Javamedium

What is try-with-resources and why should you use it?

Answer

It automatically closes resources that implement `AutoCloseable` (files, streams, JDBC) even when exceptions happen. It prevents leaks and keeps cleanup logic reliable and simple.

try (var in = Files.newInputStream(path)) {
  return new String(in.readAllBytes(), StandardCharsets.UTF_8);
}

Advanced answer

Deep dive

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

Context (tags): try-with-resources, autocloseable, io
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

Here’s an additional example (building on the short answer):

try (var in = Files.newInputStream(path)) {
  return new String(in.readAllBytes(), StandardCharsets.UTF_8);
}

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?
What production issues show up and how do you diagnose them?