Spring Core & Dependency Injection Flashcards

What annotation limits the @Autowired candidate beans to a specific name?

Answer: @Qualifier

@Qualifier is used alongside @Autowired to narrow down the injection candidate when multiple beans of the same type exist.

Which interface must be implemented to create a custom BeanPostProcessor in Spring?

Answer: BeanPostProcessor

Implementing the BeanPostProcessor interface allows custom logic to be applied before and after a bean's initialization callbacks.

How do you specify the initialization method for a Spring bean in a @Bean definition?

Answer: @Bean(initMethod="methodName")

The initMethod attribute of @Bean specifies the name of the method to call after the bean is initialized by the container.

What is the purpose of @Primary in Spring dependency injection?

Answer: Designates a bean as the default candidate when multiple beans of the same type exist

@Primary designates a bean as the preferred candidate for auto-wiring when multiple beans of the same type are present in the container.

What is a Spring bean's lifecycle callback that executes before the bean is destroyed?

Answer: @PreDestroy

@PreDestroy marks a method to be called just before the bean is removed from the container, allowing cleanup of resources.

In Spring, what is meant by 'circular dependency'?

Answer: Two or more beans that depend on each other either directly or indirectly

A circular dependency occurs when Bean A depends on Bean B and Bean B depends on Bean A, which can cause Spring to throw a BeanCurrentlyInCreationException with constructor injection.