Hunting with Stream Gatherers
summary
Java 24 adds Stream Gatherers as a real extension point to replace collector-only hacks and clumsy intermediate workarounds: an integrator-driven API with supplier/combiner/finisher lets code emit zero‑to‑N elements, suspend, short‑circuit and keep state. Demos include a unique-by-length gatherer replacing nested collectors, sliding/fixed windows and an n‑gram generator that matches Elasticsearch tokenization, plus gather-map-concurrent that uses virtual threads to handle 100 concurrent IO tasks in ≈1s instead of 9s on a 12‑core machine.
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chapters (12)
- 0:00Introduction
- 1:48Upgrading to Java 24
- 5:02Java 8 streams limits
- 10:18Problem with collectors
- 17:19Stream gatherers solution
- 20:54Stream gatherers in Java 24
- 23:44Gatherer interface
- 26:34Built-in gatherers use cases
- 29:02Windowing and palindromes
- 34:39Concurrent mapping with threads
- 39:16N-gram tokenizer
- 43:15Closing
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