Event-driven architecture pattern in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to publish an event using Spring Boot's ApplicationEventPublisher.

Spring Boot

applicationEventPublisher.[1](new CustomEvent(this, "Hello"));

Drag options to blanks, or click blank then click option'

ApublishEvent

BsendEvent

CfireEvent

DraiseEvent

Attempts:

3 left

💡 Hint

Common Mistakes

Using methods like sendEvent or fireEvent which do not exist.

In Spring Boot, publishEvent is the method used to send events.

2fill in blank

medium

Complete the code to listen for events using @EventListener annotation.

Spring Boot

@EventListener
public void handleEvent([1] event) {
    System.out.println(event.getMessage());
}

Drag options to blanks, or click blank then click option'

AObject

BCustomEvent

CApplicationEvent

DEvent

Attempts:

3 left

💡 Hint

Common Mistakes

Using generic types like Object or ApplicationEvent which may not match the event.

The method parameter should be the specific event class you want to listen to, here CustomEvent.

3fill in blank

hard

Fix the error in the event class by completing the constructor correctly.

Spring Boot

public class CustomEvent extends ApplicationEvent {
    private final String message;

    public CustomEvent(Object source, String message) {
        super([1]);
        this.message = message;
    }

    public String getMessage() {
        return message;
    }
}

Drag options to blanks, or click blank then click option'

Asource

Bmessage

Cthis

Devent

Attempts:

3 left

💡 Hint

Common Mistakes

Passing message or this instead of source to the superclass constructor.

The superclass constructor requires the source object, so pass source.

4fill in blank

hard

Fill both blanks to create a listener method that listens asynchronously and logs the event message.

Spring Boot

@Async
@EventListener
public void onEvent([1] event) {
    logger.[2]("Received: " + event.getMessage());
}

Drag options to blanks, or click blank then click option'

ACustomEvent

Binfo

Cdebug

DString

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong event type or logging level like debug instead of info.

The listener method should accept CustomEvent and use logger.info to log the message.

5fill in blank

hard

Fill all three blanks to define a Spring Boot event publisher bean and publish an event inside it.

Spring Boot

import org.springframework.context.ApplicationEventPublisher;
import org.springframework.stereotype.Component;

@Component
public class EventPublisher {

    private final ApplicationEventPublisher [1];

    public EventPublisher(ApplicationEventPublisher [2]) {
        this.[3] = [2];
    }

    public void publish(String message) {
        [1].publishEvent(new CustomEvent(this, message));
    }
}

Drag options to blanks, or click blank then click option'

Apublisher

BeventPublisher

CapplicationEventPublisher

DeventPub

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for field and constructor parameter causing confusion.

The standard name used is applicationEventPublisher for clarity and consistency.