The stack is per‑thread memory holding call frames, local primitives and references; it’s allocated/deallocated on method entry/exit and is very fast. The heap is shared memory where all objects and arrays live; it’s managed by the garbage collector and objects usually outlive a single method call.
Advanced answer
Deep dive
Expanding on the short answer — what usually matters in practice:
Context (tags): memory, stack, heap, jvm, java
JVM: memory (heap/stack), GC, and what drives latency.
Contracts: equals/hashCode/toString, mutability and consequences.
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 "java-memory-model:-stack-vs-heap?"
function explain() {
// Start from the core idea:
// Stack stores local variables and method calls (fast access). Heap stores all objects (slow
}
Common pitfalls
Too generic: no concrete trade-offs or examples.
Mixing average-case and worst-case (e.g., complexity).