#Autowired annotation returns null [duplicate] - spring

Question

This question already has answers here:
Why is my Spring #Autowired field null?
(21 answers)
Closed 6 years ago.
When I develop in the Spring Framework, I wanted to get an access to DB using mybatis on the specific class, here is problem.
public class ScheduleManager {
private Scheduler scheduler;
#Autowired
private TriggerService triggerService;
public void doit() {
System.out.println(triggerService);
}
}
At here, value of triggerService is null. I think triggerService was not autowired.
But it is autowired at this class.
#Controller
public class TestController {
#Autowired
private TriggerService triggerService;
#RequestMapping("/scheduletest")
public String scheduleTest() {
System.out.println(triggerService);
ScheduleManager sm = new ScheduleManager();
sm.doit();
}
}
this code print some value not null.
dispatcher-servlet.xml
<?xml version="1.0" encoding="UTF-8" ?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<context:annotation-config/>
<context:component-scan base-package="com.scheduler"/>
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/views/"/>
<property name="suffix" value=".jsp"/>
<property name="contentType" value="text/html;charset=UTF-8"/>
<property name="order" value="0"/>
</bean>
</beans>
TriggerService interface
#Service
public interface TriggerService {
public List<Trigger> getAll();
}
Why does this problem appear?

Answer 1

You create the ScheduleManager instance by yourself:
ScheduleManager sm = new ScheduleManager();
So Spring doesn't know about this object and doesn't do any autowiring.
To resolve this, add the #Component annotation to ScheduleManager and let it also inject in the controller:
#Autowired
private ScheduleManager scheduleManager;

Answer 2

Your TriggerService is only an Interface, how could spring find the acutual implementation.
remove #Service from TriggerService and add it to one of the implementation of TriggerService will fix your problem