Spring Boot MCQ Questions – Page 19 of 49

Q: Assuming a global configuration defines a `String` bean `appMessage` returning "Original Message", what is the output of this test code?

A) Test Overridden Message. An inner static class annotated with `@TestConfiguration` within a Spring Boot test is used to define beans specific to that test. These beans override any existing beans with the same name from the main application context, providing a test-specific configuration.

Q: What is the output of this code when a GET request is made to '/items'?

A) List of items.. @GetMapping is a convenience annotation that is a shortcut for @RequestMapping(method = RequestMethod.GET). A GET request to /items will thus invoke the getItems() method.

Q: What is the output when accessing `/params?id=123&name=TestUser&status=active`?

A) Received parameters: {id=123, name=TestUser, status=active}. Using `@RequestParam Map ` allows collecting all query parameters into a map, where keys are parameter names and values are their corresponding string values. The order of entries in the map is not guaranteed.

Q: Which of the following annotations is primarily used within a `@Configuration` class to explicitly declare a single bean definition, allowing for complex setup logic or when defining beans for third-party classes?

A) @Bean. @Bean is used on a method within a @Configuration class to produce an instance of a bean. The method's return type defines the bean type, and the method name often defines the bean ID.

Q: You have two distinct beans of the same type in your Spring `ApplicationContext`. Which annotation would you use with `@Autowired` to specify which particular bean should be injected by its name or qualifier?

C) `@Qualifier`. `@Qualifier` is used alongside `@Autowired` to resolve ambiguity when multiple beans of the same type are available, allowing you to specify the exact bean by its unique name or qualifier.

Q: What is typically printed to the console when this Spring Boot application starts up with `spring-boot-starter-security` on the classpath, without any custom security configuration?

A) "Using generated security password:" followed by a random UUID string.. By default, if `spring-boot-starter-security` is on the classpath without custom configuration, Spring Boot generates a random password for a 'user' user and prints it to the console for convenience.

Q: What error will prevent this code from compiling?

B) Compilation error: Attribute value must be constant.. Annotation attributes of type String[] must be compile-time constants. `MediaType.APPLICATION_JSON` is a `MediaType` object, not a `String` constant. You should use `MediaType.APPLICATION_JSON_VALUE` for string representation.

Q: Which of the following annotations acts as a general-purpose stereotype for any Spring-managed component, and is also the meta-annotation for more specific types like `@Service` and `@Repository`?

D) `@Component`. `@Component` is a generic stereotype annotation that indicates a class is a Spring component. `@Service`, `@Repository`, and `@Controller` are specialized forms of `@Component` that add semantic meaning.

Q: What is the approximate output after 5-6 seconds of the application running, given the following scheduled task? Assume the application starts at T=0.

B) Initial Delay Task executed. Counter: 0 Initial Delay Task executed. Counter: 1 Initial Delay Task executed. Counter: 2. The `initialDelay = 2000` means the first execution occurs 2 seconds after application startup (T=2s). After that, `fixedRate = 1000` makes it run every 1 second. So, executions will be at T=2s (Counter 0), T=3s (Counter 1), T=4s (Counter 2). After 5-6 seconds, it would have executed 3 times. We assume `@EnableScheduling` is present.

Q: In the following controller, what HTTP status code and body would be returned if a DELETE request is sent to `/api/accounts/123` and `accountService.archiveAccount(123L)` throws a `PermissionDeniedException` (a custom unchecked exception without `@ResponseStatus`)?

C) HTTP 500 Internal Server Error, with a generic error message.. If an unchecked exception without an `@ResponseStatus` annotation or explicit `@ExceptionHandler` handling is thrown, Spring Boot's default behavior is to return an HTTP 500 Internal Server Error.

Q361 medium code output

Assuming a global configuration defines a `String` bean `appMessage` returning "Original Message", what is the output of this test code?

java

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.context.TestConfiguration;
import org.springframework.context.annotation.Bean;

@SpringBootTest
class TestConfigurationOverrideTest {
    @Autowired
    String appMessage;

    @Test
    void testMessageOverride() {
        System.out.print(appMessage);
    }

    @TestConfiguration
    static class MyTestConfig {
        @Bean
        public String appMessage() {
            return "Test Overridden Message";
        }
    }
}

Q362 medium code output

What is the output of this code when a GET request is made to '/items'?

java

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ItemController {
    @GetMapping("/items")
    public String getItems() {
        return "List of items.";
    }

    @PostMapping("/items")
    public String createItem() {
        return "Item created.";
    }
}

Q363 medium code output

What is the output when accessing `/params?id=123&name=TestUser&status=active`?

java

import org.springframework.web.bind.annotation.*;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import java.util.Map;

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

    @GetMapping("/params")
    public String getAllParams(@RequestParam Map<String, String> allParams) {
        return "Received parameters: " + allParams;
    }
}

Q364 medium

Which of the following annotations is primarily used within a `@Configuration` class to explicitly declare a single bean definition, allowing for complex setup logic or when defining beans for third-party classes?

Q365 medium

You have two distinct beans of the same type in your Spring `ApplicationContext`. Which annotation would you use with `@Autowired` to specify which particular bean should be injected by its name or qualifier?

Q366 medium code output

What is typically printed to the console when this Spring Boot application starts up with `spring-boot-starter-security` on the classpath, without any custom security configuration?

java

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

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

@RestController
public class HomeController {
    @GetMapping("/")
    public String home() {
        return "Welcome!";
    }
}

Q367 medium code error

What error will prevent this code from compiling?

java

import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class MyController {

    @GetMapping(value = "/api/data", produces = {MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML})
    public String getData() {
        return "{ \"key\": \"value\" }";
    }
}

Q368 medium

Which of the following annotations acts as a general-purpose stereotype for any Spring-managed component, and is also the meta-annotation for more specific types like `@Service` and `@Repository`?

