Quiz: Getting Started with Spring Boot

Test your knowledge on creating and structuring a Spring Boot project.

30 questions - Click on each question to reveal the answer.

Questions 1-10: Spring Initializr and Structure

Question 1: What is Spring Initializr?

Answer: Spring Initializr is a web tool (start.spring.io) that generates the basic structure of a Spring Boot project:

Choice of project type (Maven/Gradle)
Java and Spring Boot version
Initial dependencies
Project metadata (groupId, artifactId)

Question 2: What is the standard structure of a Spring Boot project?

Answer:

src/
├── main/
│   ├── java/
│   │   └── com/example/demo/
│   │       └── DemoApplication.java
│   └── resources/
│       ├── application.properties
│       ├── static/
│       └── templates/
└── test/
    └── java/
pom.xml

Question 3: What is the purpose of the pom.xml file?

Answer: The pom.xml (Project Object Model) file defines:

Project metadata (groupId, artifactId, version)
Dependencies
Maven plugins
Build configuration
Spring Boot parent (spring-boot-starter-parent)

Question 4: What is spring-boot-starter-parent?

Answer: A Maven parent that provides:

Dependency version management
Default plugin configuration
UTF-8 encoding
Configured Java version
Build profiles

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>3.2.0</version>
</parent>

Question 5: What is a Spring Boot starter?

Answer: A starter is a set of pre-configured dependencies for a specific use:

Starter	Usage
`spring-boot-starter-web`	REST API
`spring-boot-starter-data-jpa`	Database
`spring-boot-starter-security`	Security
`spring-boot-starter-test`	Tests

Question 6: Where to place the application.properties file?

Answer: In src/main/resources/application.properties or application.yml.

This file contains the application configuration (port, database, etc.).

Question 7: What is the difference between application.properties and application.yml?

Answer:

# application.properties
server.port=8080
spring.datasource.url=jdbc:postgresql://localhost/db

# application.yml
server:
  port: 8080
spring:
  datasource:
    url: jdbc:postgresql://localhost/db

YAML is more readable for hierarchical configurations.

Question 8: What is the purpose of the static/ folder?

Answer: The src/main/resources/static/ folder contains static files served directly:

CSS
JavaScript
Images
Static HTML files

Accessible via http://localhost:8080/file.css

Question 9: What is the purpose of the templates/ folder?

Answer: The src/main/resources/templates/ folder contains server-side templates:

Thymeleaf (.html)
FreeMarker (.ftl)
Mustache (.mustache)

Used for web applications with server-side rendering.

Question 10: How to run a Spring Boot application?

Answer:

# With Maven
mvn spring-boot:run

# Or by compiling the JAR
mvn clean package
java -jar target/app.jar

# From the IDE
# Run the main class

Questions 11-20: Main Class and Annotations

Question 11: What does the main class contain?

Answer:

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

This is the entry point that starts the Spring context.

Question 12: What does @SpringBootApplication do?

Answer: @SpringBootApplication combines three annotations:

@Configuration: configuration class
@EnableAutoConfiguration: Spring Boot auto-configuration
@ComponentScan: component scanning

Question 13: What is auto-configuration?

Answer: Spring Boot automatically configures beans based on:

Present dependencies
Defined properties
Existing beans

Example: adding spring-boot-starter-data-jpa automatically configures a DataSource.

Question 14: What is @RestController?

Answer: Annotation combining:

@Controller: web component
@ResponseBody: returns JSON/XML

@RestController
public class UserController {
    
    @GetMapping("/users")
    public List<User> getAll() {
        return userService.findAll();
    }
}

Question 15: What are the HTTP mapping annotations?

Answer:

Annotation	HTTP Method
`@GetMapping`	GET
`@PostMapping`	POST
`@PutMapping`	PUT
`@DeleteMapping`	DELETE
`@PatchMapping`	PATCH
`@RequestMapping`	All (configurable)

Question 16: How to retrieve a URL parameter?

