Spring / Spring7 basics Interview questions
Describe the Spring Bean lifecycle basics?
Every Spring bean moves through a predictable sequence of stages between creation and destruction, and the container exposes hook points at several of them for custom logic.
flowchart TD
A[Instantiate bean] --> B[Populate properties / inject dependencies]
B --> C[BeanNameAware, BeanFactoryAware callbacks]
C --> D[BeanPostProcessor - before init]
D --> E["@PostConstruct / afterPropertiesSet"]
E --> F[BeanPostProcessor - after init]
F --> G[Bean ready for use]
G --> H["@PreDestroy / destroy on context close"]
Constructor injection happens first, followed by any setter or field injection. Then Spring calls Aware interfaces if implemented, runs BeanPostProcessors before and after any @PostConstruct method, and finally the bean sits ready until the container shuts down and calls @PreDestroy - only for singleton beans, since prototype beans aren't tracked for destruction.
Which callback runs right before a singleton bean is considered fully ready for use?
Why doesn't Spring call @PreDestroy on prototype-scoped beans automatically?
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