1. @PostConstruct is a Springboot annotation that is applied to a method.
2. The method annotated with this is only triggered once, and is triggered in the bean life-cycle after the dependency injections.
3. The life-cycle of a Spring Bean goes like this: Constructor of the class is called --> Dependencies are injected --> @PostConstruct method is called.

When do we use this?

1. Initialization Logic: When you need to perform some custom initialization after all dependencies have been injected.
2. Resource Setup: When you need to set up resources or connections that the bean will use during its lifetime.
3. Configuration Validation: To validate that the bean has been properly configured before it starts processing requests.
4. Logging: To log a message indicating that the bean has been successfully initialized and is ready to be used.

Types of Methods to Annotate with @PostConstruct

1. The method should be a void method.
2. The method should not accept any arguments.
3. The method should not throw a checked exception.
4. The method should be non-static.