How does the @Qualifier annotation assist in Dependency Injection in Spring?

  • It defines a custom scope for a bean.
  • It marks a bean as a prototype, ensuring a new instance is created on each request.
  • It resolves circular dependencies in the Spring context.
  • It specifies the primary bean to be injected when multiple candidates exist.
The @Qualifier annotation in Spring is used to specify the exact bean to be injected when there are multiple candidates of the same type. This helps resolve ambiguity in cases where there are multiple beans of the same type that could be injected. By using @Qualifier with the bean's name, you can explicitly indicate which bean should be injected, ensuring that the correct one is selected. It's particularly useful when you have multiple beans of the same type and need to specify which one should be used for injection.

You are working on a Spring Boot project using Spring Data JPA, and you are tasked with implementing a feature that requires a custom query and also modifies the state of the underlying database. How would you implement this while ensuring that the changes are committed to the database?

  • Using a read-only transaction.
  • Using a read-write transaction with the @Transactional annotation on the method that modifies the data.
  • Using an in-memory database for testing purposes to avoid committing changes to the actual database during development.
  • Using two separate transactions for reading and writing, ensuring that the write transaction commits the changes.
In this scenario, you should use two separate transactions for reading and writing. The read transaction fetches the data, and the write transaction modifies the data and commits the changes to the database. This approach ensures that changes are committed while maintaining the integrity of the database. Using read-only transactions or in-memory databases for testing would not fulfill the requirement.

What is the significance of the spring-boot-starter-parent in a Spring Boot project's POM file?

  • It defines the parent project for the Spring Boot project.
  • It specifies the package version for Spring Boot.
  • It is used to configure the database connection.
  • It sets up the project's root directory.
The spring-boot-starter-parent in a Spring Boot project's POM file defines the parent project for the Spring Boot project. It provides default configurations and dependencies that are common to most Spring Boot projects, simplifying project setup and maintenance. This allows you to inherit common configurations, ensuring consistency across your Spring Boot projects. The other options do not accurately describe its significance.

The _____ in Spring Security can be used to execute some logic when a user logs in successfully.

  • AuthenticationFailureHandler
  • AuthenticationSuccessHandler
  • SecurityConfigurerAdapter
  • UserDetails
In Spring Security, the AuthenticationSuccessHandler interface can be used to execute custom logic when a user logs in successfully. This is useful for tasks like logging successful login attempts or redirecting users to specific pages after login. The AuthenticationSuccessHandler interface provides flexibility for handling successful authentication events.

The _____ annotation in Spring Data JPA can be used to eagerly fetch the associated entities from the database.

  • @EagerFetch
  • @Fetch
  • @FetchType.EAGER
  • @Fetch.EAGER
The @FetchType.EAGER annotation in Spring Data JPA can be used to eagerly fetch the associated entities from the database. When an entity is loaded, all its associations marked with FetchType.EAGER are fetched immediately along with the main entity, reducing the number of database queries. However, you should use this option judiciously as it can lead to performance issues if overused.

Which annotation is predominantly used in Spring Boot to write a JUnit test for a class?

  • @Autowired
  • @RunWith
  • @SpringBootTest
  • @Test
In Spring Boot, the @Test annotation is predominantly used to indicate that a method is a JUnit test method. It marks the method as a test to be run by the JUnit framework.

In JUnit, _____ tests allow you to run the same test multiple times with different arguments.

  • Iterative
  • Loop
  • MultiTest
  • Parameterized
In JUnit, Parameterized tests allow you to run the same test method multiple times with different sets of input arguments. This is useful for testing the same logic with various input values and ensuring that it behaves correctly for all cases.

How would you use Mockito to simulate the throwing of an exception by a method?

  • Use doThrow(Exception.class).when(mockedObject).methodCall()
  • Use expect(exception).when(mockedObject).methodCall()
  • Use mockedObject.throwException(Exception.class)
  • Use when(methodCall).thenThrow(Exception.class)
In Mockito, you can simulate the throwing of an exception by a method using doThrow(Exception.class).when(mockedObject).methodCall(). This sets up the behavior that when methodCall is invoked on mockedObject, it will throw the specified exception.

How can you specify a default value for a request parameter in a Spring Boot controller method?

  • Creating a custom annotation.
  • Default values for request parameters are not supported in Spring Boot.
  • Setting the default value in the application.properties file.
  • Using the @RequestParam annotation with the defaultValue attribute.
You can specify a default value for a request parameter in a Spring Boot controller method using the @RequestParam annotation with the defaultValue attribute. This attribute allows you to provide a default value that will be used if the parameter is not present in the request. Setting the default value in the application.properties file is not the correct approach, and creating a custom annotation is not a standard way to specify default values for request parameters.

In Spring Security, which class is primarily responsible for holding the authenticated user’s details?

  • UserDetails
  • UserPrincipal
  • AuthenticationDetails
  • SecurityContext
In Spring Security, the class primarily responsible for holding the authenticated user's details is UserDetails. It represents user information, including username, password, authorities, and account status. SecurityContext is used to hold the security context, and the other options do not typically hold user details.