CODEWITHSUNDEEP
spring-bootautowired
Akzwitch
Akzwitch

Reputation: 113

Spring Boot Autowired failed - null

I have 3 classes which are found in different packages in a spring boot application as follows: Why does @Autowired work in certain classes only?Anything I am doing wrong?

@Configuration
public class Configurations{
   @Autowired
   Prop prop;  //works fine

   @Bean
   //other bean definitions

}

@Component
public class Prop{
   public void method(){};
}

public class User{
   @Autowired
   Prop prop;  //does not work, null

   public void doWork(){
      prop.method();
   }

}

I have also tried the @PostConstruct, but same result

public class User{
       @Autowired
       Prop prop;  //does not work, null

       @PostConstruct
       public void doWork(){
          prop.method();
       }

    }

Upvotes: 2

Views: 5549

Answers (1)

Dimitri Mestdagh
Dimitri Mestdagh

Reputation: 44745

The @Autowired annotation works only if Spring detects that the class itself should be a Spring bean.

In your first example you annotated Configurations with the @Configuration annotation. Your User class on the other hand does not have an annotation indicating that it should be a Spring bean.

There are various annotations (with different meanings) to make your class being picked up by the Spring container, some examples are @Service, @Component, @Controller, @Configuration, ... . However, this only works if your class is in a package that is being scanned by the Spring container. With Spring boot, the easiest way to guarantee that is by putting your User class in a (sub)package of your main class (the class annotated with @SpringBootApplication).

You can also manually create your bean by writing the following method in your Configurations:

@Bean
public User user() {
    return new User();
}

In this case you don't have to annotate your User class, nor do you have to make sure that it is in a package that is being scanned.

Upvotes: 5

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