Code Room
Vibe codingHardvc-g390
Subject Ai code comprehensionLevel Senior–Staff~20 minCommon in Concurrency interviewsIndustries Software development, Technology

Question

You ask an AI to explain this Java cache so you can extend it. The agent says: "It's a thread-safe lazy-loading cache — ConcurrentHashMap guarantees that even under concurrent access, compute() runs at most once per key." You're about to add an expensive remote call inside compute(). Is the explanation correct, and how would you verify before relying on the at-most-once claim?

java
private final Map<String, Value> cache = new ConcurrentHashMap<>();Value get(String key) {  if (!cache.containsKey(key)) {    cache.put(key, compute(key));  }  return cache.get(key);}
What a strong answer looks like

Treat the AI’s output as a draft to verify, not an answer to trust. Name the specific flaw and the input that triggers it, say how you’d catch it — tests, edge cases, reading critically — and how you’d re-prompt or decompose to get it right.

Describe your solution

Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.

Run or narrate your approach, then ask the coach.