insert update delete in Struts 2 but showing NullPointerException

StackOverflow https://stackoverflow.com/questions/23533541

Question

Here I come up with problem with Operation like update,delete and view so now insert is working but other operation like update, delete, view showing error like. Could some one can guide to go right direction? This what I have tried up to now

Error:

HTTP Status 500 - java.lang.NullPointerException

type Exception report

message java.lang.NullPointerException

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

exception

javax.servlet.ServletException: java.lang.NullPointerException
    org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:515)
    org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:419)
root cause

java.lang.NullPointerException
    Action.Testiue.view(Testiue.java:115)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:606)
    com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:404)
    com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:267)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:229)
    com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:221)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86)
    com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
    com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
    com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
    com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:150)
    org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:48)

struts.xml:

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">

<struts>
    <include file="struts-default.xml" />
    <package name="a" extends="struts-default">
        <action name="adduser" class="Action.Testiue" method="add">
            <result name="success">/insert.jsp</result>
            <result name="success">/ssuccess.jsp</result>
        </action>

        <action name="viewuser" class="Action.Testiue" method="view">
            <result name="success">/view.jsp</result>
            <result name="error">/error.jsp</result>

        </action>


        <action name="updateuser" class="Action.Testiue" method="update">
            <result name="success">/edit.jsp</result>
            <result name="error">/error.jsp</result>
        </action>

        <action name="deleteuser" class="Action.Testiue" method="delete">
            <result name="success">/dsuccess.jsp</result>
            <result name="error">/error.jsp</result>
        </action>

    </package>

</struts>

Web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <filter>
    <filter-name>struts2</filter-name>
    <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>struts2</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>


  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

TestIUE.java

package Action;

import com.opensymphony.xwork2.ActionSupport;

import dao.UserDao;
import dbBean.UseBean;

public class Testiue 
{

    private String Name;
    private String Password;
    private String EmailID;
    private String Phoneo;
    private int ID;

   public String getName()
    {
        return Name;
    }
    public void setName(String name)
    {
        Name = name;
    }
    public String getPassword()
    {
        return Password;
    }
    public void setPassword(String password)
    {
        Password = password;
    }
    public String getEmailID()
    {
        return EmailID;
    }
    public void setEmailID(String emailID)
    {
        EmailID = emailID;
    }
    public String getPhoneo()
    {
        return Phoneo;
    }
    public void setPhoneo(String phoneo)
    {
        Phoneo = phoneo;
    }
    public int getID()
    {
        return ID;
    }
    public void setID(int i)
    {
        ID = i;
    }
    @Override
    public String toString()
    {
        return "UseBean [id=" + ID + ", Name=" + Name+ ", Password=" + Password + ", EmailID=" + EmailID + ", Phoneo="+ Phoneo + "]";
    }  

    private UserDao dao;
    private UseBean bean;

    public String add()
    {
        dao=new UserDao();
       bean=new UseBean();
        System.out.println(getName()+""+getPassword()+""+getPhoneo()+""+getEmailID());
        bean.setID(ID);
        bean.setName(Name);
        bean.setPassword(Password);
        bean.setPhoneo(Phoneo);
        bean.setEmailID(EmailID);
        dao.addUser(bean);
        return ActionSupport.SUCCESS;

    }

    public String update()
    {

        dao=new UserDao();
        bean=new UseBean();
        //System.out.println(getName()+""+getPassword()+""+getPhoneo()+""+getEmailID());
        bean.setID(ID);
        bean.setName(Name);
        bean.setPassword(Password);
        bean.setPhoneo(Phoneo);
        bean.setEmailID(EmailID);
        dao.updateUser(bean);
        return ActionSupport.SUCCESS;

    }


    public String delete()
    {

        int userId =0;
        dao.deleteUser(userId);
        return ActionSupport.SUCCESS;
   }
    public String edit()
    {

        int userId =0;
        bean = dao.getUserById(userId);
        return ActionSupport.SUCCESS;
    }
    public String view()
    {

        dao.getAllUsers();
        return ActionSupport.SUCCESS;

    }

}

Index.jsp

<META HTTP-EQUIV="Refresh" CONTENT="0;URL=viewuser.action">

view.jsp;

<%@ taglib prefix="s" uri="/struts-tags"%>
<%@page import="java.util.*,dbBean.*,Dbconnect.*,java.util.*"%>

<a href="<s:url action="adduser.action"/>">Insert</a>

<table border=1>
    <thead>
        <tr>
        <th>Id</th>
        <th>Name</th>
        <th>password</th>
        <th>phoneno</th>
        <th>emailid</th>
        <th colspan=2>Action</th>
        </tr>
    </thead>
        <jsp:useBean id="users" class="java.util.ArrayList" scope="request" />
        <% for(int i = 0; i < users.size(); i+=1) 
        { 
            UseBean user = (UseBean)users.get(i);
        %>
        <tbody>
        <tr>
            <td><%= user.getID() %></td>
            <td><%= user.getName() %></td>
            <td><%= user.getPassword() %></td>
            <td><%= user.getEmailID() %></td>
            <td><%= user.getPhoneo() %></td>
            <td><a href="<s:url action="updateuser.action"/>">Update</a></td>
            <td><a href="<s:url action="delete.action"/>">Delete</a></td>

