Why service layer matters in Spring Boot - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a service class in Spring Boot.

Spring Boot

@[1]
public class UserService {
    // service methods
}

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AComponent

BController

CRepository

DService

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Controller instead of @Service

Forgetting the @Service annotation

The @Service annotation marks the class as a service layer component in Spring Boot.

2fill in blank

medium

Complete the code to inject the repository into the service class.

Spring Boot

@Service
public class UserService {
    private final UserRepository userRepository;

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

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AUserService

BUserRepository

CUserController

DUserEntity

Attempts:

3 left

💡 Hint

Common Mistakes

Using the service class as parameter

Using the entity class instead of repository

The constructor parameter must be the repository type to inject it into the service.

3fill in blank

hard

Fix the error in the service method that calls the repository.

Spring Boot

public List<User> getAllUsers() {
    return userRepository.[1]();
}

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AgetUsers

BfindAllUsers

CfindAll

DlistAll

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-existent repository methods

Misspelling method names

The correct repository method to get all records is findAll().

4fill in blank

hard

Fill both blanks to create a service method that saves a user entity.

Spring Boot

public User [1](User user) {
    return userRepository.[2](user);
}

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AsaveUser

Bsave

CaddUser

Dinsert

Attempts:

3 left

💡 Hint

Common Mistakes

Using repository method names as service method names

Using incorrect repository methods

The service method name can be saveUser, and the repository method to save is save.

5fill in blank

hard

Fill all three blanks to create a service method that deletes a user by id.

Spring Boot

public void [1](Long [2]) {
    userRepository.[3]([2]);
}

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AdeleteUserById

Bid

CdeleteById

DremoveUser

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong parameter names

Using incorrect repository delete methods

The service method is named deleteUserById, the parameter is id, and the repository method to delete by id is deleteById.