Spring Boot Core Container and Beans 2

Question 1

Which annotation marks a method as a bean producer inside a @Configuration class?

Accepted Answer

@Bean

Answer

@Bean annotates methods in @Configuration classes so Spring registers the return value as a managed bean.

Question 2

What is the default bean scope in a Spring ApplicationContext?

Accepted Answer

singleton

Answer

Spring beans default to singleton scope, meaning one shared instance per ApplicationContext.

Question 3

Which interface can a bean implement to run code immediately after the ApplicationContext is fully started?

Accepted Answer

ApplicationRunner

Answer

ApplicationRunner's run() method is called after the context is refreshed and the application is ready.

Question 4

What happens when two beans of the same type exist and an @Autowired field has no @Qualifier?

Accepted Answer

Spring throws NoUniqueBeanDefinitionException

Answer

Without a qualifier Spring cannot choose between two matching beans and throws NoUniqueBeanDefinitionException.

Question 5

Which annotation would you add to a bean so Spring always creates a fresh instance for every injection point?

Accepted Answer

@Scope("prototype")

Answer

@Scope("prototype") tells Spring to create a new bean instance each time it is requested.

Spring Boot Practice Test