Spring CRUD App: Servlet.service() for servlet [dispatcherServlet] : java.lang.NullPointerException] - spring

Question

I've a problem to get employees data from mySQL db. According to logs there is a problem at line: 36 in my EmployeeServiceImpl.listEmployess metod.
Logs:
2018-10-18 16:07:42.871 ERROR 1504 --- [nio-8090-exec-4] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause
java.lang.NullPointerException: null
at com.project.service.EmployeeServiceImpl.listEmployess(EmployeeServiceImpl.java:36) ~[classes/:na]
com.project.service.EmployeeServiceImpl$$FastClassBySpringCGLIB$$c7d76ecc.invoke() ~[classes/:na]
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) ~[spring-core-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:746) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:294) ~[spring-tx-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98) ~[spring-tx-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at com.project.service.EmployeeServiceImpl$$EnhancerBySpringCGLIB$$1390ca06.listEmployess() ~[classes/:na]
at com.project.controller.EmployeeController.listEmployess(EmployeeController.java:34) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_161]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_161]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_161]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_161]
EmployeeServiceImpl:
package com.project.service;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import com.project.dao.EmployeeDAO;
import com.project.entity.TEmployee;
#Service("employeeService")
public class EmployeeServiceImpl implements EmployeeService {
private EmployeeDAO employeeDAO;
public void setEmployeeDAO(EmployeeDAO employeeDAO) {
this.employeeDAO = employeeDAO;
}
#Override
#Transactional
public void addEmployee(TEmployee p) {
this.employeeDAO.addEmployee(p);
}
#Override
#Transactional
public void updateEmployee(TEmployee p) {
this.employeeDAO.updateEmployee(p);
}
#Override
#Transactional
public List<TEmployee> listEmployess() {
return this.employeeDAO.listEmployess();
}
#Override
#Transactional
public TEmployee getEmployeeById(int employee_id) {
return this.employeeDAO.getEmployeeById(employee_id);
}
#Override
#Transactional
public void removeEmployee(int employee_id) {
this.employeeDAO.removeEmployee(employee_id);
}
}
EmployeeService:
package com.project.service;
import java.util.List;
import org.springframework.context.annotation.ComponentScan;
import com.project.entity.TEmployee;
#ComponentScan(basePackages= {"com.project.*"})
public interface EmployeeService {
public void addEmployee(TEmployee p);
public void updateEmployee(TEmployee p);
public List<TEmployee> listEmployess();
public TEmployee getEmployeeById(int id);
public void removeEmployee(int id);
}
EmployeeDAO:
package com.project.dao;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.ComponentScan;
import com.project.entity.TEmployee;
#ComponentScan(basePackages= {"com.project.*"})
public interface EmployeeDAO {
public void addEmployee(TEmployee p);
public void updateEmployee(TEmployee p);
public List<TEmployee> listEmployess();
public TEmployee getEmployeeById(int employee_id);
public void removeEmployee(int employee_id);
}
EmployeeDAOImpl:
package com.project.dao;
import java.util.List;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import com.project.entity.TEmployee;
#Repository
public class EmployeeDAOImpl implements EmployeeDAO {
private static final Logger logger = LoggerFactory.getLogger(EmployeeDAOImpl.class);
private SessionFactory sessionFactory;
public void setSessionFactory(SessionFactory sf){
this.sessionFactory = sf;
}
#Override
public void addEmployee(TEmployee p) {
Session session = this.sessionFactory.getCurrentSession();
session.persist(p);
logger.info("TEmployee saved successfully, TEmployee Details="+p);
}
#Override
public void updateEmployee(TEmployee p) {
Session session = this.sessionFactory.getCurrentSession();
session.update(p);
logger.info("TEmployee updated successfully, TEmployee Details="+p);
}
#SuppressWarnings("unchecked")
#Override
public List<TEmployee> listEmployess() {
Session session = this.sessionFactory.getCurrentSession();
List<TEmployee> EmployessList = session.createQuery("from TEmployee").list();
for(TEmployee p : EmployessList){
logger.info("TEmployee List::"+p);
}
return EmployessList;
}
#Override
public TEmployee getEmployeeById(int employee_id) {
Session session = this.sessionFactory.getCurrentSession();
TEmployee p = (TEmployee) session.load(TEmployee.class, new Integer(employee_id));
logger.info("TEmployee loaded successfully, TEmployee details="+p);
return p;
}
#Override
public void removeEmployee(int employee_id) {
Session session = this.sessionFactory.getCurrentSession();
TEmployee p = (TEmployee) session.load(TEmployee.class, new Integer(employee_id));
if(null != p){
session.delete(p);
}
logger.info("TEmployee deleted successfully, TEmployee details="+p);
}
}
And EmployeeController:
package com.project.controller;
import javax.annotation.Resource;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import com.project.entity.TEmployee;
import com.project.service.EmployeeService;
#ComponentScan(basePackages= {"com.project.*"})
#Controller
public class EmployeeController {
#Resource(name = "employeeService")
private EmployeeService employeeService;
#Autowired(required=true)
#Qualifier(value="employeeService")
public void setEmployeeService(EmployeeService ps){
this.employeeService = ps;
}
#RequestMapping(value = "/employess", method = RequestMethod.GET)
public String listEmployess(Model model) {
model.addAttribute("employee", new TEmployee());
model.addAttribute("listEmployess", this.employeeService.listEmployess());
return "employee";
}
//For add and update person both
#RequestMapping(value= "/employee/add", method = RequestMethod.POST)
public String addEmployee(#ModelAttribute("employee") TEmployee p){
if(p.getEmployeeID() == 0){
//new person, add it
this.employeeService.addEmployee(p);
}else{
//existing person, call update
this.employeeService.updateEmployee(p);
}
return "redirect:/employess";
}
#RequestMapping("/remove/{employee_id}")
public String removeEmployee(#PathVariable("employee_id") int employee_id){
this.employeeService.removeEmployee(employee_id);
return "redirect:/employess";
}
#RequestMapping("/edit/{employee_id}")
public String editEmployee(#PathVariable("employee_id") int employee_id, Model model){
model.addAttribute("employee", this.employeeService.getEmployeeById(employee_id));
model.addAttribute("listEmployess", this.employeeService.listEmployess());
return "employee";
}
}
So, according to logs there is a NPE returning from this line:
return this.employeeDAO.listEmployess();
Do you have any idea what could be wrong here?
Thanks in advance!

Answer 1

Hi instead of setter method use Autowired annotation on dependency private EmployeeDAO employeeDAO;
like
#Autowired
private EmployeeDAO employeeDAO;