java-27

Java 27

To run each example use: java --enable-preview --source 27 <FileName.java>

JEPs

• 523 - Make G1 the Default Garbage Collector in All Environments
• 527 - Post-Quantum Hybrid Key Exchange for TLS 1.3
• 528 - Post-Mortem Crash Analysis with jcmd
• 531 - Lazy Constants (Third Preview)
• 532 - Primitive Types in Patterns, instanceof, and switch (Fifth Preview)
• 533 - Structured Concurrency (Seventh Preview)
• 534 - Compact Object Headers by Default
• 536 - JFR In-Process Data Redaction
• 537 - Vector API (Twelfth Incubator)
• 538 - PEM Encodings of Cryptographic Objects

Features

• Make G1 the Default Garbage Collector in All Environments
  • HotSpot will use G1 by default
  • G1 will be default GC in all environments when no GC is specified
  • in some scenarios, Serial GC could be selected depending on memory and CPU
    • single CPU or memory less than 1792 MB
• Primitive Types in Patterns, instanceof and switch
  • re-preview without change
• Structured Concurrency
  • re-preview with minor changes
  • changes:
    • added a parameter type in StructuredTaskScope and Joiner to define the exception that can be thrown by join()
    • new static open method in StructuredTaskScope implements the default join policy and uses a given UnaryOperator to produce the StructuredTaskScope configuration
    • Joiner factory methods allSucessfulOrThrow, anySucessfullOrThrow and awaitAllSucessfulOrThrow returns a joiner that throws ExecutionException when the outcome is an exception
    • removed method Joiner.awaitAll
    • method onTimeout from Joiner has been replaced by timeout
• Compact Object Headers by Default
  • compact object headers will be default object header layout in the HotSpot JVM
  • "reduce object headers from 96 bits down to 64 bits on 64-bit architectures, thereby reducing heap size, improving deployment density, and increasing data locality"
  • to disabled: java -XX:-UseCompactObjectHeaders ...
• PEM Encodings of Cryptographic Objects
  • promotion to standard
  • "introduce an API for encoding objects that represent cryptographic keys, certificates, and certificate revocation lists into the widely-used Privacy-Enhanced Mail (PEM) transport format"
  • support conversions between PEM text and cryptographic objects that have standard representations in the binary formats of PKCS#8 (for private keys), X.509 (public keys, certificates, and certificate revocation lists), and PKCS#8 v2.0 (encrypted private keys and asymmetric keys)

Links

• JDK 27 - JEP Dashboard
• JDK 27 JEPs