Autowired bean giving Null Pointer Exception - spring

Question

I am using Autowired annotation in a Service class to inject Dao dependency. The code I have written is:
public interface Service {
public List<String> getAllCountries() ;
}
public class ServiceImpl implements Service {
#Autowired
private TestDao testDao;
public TestDao getTestDao() {
return testDao;
}
public void setTestDao(TestDao testDao) {
this.testDao = testDao;
}
public List<String> getAllCountries() {
// TODO Auto-generated method stub
System.out.println("coming in here:" + testDao);
return testDao.getAllCountries();
}
}
public interface TestDao {
List<String> getAllCountries() ;
}
public class TestDaoImpl implements TestDao{
#Override
public List<String> getAllCountries() {
// TODO Auto-generated method stub
List<String> ls = new ArrayList<>();
ls.add("test1");
return ls;
}
}
And a controller
public class TestController {
public void doSth() {
Service service = new ServiceImpl();
try {
System.out.println("service obj:" + service);
List<String> list = service.getAllCountries();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Beans.xml:
<context:annotation-config/>
<bean id="controller" class="org.test.TestController"/>
<bean id="testDao" class="org.test.TestDaoImpl"/>
And a main class:
ApplicationContext context = new
ClassPathXmlApplicationContext("beans4.xml");
TestController obj= (TestController) context.getBean("controller");
obj.doSth();
But it is throwing NullPointerException in ServiceImpl class. These all classes are in the same package.
Can somebody help me understand what exactly is the issue?
Solution:
public class TestController {
#Autowired
Service service;
//remaining code as it is
}

Answer 1

Your Service class is not managed by Spring . Hence, the dependency is getting injected.
To make your service class managed,
You can use #Service stereo type annotation and do a component scan.
I mean,
package com;
#Service
public class ServiceImpl implement XXXX{
//Your changes
}
and in spring config file:
<context:component-scan base-package="com"/>

Answer 2

I did not see any bean declaration or annotation for the ServiceImpl.
//You canot do it like the following
#controller
class A{
ServiceImpl simp=new ServiceImpl();
}
class ServiceImpl{
#Autowired
Adao adoa;//throws NPE
}
//it should be like this
#Controller
class A{
#autowired
ServiceImpl simp;
}
#Service
class ServiceImpl{
#Autowired
Adao adoa;
}
#Repository
class Adao{
}

Answer 3

Your testDao dependency bean has not been injected and you need the Spring container that you are using annotations and also specify which packages need to be scanned for Autowiring by adding the following:
<context:annotation-config />
<context:component-scan base-package="org.test" />
You can look here on how you can auto wire spring beans.