Given the controller and a Thymeleaf template `details.html` containing ` Value: `, what is the HTTP response body when accessing `/my-details`?

A) Value: Sample Data . Returning a `ModelAndView` object allows specifying both the view name ('details') and model attributes ('data'). Spring Boot will resolve and render `details.html` using the provided model data, resulting in the HTML snippet ` Value: Sample Data `.

Spring Boot MCQ Questions – Page 48 of 49

Q: What is the main benefit of using Dependency Injection (DI) in Spring Boot applications?

B) It reduces boilerplate code by externalizing dependency creation and management.. Dependency Injection centralizes the creation and management of dependencies within the Spring container, reducing boilerplate code in components and promoting loose coupling and testability.

Q: In a typical layered Spring Boot application, where do classes annotated with `@Service` commonly reside?

C) The Business Layer, orchestrating operations and applying business rules.. The `@Service` annotation is intended for the business layer, encapsulating the core business logic of the application. It acts as an intermediary between the controller and data access layers.

Q: What is the output of this code?

A) General Content. The `getGeneralContent` method requires that the user does *not* have the 'SUPER_ADMIN' role. The authenticated user has 'ROLE_USER', which is not 'ROLE_SUPER_ADMIN', so the condition is met and access is granted.

Q: What is the HTTP status returned by the MockMvc test?

A) 200 OK. The `get("/api/hello")` request maps to the `@GetMapping("/api/hello")` method in the `TestController`, which returns successfully. The `status().isOk()` assertion expects an HTTP 200 OK status.

Q: What is the most likely error when calling this POST endpoint with a JSON request body `{"name": "Laptop", "price": 1200.0}`?

A) HTTP 400 Bad Request due to missing `@RequestBody` for deserialization.. Without the `@RequestBody` annotation, Spring will attempt to bind the `Product` object from URI parameters or form data, not the JSON payload in the request body, leading to an HTTP 400 Bad Request error.

Q: What is the primary purpose of the `@RequestBody` annotation in a Spring Boot controller method?

B) To bind the contents of the HTTP request body to a Java object.. The `@RequestBody` annotation is used to indicate that a method parameter should be bound to the body of the HTTP request, typically converting JSON or XML into a Java object.

Q: A user named "devuser" with role "DEV" successfully logs in and then accesses the `/profile` endpoint. What does this code print?

A) Welcome, devuser! Your roles: [ROLE_DEV]. The `@AuthenticationPrincipal` annotation directly injects the authenticated `UserDetails` object into the method. For a logged-in 'devuser' with role 'DEV', it will correctly retrieve and display their information.

Q: What is the primary issue with this `deleteResource` endpoint implementation?

A) The resource will not be deleted from the persistent storage, despite a 204 No Content response.. The actual call to the `resourceService.delete(id)` method is commented out or missing. While the endpoint will return a 204 No Content status, the underlying deletion logic will not be executed, meaning the resource will remain in the database.

Q: What error occurs when accessing `/items/item123` with the following controller?

A) org.springframework.web.bind.MissingPathVariableException. Without the `@PathVariable` annotation, Spring MVC does not recognize that the method parameter `itemId` should be populated from the URI path variable. Consequently, it cannot find a value for the parameter, leading to a MissingPathVariableException.

Q941 medium

What is the main benefit of using Dependency Injection (DI) in Spring Boot applications?

Q942 medium

In a typical layered Spring Boot application, where do classes annotated with `@Service` commonly reside?

Q943 medium code output

What is the output of this code?

java

import org.springframework.security.access.prepost.PreAuthorize;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.context.SecurityContextHolder;
import java.util.Collections;

public class SecureService {
    @PreAuthorize("!hasRole('SUPER_ADMIN')")
    public String getGeneralContent() { return "General Content"; }
}

public class TestRunner {
    public static void main(String[] args) {
        SecurityContextHolder.getContext().setAuthentication(
            new UsernamePasswordAuthenticationToken("normalUser", "pass", Collections.singletonList(new SimpleGrantedAuthority("ROLE_USER")))
        );
        SecureService service = new SecureService();
        try { System.out.println(service.getGeneralContent()); }
        catch (Exception e) { System.out.println(e.getClass().getSimpleName()); }
    }
}

Q944 medium code output

What is the HTTP status returned by the MockMvc test?

java

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.test.web.servlet.MockMvc;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

