@Autowired not working

[Alejandro Barrero]

I have a simple test class in Spring

package com.javaspringclub.test;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;

import com.javaspringclub.entity.User;
import com.javaspringclub.service.UserService;

public class Test {
	@Autowired
	private UserService userService;

	public static void main(String[] args) {
		Test test = new Test();
		List<User> userList = test.userService.getAllUsers();
		userList.forEach(user->System.out.println(user));
	}
}

But I am getting userService null in line
List<User> userList = test.userService.getAllUsers();
I also have

package com.javaspringclub.service;

import java.util.List;
import com.javaspringclub.entity.User;

public interface UserService {
	public List<User> getAllUsers();
	public User getUserById(Long id);
	public boolean saveUser(User user);
	public boolean deleteUserById(Long id);
}

[Rob Spoor]

Unless I'm missing something, you never specified how the UserService should be made available for autowiring. Unless it extends (Crud)Repository or there is an @Component implementation or a @Bean provider, this interface is no different from any other interface.

Also, autowiring only works if you let Spring create the instances. The way you're using Test, it's a simple POJO where nothing will get autowired.

[M Khalid]

UserService is an interface. Try to implement it with a Class and using "Service" annotation and override the method you are calling. Or else You should extend CRUD/PagingAndSorting Repository.
Service Annotation

[Alejandro Barrero]

My apologies.

package com.javaspringclub.repository;

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

import com.javaspringclub.entity.User;

@Repository
public interface UserRepository extends CrudRepository<User, Long>{
	
}

package com.javaspringclub.service;

import java.util.ArrayList;
import java.util.List;

import javax.transaction.Transactional;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.javaspringclub.entity.User;
import com.javaspringclub.repository.UserRepository;

@Service
@Transactional
public class UserServiceImpl implements UserService {

		// Implementing Constructor based DI
		private UserRepository repository;
		
		public UserServiceImpl() {
			
		}
		
		@Autowired
		public UserServiceImpl(UserRepository repository) {
			super();
			this.repository = repository;
		}
		
	@Override
	public List<User> getAllUsers() {
		List<User> list = new ArrayList<User>();
		repository.findAll().forEach(e -> list.add(e));
		return list;
	}

	@Override
	public User getUserById(Long id) {
		User user = repository.findById(id).get();
		return user;
	}

	@Override
	public boolean saveUser(User user) {
		try {
			repository.save(user);
			return true;
		}catch(Exception ex) {
			return false;
		}
	}

	@Override
	public boolean deleteUserById(Long id) {
		try {
			repository.deleteById(id);
			return true;
		}catch(Exception ex) {
			return false;
		}
		
	}

}

[Rob Spoor]

Rob Spoor wrote:Also, autowiring only works if you let Spring create the instances. The way you're using Test, it's a simple POJO where nothing will get autowired.

I'm quoting myself because this is the reason nothing gets autowired.

[M Khalid]

Alejandro Barrero wrote:

@Service("userService")

Then you have to Autowire it and use it.

[Alejandro Barrero]

Thanks Rob; that shows my ignorance; could you please tell me how to correct the problem.

[Alejandro Barrero]

I appreciate the responses from all of you. Please tell me how and where do i use "@Service("userService")".

[M Khalid]

Alejandro Barrero wrote:I appreciate the responses from all of you. Please tell me how and where do i use "@Service("userService")".

package com.javaspringclub.service;
 
import java.util.ArrayList;
import java.util.List;[]
import javax.transaction.Transactional;
 
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
 
import com.javaspringclub.entity.User;
import com.javaspringclub.repository.UserRepository;
 
@Service("userService")
@Transactional
public class UserServiceImpl implements UserService {

[Alejandro Barrero]

Thanks Khalid, but I still have problems; I used '@Service("userService")' in class UserServiceImpl, but in class Test with 'private static UserService userService;' I am still getting userService null.

[M Khalid]

Alejandro Barrero wrote:Thanks Khalid, but I still have problems; I used '@Service("userService")' in class UserServiceImpl, but in class Test with 'private static UserService userService;' I am still getting userService null.

Directly invoke the method with userService object instead of creating new Test object.

[Alejandro Barrero]

I just did with

package com.javaspringclub.test;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;

import com.javaspringclub.entity.User;
import com.javaspringclub.service.UserService;

public class Test {
	@Autowired
	private static UserService userService;

	public static void main(String[] args) {
		List<User> userList = userService.getAllUsers();
		userList.forEach(user->System.out.println(user));
	}

}

Still doesn't work. I also tried with

	public static void main(String[] args) {
		UserService userService = new UserServiceImpl();
		List<User> userList = userService.getAllUsers();
		userList.forEach(user->System.out.println(user));
	}

but repository is null in getAllUsers() of UserServiceImpl

@Service("userService")
@Transactional
public class UserServiceImpl implements UserService {
		private UserRepository repository;
		@Autowired
		public UserServiceImpl(UserRepository repository) {
			super();
			this.repository = repository;
		}
...
	@Override
	public List<User> getAllUsers() {
		List<User> list = new ArrayList<User>();
		repository.findAll().forEach(e -> list.add(e));
		return list;
	}
...
}

[M Khalid]

Alejandro Barrero wrote:I just did with

package com.javaspringclub.test;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;

import com.javaspringclub.entity.User;
import com.javaspringclub.service.UserService;

public class Test {
	@Autowired
	private static UserService userService;

	public static void main(String[] args) {
		List<User> userList = userService.getAllUsers();
		userList.forEach(user->System.out.println(user));
	}

}

Still doesn't work. I also tried with

	public static void main(String[] args) {
		UserService userService = new UserServiceImpl();
		List<User> userList = userService.getAllUsers();
		userList.forEach(user->System.out.println(user));
	}

but repository is null in getAllUsers() of UserServiceImpl

@Service("userService")
@Transactional
public class UserServiceImpl implements UserService {
		private UserRepository repository;
		@Autowired
		public UserServiceImpl(UserRepository repository) {
			super();
			this.repository = repository;
		}
...
	@Override
	public List<User> getAllUsers() {
		List<User> list = new ArrayList<User>();
		repository.findAll().forEach(e -> list.add(e));
		return list;
	}
...
}

Because there is no data source.
You should refer to a tutorial first and then try implementing. I would suggest to go JournalDev or Bealdege tutorial sites

[Rob Spoor]

This problem is more or less repeated/continued at https://coderanch.com/t/698537/frameworks/Autowired-working-Spring-Framework#3278140.