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

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!

Hi, Thanks for the quick reply. I've added @Service annotation to my EmployeeService class but error is still the same. — michal9225
These answers may help: stackoverflow.com/questions/16834333/… — Muizz Mahdy

Navnath Adsul Navnath Adsul · Accepted Answer · 2018-10-18T18:33:04

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

like

 @Autowired    
private EmployeeDAO employeeDAO;

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

1 Answers