Q369 medium code output

What is the approximate output after 5-6 seconds of the application running, given the following scheduled task? Assume the application starts at T=0.

java

import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

@Component
public class InitialDelayScheduler {

    private int counter = 0;

    @Scheduled(initialDelay = 2000, fixedRate = 1000)
    public void runInitialDelayTask() {
        System.out.println("Initial Delay Task executed. Counter: " + counter++);
    }
}

Q370 medium code output

In the following controller, what HTTP status code and body would be returned if a DELETE request is sent to `/api/accounts/123` and `accountService.archiveAccount(123L)` throws a `PermissionDeniedException` (a custom unchecked exception without `@ResponseStatus`)?

java

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

// Assume PermissionDeniedException extends RuntimeException

@RestController
@RequestMapping("/api/accounts")
public class AccountController {

    private AccountService accountService;

    // Constructor injected accountService

    @DeleteMapping("/{id}")
    public ResponseEntity<Void> archiveAccount(@PathVariable Long id) {
        accountService.archiveAccount(id);
        return ResponseEntity.noContent().build();
    }
}

Q371 medium code error

What error will occur at runtime if a POST request with `Content-Type: text/plain` is sent with a JSON body `{"name": "Bob"}` to the `/api/create` endpoint?

java

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

@RestController
public class MyController {
    @PostMapping("/api/create")
    public String create(@RequestBody MyDto dto) {
        return "Created: " + dto.getName();
    }
}
// Assume MyDto exists with public String getName();

Q372 medium

To conditionally register a bean only if a specific configuration property exists and has a particular value, which annotation would you use?

Q373 medium code output

Given the following Feign client interface and a simulated call, what is the output of this code?

java

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

@FeignClient(name = "userService", url = "http://localhost:8080")
interface UserServiceClient {
    @GetMapping("/users/{id}")
    String getUserDetails(@PathVariable("id") Long id);
}

public class TestApplication {
    public static void main(String[] args) {
        UserServiceClient client = id -> "User ID: " + id + " | Name: John Doe"; // Mock implementation
        System.out.println(client.getUserDetails(123L));
    }
}

Q374 medium

Which of the following options correctly describes how to allow overriding bean definitions in a Spring Boot application if the same bean ID is defined multiple times?

Q375 medium code output

What is the expected outcome when saving a `Report` associated with an existing `User`, where `Report` uses `@MapsId` to share the primary key with `User`?

java

import jakarta.persistence.*;

@Entity
public class User {
    @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id;
    private String username;
    public User() {} public User(String username) { this.username = username; } public Long getId() { return id; }
}

@Entity
public class Report {
    @Id private Long userId;
    @MapsId("userId")
    @OneToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "user_id")
    private User user;
    private String reportContent;
    public Report() {} public Report(User user, String content) { this.user = user; this.reportContent = content; }
    public Long getUserId() { return userId; } public User getUser() { return user; }
}

// Assume userRepository and reportRepository are injected
// Assume transaction context is active
User newUser = new User("testuser");
userRepository.save(newUser);

Report report = new Report(newUser, "Monthly activity report");
reportRepository.save(report);

System.out.println("User ID: " + newUser.getId() + ", Report User ID: " + report.getUserId());

Q376 medium code output

What is the HTTP status and body returned by the `submitReport` method when a POST request is made to `/reports?type=bug` with the JSON body `{"details": "App crash"}` (Content-Type: application/json)?

java

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

class Report {
    private String details;
    public String getDetails() { return details; }
    public void setDetails(String details) { this.details = details; }
}

@RestController
@RequestMapping("/reports")
class ReportController {
    @PostMapping
    public ResponseEntity<String> submitReport(@RequestParam(required = false) String type, @RequestBody Report report) {
        String response = "Report details: " + report.getDetails();
        if (type != null && !type.isEmpty()) {
            response += " (Type: " + type + ")";
        }
        return new ResponseEntity<>(response, HttpStatus.ACCEPTED);
    }
}

Q377 medium code error

What will be the outcome when starting a Spring Boot application with this configuration?

java

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

// Assume 'com.example.NonSpringDependency' is a simple POJO, not a Spring bean.
package com.example;
public class NonSpringDependency {}

@Configuration
public class AppConfig {
    @Bean
    public String myService(NonSpringDependency dependency) {
        return "Service using " + dependency.getClass().getSimpleName();
    }

Q378 medium code output

What is the output of the following Spring Boot code?

java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.stereotype.Component;

interface PaymentGateway { String processPayment(); }

@Component("paypalGateway")
class PayPalGateway implements PaymentGateway { @Override public String processPayment() { return "Processing payment via PayPal"; } }

@Component("stripeGateway")
class StripeGateway implements PaymentGateway { @Override public String processPayment() { return "Processing payment via Stripe"; } }

@Component
class PaymentRunner implements CommandLineRunner {
    @Autowired
    @Qualifier("paypalGateway")
    private PaymentGateway selectedGateway;

    @Override
    public void run(String... args) { System.out.println(selectedGateway.processPayment()); }
}

@SpringBootApplication
class App {}

Q379 medium

A controller method needs to accept an optional query parameter named `page`. If the parameter is not present, it should default to `1`. How would you correctly define this parameter in the method signature?

Q380 medium code output

Given the Spring Boot controller above, what will be the HTTP response body when a GET request is made to `/data/products/500`?

java

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class DataController {
    @GetMapping("/data/{category}/{id}")
    public String getResource(@PathVariable String category, @PathVariable int id) {
        return "Category: " + category + ", ID: " + id;
    }
}

🌱 Spring Boot MCQ Questions – Page 19