IoC container mental model in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a Spring bean using annotation.

Spring Boot

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

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

AUser

BAutowired

CRepository

DController

Attempts:

3 left

💡 Hint

Common Mistakes

Using annotation names like @Autowired instead of class names.

Using unrelated class names like Repository or Controller.

The class name should represent the service, so UserService is correct here.

2fill in blank

medium

Complete the code to inject a bean using Spring's dependency injection.

Spring Boot

public class UserController {
    @[1]
    private UserService userService;
}

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

AComponent

BRepository

CAutowired

DService

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Component or @Service which are for bean declaration, not injection.

Using @Repository which is for data access layers.

The @Autowired annotation tells Spring to inject the bean automatically.

3fill in blank

hard

Fix the error in the bean declaration by completing the annotation.

Spring Boot

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

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

AAutowired

BRepository

CComponent

DService

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Autowired which is for injection, not declaration.

Using @Component which works but is less specific.

Using @Repository which is for data access.

The @Service annotation is the best practice to declare a service bean in Spring.

4fill in blank

hard

Fill both blanks to complete the code for constructor injection in Spring.

Spring Boot

public class PaymentController {
    private final PaymentService paymentService;

    public PaymentController([1] paymentService) {
        this.[2] = paymentService;
    }
}

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

APaymentService

BpaymentService

CPaymentController

Dthis

Attempts:

3 left

💡 Hint

Common Mistakes

Using the class name as the field name.

Using 'this' instead of the field name.

The constructor parameter type is PaymentService and the field assigned is paymentService.

5fill in blank

hard

Fill all three blanks to complete the code for a Spring configuration class defining a bean.

Spring Boot

@Configuration
public class AppConfig {

    @Bean
    public UserService [1]() {
        return new [2]();
    }

    @Bean
    public UserRepository [3]() {
        return new UserRepository();
    }
}

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

AuserService

BUserService

CuserRepository

DUserRepository

Attempts:

3 left

💡 Hint

Common Mistakes

Using class names as method names.

Mixing up method names and class names.

The method names for beans are usually camelCase like userService and userRepository. The classes are PascalCase like UserService.