Technical screening questions
Ask for one example per question and listen for specifics.
- How does the JVM garbage collector affect latency, and what have you tuned? A good answer: A strong answer names a collector (G1, ZGC), heap sizing and a real pause problem they fixed.
- Explain how Spring dependency injection and bean scopes work. A good answer: Should cover constructor injection, singleton vs prototype scope and why constructor injection is preferred.
- How do you prevent N+1 queries with JPA? A good answer: Look for fetch joins, entity graphs or batch fetching, and knowing how to spot it in logs.
- What is the difference between a checked and unchecked exception, and how do you handle errors in a REST API? A good answer: Expect a global exception handler and meaningful HTTP status codes.
- How would you make a service idempotent? A good answer: Idempotency keys, safe retries and handling duplicate messages.
Quick screening questions
Use these when you have only a few minutes.
- Which Java version did you ship to production last, and what did you move from?
- How have you handled transactions across microservices?
- Describe a performance problem you diagnosed in a Spring service.
What separates the levels
Match the level to the requirement before you submit.
- Junior: writes features within an existing service and needs guidance on design.
- Mid: owns a service end to end and handles production issues.
- Senior: sets service boundaries, reviews design and mentors others.
Red flags
Any of these is a reason to probe further.
- Cannot say which Java version the last project used.
- Lists Spring but has only used it through copy-pasted configuration.
- No experience with automated tests.
Tools you should hear mentioned
A Java developer with real experience usually names several of these without prompting.
- Spring Boot
- Maven or Gradle
- JUnit and Mockito
- Hibernate or JPA
- Kafka or RabbitMQ
- Docker
Run the call well
Ask for the last project first, then dig into the second or third question. Take notes on versions, team size and outcomes, and record them with the submission so the vendor’s later technical interview does not surprise you.
Frequently asked questions
How long should a Java developer screening call take?
Fifteen to twenty minutes is enough to cover the project, three technical questions and availability, rate and work authorization.
Do recruiters need to know the technology?
Working vocabulary is enough. Use the sourcing guide for the role and listen for specifics instead of judging technical depth yourself.