Java: HashMap iteration order and when it matters

asked 15 days ago370 viewsen

1

I rely on the iteration order of a HashMap and a colleague says that's a bug. When should I use LinkedHashMap or TreeMap instead?

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asked 15 days ago

3 Answers

7
Accepted answer

With ~2000 examples: start with cross-validation (5-fold), strong regularization (dropout / weight decay), and early stopping. Then data augmentation. Prefer a small model or fine-tune a pretrained one rather than training from scratch.

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answered 15 days ago
6

Biggest wins in order: (1) bundle with esbuild and tree-shake to shrink the artifact, (2) move heavy init out of the handler, (3) provisioned concurrency for latency-critical paths. Runtime choice matters less than bundle size.

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answered 15 days ago
5

HashMap order is unspecified and can change between JVM versions. Use LinkedHashMap for insertion order, TreeMap for sorted keys. Relying on HashMap order is a real bug.

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answered 15 days ago

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