Spring Boot Core Container and Beans Questions and Answers

Question 1

Which of the following is the default scope for a Spring bean if no scope is explicitly specified?

Accepted Answer

singleton

Answer

In the Spring Framework, if no scope is specified for a bean, it defaults to the 'singleton' scope. This means the Spring IoC container creates exactly one instance of the bean, and that single instance is shared for all requests for that bean.

Question 2

A developer needs to create a new instance of a `ShoppingCart` bean every time a user starts a new HTTP session. Which bean scope should be used?

Accepted Answer

session

Answer

The 'session' scope creates a new bean instance for the lifetime of a single HTTP Session. This is ideal for stateful beans like a user's shopping cart, where the state is tied to a specific user's session.

Question 3

What is a primary difference between the `ApplicationContext` and `BeanFactory` IoC containers in Spring?

Accepted Answer

`ApplicationContext` is a sub-interface of `BeanFactory` and provides more advanced, enterprise-specific features like event publication and internationalization.

Answer

The `ApplicationContext` is a complete superset of the `BeanFactory`. It extends `BeanFactory` to provide more enterprise-level features such as event publication, message resource handling (for internationalization), and easier integration with Spring's AOP features. `ApplicationContext` typically loads all singleton beans eagerly at startup, whereas `BeanFactory` loads them lazily on demand.

Question 4

In a Spring Boot application, which annotation is considered the most generic stereotype for marking a class as a Spring-managed component?

Accepted Answer

@Component

Answer

@Component is the generic stereotype annotation for any Spring-managed component. @Service, @Repository, and @Controller are specializations of @Component for more specific use cases in the service, persistence, and presentation layers, respectively.

Question 5

A developer wants to ensure their dependency injection code is portable and not tightly coupled to the Spring Framework. Which annotation should they prefer for dependency injection?

Accepted Answer

@Inject

Answer

The `@Inject` annotation is part of the Java Dependency Injection standard (JSR-330). Using `@Inject` over Spring's specific `@Autowired` annotation makes the code more portable across different dependency injection frameworks that support the standard, like Google Guice.

Spring Boot Practice Test

Spring Boot Practice Test

Spring Boot Core Container and Beans Questions and Answers