@WebMvcTest(controllers = TestController.class)
class TestControllerTest {
    @Autowired
    private MockMvc mockMvc;

    @Test
    void testGetEndpoint() throws Exception {
        mockMvc.perform(get("/api/hello"))
               .andExpect(status().isOk());
    }
}

// Assuming TestController has:
// @RestController
// class TestController {
//    @GetMapping("/api/hello")
//    public String hello() { return "Hello MockMvc!"; }
// }

Q945 medium code output

Given the controller and a Thymeleaf template `details.html` containing `<p>Value: <span th:text='${data}'></span></p>`, what is the HTTP response body when accessing `/my-details`?

java

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.servlet.ModelAndView;

@Controller
public class MyDetailsController {

    @GetMapping("/my-details")
    public ModelAndView showDetails() {
        ModelAndView mav = new ModelAndView("details");
        mav.addObject("data", "Sample Data");
        return mav;
    }
}

Q946 medium code error

What is the most likely error when calling this POST endpoint with a JSON request body `{"name": "Laptop", "price": 1200.0}`?

java

import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/products")
public class ProductController {
    @PostMapping
    public String createProduct(Product product) {
        return "Product created: " + product.getName();
    }
}

class Product {
    private String name;
    private double price;
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public double getPrice() { return price; }
    public void setPrice(double price) { this.price = price; }
}

Q947 medium

What is the primary purpose of the `@RequestBody` annotation in a Spring Boot controller method?

Q948 medium code output

A user named "devuser" with role "DEV" successfully logs in and then accesses the `/profile` endpoint. What does this code print?

java

import org.springframework.security.core.annotation.AuthenticationPrincipal;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.provisioning.InMemoryUserDetailsManager;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

// Assume SecurityConfig and UserDetailsService are configured for a user:
// UserDetails user = User.withUsername("devuser").password("{noop}pass").roles("DEV").build();
// (InMemoryUserDetailsManager initialized with this user)

@RestController
public class ProfileController {
    @GetMapping("/profile")
    public String getProfile(@AuthenticationPrincipal UserDetails userDetails) {
        if (userDetails != null) {
            return "Welcome, " + userDetails.getUsername() + "! Your roles: " + userDetails.getAuthorities();
        }
        return "User not found or not authenticated.";
    }
}

Q949 medium code error

What is the primary issue with this `deleteResource` endpoint implementation?

java

import org.springframework.web.bind.annotation.*;
import org.springframework.http.ResponseEntity;

@RestController
@RequestMapping("/api/resources")
public class ResourceController {

    private ResourceService resourceService; // Assume injected

    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteResource(@PathVariable Long id) {
        // resourceService.delete(id); // Intended call is missing
        return ResponseEntity.noContent().build();
    }
}

Q950 medium code error

What error occurs when accessing `/items/item123` with the following controller?

java

import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/items")
public class ItemController {
    @GetMapping("/{itemId}")
    public String getItem(String itemId) {
        return "Item ID: " + itemId;
    }
}

Q951 medium code output

What does this code print to the console?

java

package com.example;

import jakarta.persistence.*;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
import java.util.Optional;

@Entity
public class Product {
    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private double price;

    public Product() {}
    public Product(Long id, String name, double price) { this.id = id; this.name = name; this.price = price; }
    public String getName() { return name; }
    public double getPrice() { return price; }
}

interface ProductRepository extends JpaRepository<Product, Long> {
    @Query("SELECT p FROM Product p WHERE p.id = :productId")
    Optional<Product> findProductByIdJPQL(@Param("productId") Long id);
}

// Assume ProductRepository is autowired as 'productRepository'
// And the database contains: Product(id=1, name='Laptop', price=1200.00)
Optional<Product> productOpt = productRepository.findProductByIdJPQL(1L);
System.out.println(productOpt.map(Product::getName).orElse("Not Found"));

Q952 medium code error

What error will the ApplicationContext throw during startup due to conflicting bean definitions?

java

import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Bean;

@Configuration
class ConflictingBeansConfig {
    @Bean("myString")
    public String stringBeanA() {
        return "First";
    }

    @Bean("myString") // Duplicate bean name
    public String stringBeanB() {
        return "Second";
    }
}

public class ConflictingBeanApp {
    public static void main(String[] args) {
        new AnnotationConfigApplicationContext(ConflictingBeansConfig.class);
    }
}

Q953 medium code output

What is the output of this code when a GET request is made to '/products?name=Laptop'?