Answer:

// Path variable: /users/123
@GetMapping("/users/{id}")
public User getUser(@PathVariable Long id) {
    return userService.findById(id);
}

// Query param: /users?name=John
@GetMapping("/users")
public List<User> search(@RequestParam String name) {
    return userService.findByName(name);
}

Question 17: How to retrieve the body of a request?

Answer:

@PostMapping("/users")
public User create(@RequestBody UserRequest request) {
    return userService.create(request);
}

@RequestBody deserializes the JSON into a Java object.

Question 18: What are @Component, @Service, @Repository used for?

Answer: These are Spring stereotypes that mark classes as beans:

Annotation	Usage
`@Component`	Generic bean
`@Service`	Business logic
`@Repository`	Data access
`@Controller`	Web layer

All are variants of @Component.

Question 19: What are @Configuration and @Bean?

Answer:

@Configuration
public class AppConfig {
    
    @Bean
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

@Configuration: configuration class
@Bean: method that produces a bean

Question 20: How to inject a dependency?

Answer:

@Service
public class UserService {
    
    private final UserRepository userRepository;
    
    // Constructor injection (recommended)
    public UserService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }
}

Questions 21-30: Configuration and Repositories

Question 21: How to set the server port?

Answer:

# application.properties
server.port=9090

# application.yml
server:
  port: 9090

Default: 8080

Question 22: How to use profiles?

Answer:

# application.yml (common)
spring:
  profiles:
    active: dev

# application-dev.yml
server:
  port: 8080

# application-prod.yml
server:
  port: 80

Activation: --spring.profiles.active=prod

Question 23: How to read a configuration property?

Answer:

@Value("${app.name}")
private String appName;

@Value("${app.timeout:5000}")  // Default value
private int timeout;

Question 24: What is JpaRepository?

Answer: Spring Data JPA interface that provides CRUD methods:

public interface UserRepository extends JpaRepository<User, Long> {
    // Inherited methods: save, findById, findAll, delete, count...
}

Question 25: How to create a JPA entity?

Answer:

@Entity
@Table(name = "users")
public class User {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    @Column(nullable = false)
    private String name;
    
    private String email;
    
    // Getters, setters
}

Question 26: How to configure in-memory H2?

Answer:

spring:
  datasource:
    url: jdbc:h2:mem:testdb
    driver-class-name: org.h2.Driver
  h2:
    console:
      enabled: true  # Console: /h2-console

Perfect for development and testing.

Question 27: How does Spring Data generate queries?

Answer: By method name:

List<User> findByName(String name);
// SELECT * FROM users WHERE name = ?

List<User> findByEmailContaining(String email);
// SELECT * FROM users WHERE email LIKE '%?%'

List<User> findByAgeGreaterThanOrderByNameAsc(int age);
// SELECT * FROM users WHERE age > ? ORDER BY name ASC

Question 28: How to start the application with data?

Answer:

@Component
public class DataInitializer implements CommandLineRunner {
    
    private final UserRepository repository;
    
    @Override
    public void run(String... args) {
        repository.save(new User("Admin", "admin@example.com"));
    }
}

Or with src/main/resources/data.sql.

Question 29: How to see executed SQL queries?

Answer:

spring:
  jpa:
    show-sql: true
    properties:
      hibernate:
        format_sql: true

logging:
  level:
    org.hibernate.SQL: DEBUG
    org.hibernate.orm.jdbc.bind: TRACE

Question 30: How to create an executable JAR?

Answer:

mvn clean package

# Result: target/app-0.0.1-SNAPSHOT.jar

java -jar target/app-0.0.1-SNAPSHOT.jar

The JAR contains the application and an embedded Tomcat server.

Score

Score	Level
27-30	Excellent - Fundamentals mastered
21-26	Good - Some revisions needed
15-20	Average - Review the chapters
Less than 15	Needs review

Back to Module 2

Questions 1-10: Spring Initializr and Structure​

Questions 11-20: Main Class and Annotations​

Questions 21-30: Configuration and Repositories​

Score​

Questions 1-10: Spring Initializr and Structure

Questions 11-20: Main Class and Annotations

Questions 21-30: Configuration and Repositories

Score