SharedSecrets.getJavaNetAccess()=java.net.URLClassLoader$7@152c4ce deployed with moduleid = CRUD classLoader = WebappClassLoader delegate: true repositories: /WEB-INF/classes/ ----------> Parent Classloader: EJBClassLoader : urlSet = [] doneCalled = false Parent -> java.net.URLClassLoader@c52200 SharedSecrets.getJavaNetAccess()=java.net.URLClassLoader$7@152c4ce deployed with moduleid = CRUD java.lang.NullPointerException at jspServlet.Test.doPost(Test.java:59) at javax.servlet.http.HttpServlet.service(HttpServlet.java:754) at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) at org.apache.catalina.core.ApplicationFilterChain.servletService(ApplicationFilterChain.java:427) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:315) at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:287) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:218) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593) at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:94) at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:98) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:222) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:587) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:1096) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:166) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:587) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:1096) at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:288) at com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.invokeAdapter(DefaultProcessorTask.java:647) at com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.doProcess(DefaultProcessorTask.java:579) at com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.process(DefaultProcessorTask.java:831) at com.sun.enterprise.web.connector.grizzly.DefaultReadTask.executeProcessorTask(DefaultReadTask.java:341) at com.sun.enterprise.web.connector.grizzly.DefaultReadTask.doTask(DefaultReadTask.java:263) at com.sun.enterprise.web.connector.grizzly.DefaultReadTask.doTask(DefaultReadTask.java:214) at com.sun.enterprise.web.connector.grizzly.TaskBase.run(TaskBase.java:265) at com.sun.enterprise.web.connector.grizzly.ssl.SSLWorkerThread.run(SSLWorkerThread.java:106)
Paul Sturrock
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Well, though that stack trace certainly looks bad it is not comming from your connection code. Did you print the stack trace from there?
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Samanthi perera
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java.lang.NullPointerException at jspServlet.Test.doPost(Test.java:59) at javax.servlet.http.HttpServlet.service(HttpServlet.java:754) at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) at org.apache.catalina.core.ApplicationFilterChain.servletService(ApplicationFilterChain.java:427) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:315) at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:287) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:218) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593) at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:94) at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:98) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:222) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:587) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:1096) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:166) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:587) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:1096) at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:288) at com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.invokeAdapter(DefaultProcessorTask.java:647) at com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.doProcess(DefaultProcessorTask.java:579) at com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.process(DefaultProcessorTask.java:831) at com.sun.enterprise.web.connector.grizzly.DefaultReadTask.executeProcessorTask(DefaultReadTask.java:341) at com.sun.enterprise.web.connector.grizzly.DefaultReadTask.doTask(DefaultReadTask.java:263) at com.sun.enterprise.web.connector.grizzly.DefaultReadTask.doTask(DefaultReadTask.java:214) at com.sun.enterprise.web.connector.grizzly.TaskBase.run(TaskBase.java:265) at com.sun.enterprise.web.connector.grizzly.ssl.SSLWorkerThread.run(SSLWorkerThread.java:106)
Swastik Dey
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posted 13 years ago
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You probably need a stackTrace in getConnection method in MyConnection class to know the reason.
Swastik
Samanthi perera
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posted 13 years ago
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Thanks.
I didn't add the mysql connector jar.
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