To run specific logic right after your Spring Boot application starts, you can use one of the following standard interfaces provided by Spring:

1. Using CommandLineRunner

• This interface runs after the Spring context is fully loaded.
• You get access to String[] args.

Example:

@Component
public class StartupRunner implements CommandLineRunner {

    @Override
    public void run(String... args) throws Exception {
        System.out.println("Application started. Running post-startup logic.");
        // your custom logic here
    }
}

2. Using ApplicationRunner

• Similar to CommandLineRunner, but uses ApplicationArguments which gives more structured access to arguments.

Example:

@Component
public class AppStartupRunner implements ApplicationRunner {

    @Override
    public void run(ApplicationArguments args) throws Exception {
        System.out.println("Startup logic with ApplicationRunner");
        // your logic here
    }
}

3. Using @EventListener(ApplicationReadyEvent.class)

• This runs after the entire Spring Boot app has started, including the web server.
• Ideal for logic that depends on the app being fully ready to serve requests.

Example:

@Component
public class StartupEventListener {

    @EventListener(ApplicationReadyEvent.class)
    public void onApplicationReady() {
        System.out.println("Application is ready. Running post-startup event logic.");
        // your logic here
    }
}

When to Use Which?

Use Case	Recommended Interface
Need command-line arguments	CommandLineRunner or ApplicationRunner
Need to execute logic after Spring context initialization but before accepting HTTP requests	CommandLineRunner
Need to execute logic after everything (including embedded Tomcat or Jetty) is fully up	@EventListener(ApplicationReadyEvent.class)