spring boot dependency injection

Question

Im new to Spring, last couple of days I've been learning about it. Now Im trying to do something with it. It seems to me that with spring boot everything has changed. There is no applicationContext file, I should use @Bean. Ok. In in tutorials the code is working, for me it fails. What did I miss?

@SpringBootApplication
public class Application {

  public static void main(String[] args) {
    SpringApplication.run(Application.class, args);
  }
}

the controller:

@RestController
public class GreetingController {

private final Test test;

@Autowired
public GreetingController(Test test){
    this.test = test;
}

@RequestMapping("/greeting")
  public String greeting(@RequestParam(value = "name", defaultValue = "World") String name) {
    return "greeting" + test.getTest();
  }
}


class Test {

  public String getTest() {
    return "tetst";
  }
}

error:

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [hello.Test] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {}
at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:1301)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1047)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:942)
at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:813)
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:741)
... 18 more

I assume that bean has to be defined... But in tutorials there is no defenicion of bean.. Or I didnt see it.

Answer 1

Test class is not recognized as a Spring component. Therefore, you cannot inject it in your GreetingController. In order to inject Test object in that controller, annotate Test class with like @Component annotation (or with some other annotation that indicates that your class can be auto scanned).

Answer 2

Missed the full error. You need @Component on Test.