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Upcoming Java Development Kit release following JDK 26, making G1 the default garbage collector and adding hybrid post-quantum TLS 1.3 key exchange.
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JDK 27 drops the automatic fallback to Serial GC on limited hardware. A JVM in a tight container now gets G1 unless an operator asks for something else, and compact object headers move footprint in the same release.
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Oracle's JDK 27 release notes put hybrid post-quantum key exchange for TLS 1.3 into the default configuration. The migration now belongs to whoever schedules the runtime upgrade.
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JEP 543 proposes finalizing structured concurrency without change, but the last of its seven preview rounds is the one arriving in JDK 27 on September 15. Ahead-of-time code compilation sits at the same Candidate stage.
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JEP 542 is now Targeted for JDK 28, finalising the PEM API after three preview rounds. The final version drops the DEREncodable name, so preview-era code needs one mechanical edit before it compiles again.
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JEP 541 puts macOS/x64 on the deprecation path in JDK 28 while JEP 540 lands a JSON API in incubator. One of those is a dated migration. The other is a prototype.
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The feature list is fixed until the September 15 ship date. Five items are previews you have to ask for; two are HotSpot defaults that apply whether you read the notes or not.
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Two JEPs moved to Proposed to Target for JDK 28: a built-in JSON parsing and generation API that ships as an incubator feature, and formal deprecation of the macOS/x64 port.
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