Hackforge Academy

Explanation

The @Async annotation in Spring Boot is used to execute a method asynchronously in a separate thread. This allows the caller to continue execution without waiting for the method to complete, improving application responsiveness.

Code:

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

Explanation

Annotate a method with @Async to run it in a background thread.

Code:

@Service
public class EmailService {

    @Async
    public void sendEmail() {
        System.out.println("
Sending email in background...");
    }
}

Explanation

Methods annotated with @Async can return a CompletableFuture for asynchronous result handling.

Code:

@Async
public CompletableFuture<String> 
processData() {
    return CompletableFuture.
completedFuture("Data Processed");
}

Explanation

Use @Async for long-running tasks such as sending emails, generating reports, processing files, or calling external APIs.

Code:

@Async
public void generateReport() {
    // Long-running report generation
}

Explanation

Without @Async, the caller waits for the method to finish. With @Async, the method runs in a separate thread and the caller continues immediately.

Code:

emailService.sendEmail();
System.out.println("Request completed 
without waiting for email.");