🧑‍⚖️ Interviewer Mode

Prepare Questions For Your Candidate

Pick a technology and experience level. Get warmups, scenarios, coding tasks, follow-ups, what to listen for, red flags, and a scoring rubric.

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Core Java · 3-5 years

Interview kit

👋Warmup Questions

  • ›How does HashMap work internally? Walk me through put().
  • ›fail-fast vs fail-safe iterators — give an example of each.
  • ›When would you choose ConcurrentHashMap over a synchronized map?

🎬Scenario Questions

  • ›A service slows down under load; profiling shows heavy GC. How do you investigate?
  • ›Two threads update a shared counter and you see lost updates. Walk me through the fix.

⌨️Coding Questions

  • ›Implement an LRU cache using LinkedHashMap.
  • ›Group a list of employees by department using Streams.

🔁Follow-up Questions

  • ›What changed in HashMap in Java 8 (treeification)?
  • ›Explain the volatile keyword and the happens-before relationship.

✅Expected Answer Keywords

  • ›treeify threshold (8)
  • ›load factor
  • ›happens-before
  • ›CAS
  • ›generational GC

🚩Red Flags

  • ⚠Thinks HashMap is thread-safe
  • ⚠Cannot explain volatile vs synchronized
  • ⚠No awareness of GC or memory tuning

📊 Evaluation Rubric

Knowledge★★★★★
Coding★★★★★
Problem Solving★★★★★
Communication★★★★★

Stars indicate the expected bar for this level — score the candidate against it, not in absolute terms.