Interview kitsBlog

Your dream job? Lets Git IT.
Interactive technical interview preparation platform designed for modern developers.

XGitHub

Platform

  • Categories

Resources

  • Blog
  • About the app
  • FAQ
  • Feedback

Legal

  • Privacy Policy
  • Terms of Service

© 2026 LetsGit.IT. All rights reserved.

LetsGit.IT/Categories/Java
Javahard

How can you have a memory leak in Java even with garbage collection?

Tags
#memory-leak#gc#references#caching
Back to categoryPractice quiz

Answer

GC frees only objects that are unreachable. If you keep references by mistake (e.g., a static list/map that grows, caches without eviction, listeners not removed), objects stay reachable and memory usage grows.

Advanced answer

Deep dive

Expanding on the short answer — what usually matters in practice:

  • Context (tags): memory-leak, gc, references, caching
  • JVM: memory (heap/stack), GC, and what drives latency.
  • Contracts: equals/hashCode/toString, mutability and consequences.
  • Performance: boxing, allocations, collections, inlining.
  • Explain the "why", not just the "what" (intuition + consequences).
  • Trade-offs: what you gain/lose (time, memory, complexity, risk).
  • Edge cases: empty inputs, large inputs, invalid inputs, concurrency.

Examples

A tiny example (an explanation template):

// Example: discuss trade-offs for "how-can-you-have-a-memory-leak-in-java-even-with"
function explain() {
  // Start from the core idea:
  // GC frees only objects that are unreachable. If you keep references by mistake (e.g., a sta
}

Common pitfalls

  • Too generic: no concrete trade-offs or examples.
  • Mixing average-case and worst-case (e.g., complexity).
  • Ignoring constraints: memory, concurrency, network/disk costs.

Interview follow-ups

  • When would you choose an alternative and why?

Related questions

Java
Generational garbage collection: why does the JVM split memory into young/old?
#java#gc#jvm
Java
What does `ThreadLocal` do and what is a common pitfall?
#threadlocal#concurrency#thread-pool
Java
WeakReference — what is it and when is it useful?
#weakreference
  • What production issues show up and how do you diagnose them?
  • How would you test edge cases?
  • #weakhashmap
    #gc
    Java
    How does Java GC work at a high level (and why is it generational)?
    #gc#jvm#memory
    Cloud
    What is a CDN and when should you use it?
    #cloud#cdn#performance