java

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ProductController {
    @RequestMapping("/products")
    public String getProductByName(@RequestParam String name) {
        return "Product: " + name;
    }
}

Q954 medium code output

A user named "john.doe" with role "USER" successfully logs in and then accesses the `/user/details` endpoint. What does this code print?

java

import org.springframework.security.core.Authentication;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.provisioning.InMemoryUserDetailsManager;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

// Assume SecurityConfig and UserDetailsService are configured for a user:
// UserDetails user = User.withUsername("john.doe").password("{noop}pass").roles("USER").build();
// (InMemoryUserDetailsManager initialized with this user)

@RestController
public class UserController {
    @GetMapping("/user/details")
    public String getUserDetails() {
        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
        if (authentication != null && authentication.getPrincipal() instanceof UserDetails) {
            UserDetails userDetails = (UserDetails) authentication.getPrincipal();
            return "Username: " + userDetails.getUsername() + ", Roles: " + userDetails.getAuthorities();
        }
        return "Not authenticated or principal not UserDetails";
    }
}

Q955 medium code output

Given the Spring Boot controller, what is the HTTP status code and response body returned for a PUT request to `/api/items/101` with the JSON body `{"name": "Updated Item A", "description": "A new description for item A"}`?

java

import org.springframework.web.bind.annotation.*;
import org.springframework.http.ResponseEntity;
import java.util.HashMap;
import java.util.Map;

// Assume Item class has Long id, String name, String description, with getters/setters and a constructor.

@RestController
@RequestMapping("/api/items")
public class ItemController {
    private Map<Long, Item> items = new HashMap<>();

    public ItemController() {
        items.put(101L, new Item(101L, "Item A", "Original description A"));
        items.put(102L, new Item(102L, "Item B", "Original description B"));
    }

    @PutMapping("/{id}")
    public ResponseEntity<Item> updateItem(@PathVariable Long id, @RequestBody Item itemDetails) {
        if (!items.containsKey(id)) {
            return ResponseEntity.notFound().build();
        }
        Item existingItem = items.get(id);
        existingItem.setName(itemDetails.getName());
        existingItem.setDescription(itemDetails.getDescription());
        items.put(id, existingItem);
        return ResponseEntity.ok(existingItem);
    }
}

Q956 medium code error

What is the consequence if a view named 'dashboard' does not exist in a typical Spring Boot Thymeleaf setup for this controller?

java

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.ui.Model;

@Controller
public class DashboardController {

    @GetMapping("/dashboard")
    public String showDashboard(Model model) {
        model.addAttribute("user", "Admin");
        return "dashboard";
    }
}

Q957 medium code output

If a request is made to `/send`, what will be printed to the console when the `/receive` endpoint is subsequently processed due to the redirect?

java

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.ui.Model;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;

@Controller
public class MessageController {

    @GetMapping("/send")
    public String sendMessage(RedirectAttributes redirectAttributes) {
        redirectAttributes.addFlashAttribute("infoMessage", "Data saved successfully!");
        redirectAttributes.addAttribute("queryParam", "value"); // URL parameter
        return "redirect:/receive";
    }

    @GetMapping("/receive")
    public String receiveMessage(Model model) {
        System.out.println("Model attributes in /receive: " + model.asMap().keySet());
        return "displayMessage";
    }
}

Q958 medium code error

If the `jackson-dataformat-xml` dependency is *not* present in the classpath, what will happen when a client calls this POST endpoint?

java

import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/data")
public class DataController {
    @PostMapping(produces = "application/xml")
    public MyData createData(@RequestBody MyData data) {
        System.out.println("Received data: " + data.getContent());
        return data;
    }
}

class MyData {
    private String content;
    public String getContent() { return content; }
    public void setContent(String content) { this.content = content; }
}

Q959 medium code output

Given `application.properties` does NOT contain `config.value` and the following Java code, what does it print?

java

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
public class ConfigService {
    @Value("#{'${config.value:default-message}'.length()}")
    private int messageLength;

    public int getMessageLength() {
        return messageLength;
    }
}
// In a Spring Boot application, if this component is scanned:
// ConfigService service = applicationContext.getBean(ConfigService.class);
// System.out.println(service.getMessageLength());

Q960 medium

In a typical Spring Boot MVC/REST architecture, where should the actual logic for deleting a resource (e.g., calling a JPA repository method) primarily reside?

🌱 Spring Boot MCQ Questions – Page 48