Understanding Spring Boot @Autowired

Question

I don\'t understand how spring boot\'s annotation @Autowired correctly works. Here is a simple example:

@SpringBootApplication
public class App          


        

Answer 1

When you call the init method from the constructor of class App, Spring has not yet autowired the dependencies into the App object. If you want to call this method after Spring has finished creating and autowiring the App object, then add a method with a @PostConstruct annotation to do this, for example:

@SpringBootApplication
public class App {
    @Autowired
    public Starter starter;

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

    public App() {
        System.out.println("constructor of App");
    }

    @PostConstruct
    public void init() {
        System.out.println("Calling starter.init");
        starter.init();
    }
}