Senior backend questions,
answered with sources
The Java, Spring and system design questions that keep coming up.
1. How does Spring Boot decide which auto-configuration to apply?
Open the question for the full answer and sources.
Pick a track
Each track starts with the question we see most in job descriptions on Kuchup, then goes deeper.
Questions
30 questions. Newest first. Read time assumes you read the deep dive too.
- 1. How does Spring Boot decide which auto-configuration to apply?Java and Spring · 2 sources Hard 1 min
- 2. What happens internally when you add spring-boot-starter-web?Java and Spring · 2 sources Medium 1 min
- 3. Why does Spring Boot prefer convention over configuration?Java and Spring · 0 sources Easy 1 min
- 10. What is the role of SpringFactoriesLoader?Java and Spring · 3 sources Hard 1 min
- 22. Difference between @EnableAutoConfiguration and @Import?Java and Spring · 2 sources Medium 1 min
- 23. What happens when you exclude an auto-configuration class?Java and Spring · 1 sources Medium 1 min
- 11. How did Spring Boot remove XML configuration almost completely?Java and Spring · 2 sources Medium 1 min
- 5. What is the exact startup flow of a Spring Boot application?Java and Spring · 1 sources Hard 1 min
- 6. Difference between @ComponentScan and @SpringBootApplication?Java and Spring · 1 sources Easy 1 min
- 8. What happens if two beans of the same type exist without @Qualifier?Java and Spring · 3 sources Medium 2 min
- 14. What is the complete lifecycle of a Spring Bean?Java and Spring · 2 sources Hard 1 min
- 18. Difference between a @Configuration class and a normal class?Java and Spring · 1 sources Hard 1 min
- 20. What is the real use of CommandLineRunner?Java and Spring · 1 sources Easy 1 min
- 4. How does Spring Boot load application.properties internally?Java and Spring · 1 sources Medium 1 min
- 9. How does Spring Boot load profile-specific configurations?Java and Spring · 2 sources Medium 1 min
- 15. How does Spring Boot handle externalized configuration?Java and Spring · 1 sources Medium 1 min
- 16. What happens if application.yml and application.properties both exist?Java and Spring · 1 sources Medium 1 min
- 27. How does Spring Boot decide server port priority?Java and Spring · 2 sources Medium 1 min
- 13. How does Spring Boot manage dependency versions automatically?Java and Spring · 1 sources Medium 1 min
- 7. How does Spring Boot detect embedded Tomcat automatically?Java and Spring · 2 sources Hard 1 min
- 12. Difference between @RestController and @Controller internally?Java and Spring · 3 sources Easy 1 min
- 28. What happens internally when you hit a REST endpoint?Java and Spring · 2 sources Hard 1 min
- 21. How does Spring Boot handle exception translation?Java and Spring · 1 sources Medium 1 min
- 19. How does Spring Boot auto-create a DataSource?Java and Spring · 2 sources Medium 1 min
- 17. How does Spring Boot integrate with Actuator internally?Java and Spring · 1 sources Hard 1 min
- 26. How does Spring Boot handle logging by default?Java and Spring · 1 sources Easy 1 min
- 25. Difference between a fat JAR and a normal JAR?Java and Spring · 1 sources Easy 1 min
- 24. Why is Spring Boot perfect for microservices?Java and Spring · 0 sources Easy 1 min
- 29. Why is Spring Boot preferred for cloud-native apps?Java and Spring · 3 sources Easy 1 min
- 30. What are the most common Spring Boot performance mistakes?Java and Spring · 0 sources Hard 1 min
Interviewers can tell a memorised answer from an understood one. We write for the second kind.
How we write these
Every answer is written by us, in our own words. Each claim points to the place you can check it: official docs first, then books. If we could not find a source, the claim is not on the page.
Docs before blogs
Spring, PostgreSQL, Stripe and JDK docs come first. Blog posts only back up an example.
Short quotes only
From books we quote a line or two and give the chapter. The rest is our explanation.
Numbered citations
Every superscript number jumps to the source list at the bottom of the page.
Dated
Every page shows when it was last updated.
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