Why enterprise patterns matter in Spring Boot - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a Spring Boot main application class.

Spring Boot

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.[1](Application.class, args);
    }
}

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Arun

Bstart

Claunch

Dexecute

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'start' or 'launch' instead of 'run' causes errors.

Forgetting to call a method to start the app.

The SpringApplication.run() method starts the Spring Boot application.

2fill in blank

medium

Complete the code to declare a Spring component for dependency injection.

Spring Boot

import org.springframework.stereotype.[1];

@[1]
public class Service {
    // service logic
}

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AComponent

BService

CRepository

DController

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Service or @Repository when a generic component is needed.

Forgetting to annotate the class for Spring to detect it.

The @Component annotation marks a class as a Spring-managed component for dependency injection.

3fill in blank

hard

Fix the error in the code to inject a repository into a service using constructor injection.

Spring Boot

import org.springframework.stereotype.Service;
import org.springframework.beans.factory.annotation.Autowired;

@Service
public class UserService {
    private final UserRepository userRepository;

    @Autowired
    public UserService([1] userRepository) {
        this.userRepository = userRepository;
    }
}

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AUserService

BUserRepository

CRepository

DUserRepo

Attempts:

3 left

💡 Hint

Common Mistakes

Using the service class type as parameter causes errors.

Using incorrect or undefined types for injection.

The constructor parameter must be the type of the repository to inject, here UserRepository.

4fill in blank

hard

Fill both blanks to create a REST controller method that handles GET requests and returns a list.

Spring Boot

import org.springframework.web.bind.annotation.[1];
import org.springframework.web.bind.annotation.RestController;
import java.util.List;

@RestController
public class ItemController {

    @[2]("/items")
    public List<String> getItems() {
        return List.of("apple", "banana", "cherry");
    }
}

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AGetMapping

BPostMapping

CRequestMapping

DDeleteMapping

Attempts:

3 left

💡 Hint

Common Mistakes

Using @PostMapping or @DeleteMapping for GET requests.

Importing a different annotation than the one used.

The method should be annotated with @GetMapping to handle GET requests. The import must match the annotation used.

5fill in blank

hard

Fill all three blanks to define a Spring Data JPA repository interface for an entity User with Long id.

Spring Boot

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.[1];

@[1]
public interface UserRepository extends JpaRepository<[2], [3]> {
}

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ARepository

BUser

CLong

DService

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Service instead of @Repository.

Mixing up entity and ID types in JpaRepository.

The interface should be annotated with @Repository. It extends JpaRepository with the entity User and ID type Long.