🧠 Quiz – Week 5: Spring Boot

This quiz is designed to test your understanding of:

• Spring Boot fundamentals
• REST APIs
• Dependency Injection
• Backend architecture

👉 Try to answer without referring to notes.

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📘 Section 1: Conceptual Questions

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1. What problem does Spring Framework solve?

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2. What is Inversion of Control (IoC)?

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3. What is Dependency Injection?

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4. Difference between Spring and Spring Boot?

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5. What is a REST API?

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6. What does @SpringBootApplication do?

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7. What is the role of @RestController?

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8. Why do we use @RequestMapping?

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9. Difference between:

• @GetMapping
• @PostMapping

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10. What is the purpose of application.properties?

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💻 Section 2: Code Understanding

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11. What is wrong in the following code?

```java id=”2wblvr” @RestController public class UserController {

@GetMapping("/users")
public List<String> getUsers() {
    UserService service = new UserService();
    return service.getUsers();
} } ```

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12. What will happen if Spring cannot find a bean to inject?

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13. What is the output of this API?

```java id=”mb4npb” @GetMapping(“/test”) public String test() { return “Spring Boot Working!”; }

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### 14. Identify the mistake:

```java id="sv3h83"
@Service
public class UserService {
}

```java id=”2a0md8” @RestController public class UserController {

private UserService userService;

public UserController() {
    this.userService = new UserService();
} } ```

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🛠 Section 3: Practical Thinking

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15. Design an API to:

• Get all products
• Add a product

What endpoints will you create?

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16. Where should business logic be written?

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17. Why should controllers be kept thin?

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18. What happens if multiple responsibilities are placed in one class?

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🧪 Section 4: API Testing

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19. How will you test a POST API?

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20. What status code should be returned for:

• Successful GET
• Resource created
• Invalid request
• Resource not found

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21. What happens if you call:

GET /invalid-endpoint

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🔍 Section 5: Debugging & Scenario-Based

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22. Your API is returning 500 Internal Server Error. What will you check?

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23. Your API is not getting called. What could be the reasons?

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24. You added a service class but Spring is not injecting it. Why?

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25. You wrote a REST API but browser shows 404. What could be wrong?

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🏁 Self-Evaluation

After completing this quiz, you should be able to:

✔ Explain core Spring concepts ✔ Understand REST APIs ✔ Identify common mistakes ✔ Think like a backend developer

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