IoC Container — Spring Technical Interview Questions & Answers

The container that creates and wires your beans.

IoC Container

  • The IoC container creates beans and injects their dependencies.
  • You describe what you need; the container decides how to provide it.
  • ApplicationContext is the common modern container interface.
  • This is the heart of Spring.
  • IoC = container controls object creation/wiring.

Technical Interview Tip: IoC container = bean factory + dependency wiring.

Code Examples for IoC Container

IoC Container — working example

// Topic: IoC Container
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
class TopicController {
  @GetMapping("/api/topic")
  String topic() {
    return "Spring Boot: IoC Container";
  }
}

IoC Container: GET /api/topic returns this title string.

How to Explain IoC Container to an Interviewer

What is IoC Container (spring)?

Used for a short IoC Container spring example a small REST app Not just the heading

Give one small example of IoC Container (spring).

the smallest IoC Container spring example you can type The container that creates and wires your beans

What mistake do beginners make with IoC Container (spring)?

only saying “IoC Container spring” with no example Show the fix

Where do you use IoC Container (spring)?

a small REST app a short IoC Container spring example