            </tr>

<%      
}
%>
</tbody>
 </table>

edit.jsp:

<%@ page language="java" contentType="text/html; charset=UTF-8" 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>Insert title here</title>
</head>
<body>
<form action="updateuser">

        id:<input type="text" name="ID" ><br/>
        Name:<input type="text" name="Name" ><br/>
        Password:<input type="text" name="password" ><br/>
        phoneno:<input type="text" name="Phoneo" ><br/>
        Emailid:<input type="text" name="Emailid" >  <br/> 

         <input type="submit" value="Submit" />
    </form>     
</body>
</html>

UserDao.java

package dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import dbBean.UseBean;
import Dbconnect.*;

public class UserDao
{

    private Connection conn;

    public UserDao()
    {
        conn=Dbconnect.getConnection();
    }
    public void addUser(UseBean bean)
    {
        try
        {
            String sql="insert into senthil (name,pass,phoneno,emailid) values(?,?,?,?)";
            PreparedStatement ps=conn.prepareStatement(sql);    
            ps.setString(1,bean.getName());
            ps.setString(2,bean.getPassword());
            ps.setString(3,bean.getPhoneo());
            ps.setString(4,bean.getEmailID());
            ps.executeUpdate();

        }
        catch (Exception e)
        {
            // TODO: handle exception
        }
    }
    public void deleteUser(int userId)
    {
        try
        {
            PreparedStatement ps = conn.prepareStatement("delete from senthil where id=?");
            // Parameters start with 1
            ps.setInt(1, userId);
            ps.executeUpdate();

        } catch (SQLException e)
        {
            e.printStackTrace();
        }
    }

    public void updateUser(UseBean bean)
    {
        try
        {
            PreparedStatement preparedStatement = conn.prepareStatement("update senthil set name=?, pass=?, phoneno=?, emailid=?"+ "where id=?");
            // Parameters start with 1
            preparedStatement.setString(1, bean.getName());
            preparedStatement.setString(2, bean.getPassword());
            preparedStatement.setString(3, bean.getPhoneo());
            preparedStatement.setString(4, bean.getEmailID());
            preparedStatement.setInt(5, bean.getID());
            preparedStatement.executeUpdate();

        } 
        catch (SQLException e)
        {
            e.printStackTrace();
        }
    }



    public List<UseBean> getAllUsers()
    {
        List<UseBean> users = new ArrayList<UseBean>();
        try
        {
            Statement statement = conn.createStatement();
            ResultSet rs = statement.executeQuery("select * from senthil");
            while (rs.next())
            {
                UseBean user = new UseBean();
                user.setID(rs.getInt("id"));
                user.setName(rs.getString("name"));
                user.setPassword(rs.getString("pass"));
                user.setPhoneo(rs.getString("phoneno"));
                user.setEmailID(rs.getString("emailid"));
                users.add(user);
            }
        } 
        catch (SQLException e)
        {
            e.printStackTrace();
        }

        return users;
    }


    public UseBean getUserById(int userId)
    {
        UseBean user = new UseBean();
        try
        {
            PreparedStatement preparedStatement = conn.prepareStatement("select * from senthil where id=?");
            preparedStatement.setInt(1, userId);
            ResultSet rs = preparedStatement.executeQuery();

            if (rs.next())
            {
                user.setID(rs.getInt("id"));
                user.setName(rs.getString("name"));
                user.setPassword(rs.getString("pass"));
                user.setPhoneo(rs.getString("phoneno"));
                user.setEmailID(rs.getString("emailid"));
            }
        } catch (SQLException e)
        {
            e.printStackTrace();
        }

        return user;
    }       
}
Was it helpful?

Solution

In the JSP the users should be available to the request scope.

public String view() {
  UserDao userDao = new UserDao();
  List<UseBean> users = userDao.getAllUsers();
  ServletActionContext.getRequest().setAttribute("users", users);
  return Action.SUCCESS;
}

public String update() {
  UserDao dao = new UserDao();
  UseBean bean=new UseBean();
  HttpServletRequest request ServletActionContext.getRequest();
  bean.setID(request.getParameter("ID");
  bean.setName(request.getParameter("Name");
  bean.setPassword(request.getParameter("Password");
  bean.setPhoneo(request.getParameter("Phoneo");
  bean.setEmailID(request.getParameter("EmailID");
  //System.out.println(getName()+""+getPassword()+""+getPhoneo()+""+getEmailID());
  dao.updateUser(bean);
  return Action.SUCCESS;

}

public String delete() {
  HttpServletRequest request ServletActionContext.getRequest();
  int userId = request.getParameter("ID");
  dao.deleteUser(userId);
  return Action.SUCCESS;
}

for delete action

<a href="<s:url action="delete"><s:param name='ID'><%=user.getID()%></s:param></s:url>">Delete</a>

OTHER TIPS

Inside view method you haven't initialized the dao object(i.e reference is null), add the following code :

In TestIUE.java add one more member variable : 

  List<UseBean> users = new ArrayList<UseBean>();

Also add Accessor method : 

  public List<UseBean> getUsers()
  {
     return users;
  }

Now modify your view method as follows : 

  public String view()
  {
    dao = new UseDao();
    users = dao.getAllUsers();
    return ActionSupport.SUCCESS;

  }
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