Interview practice by role
Java Developer Interview Practice
Java interviews cover the language and the JVM in depth, then move to services and data. Expect collections, concurrency and memory questions before design discussions.
160 practice questions4 topics5 typical rounds
How the interview usually runs
Loops differ by company. Treat this as a common pattern, not a fixed format.
- 01Screening callYour Java version, frameworks and the systems you maintained.
- 02Core JavaCollections, equals and hashCode, immutability, generics and exception handling.
- 03JVM and concurrencyGarbage collection, memory model, threads, locks and executors.
- 04Service and data designREST design, transactions, indexing and handling failures between services.
- 05Behavioural roundLegacy code, production issues and mentoring teammates.
What interviewers probe
- How HashMap works and what breaks it
- Thread safety and the cost of different locking strategies
- Garbage collection behaviour and tuning at a high level
- Transactions, isolation and what happens under concurrent writes
- Designing services that tolerate partial failure
Common mistakes
- Memorising collection facts without explaining the trade-offs
- Mixing up synchronisation tools without a use case
- Ignoring transactions when discussing data consistency
Practice questions for Java Developer interviews
A starting set from each topic. Every question has a short answer, the full reasoning and the follow-ups interviewers ask.
01Why is String immutable in Java?Mediumstring · immutability · string pool02What is the contract between equals and hashCode?Mediumequals · hashcode · collections03When would you use ArrayList versus LinkedList?Mediumarraylist · linkedlist · data structures04How does the Node.js event loop work?Mediumevent loop · libuv · async05Is Node.js single-threaded? What does that actually mean?Mediumnodejs · concurrency · libuv06How do you handle errors in a Node.js backend?Mediumerror handling · async · reliability07How do you choose between SQL and NoSQL databases?Mediumsql · nosql · data modelling08What is the difference between WHERE and HAVING?Mediumwhere · having · aggregation09What is the difference between INNER JOIN and LEFT JOIN?Mediuminner join · left join · nulls10How does load balancing work and how do you choose an algorithm?Mediumload balancing · l4 · l711How does database sharding work and what are the pitfalls?Mediumsharding · partitioning · hotspots12How does database replication work and what consistency issues does it create?Mediumreplication · replication lag · failover
Reading is step one
Now say it out loud.
Understanding an answer and delivering it under pressure are different skills. Rehearse this topic in a live Java Developer mock interview and get scored feedback on depth, clarity and confidence.