Java 17 LTS: Enterprise Features Guide

  • 15/12/2021
  • One-minute read
  • Pattern Matching & Sealed Classes: JEP 406 (Pattern Matching for switch – preview) and JEP 409 (Sealed Classes) simplify type-safe hierarchies and eliminate boilerplate instanceof chains.
  • Context-Specific Deserialization Filters (JEP 415): Strengthens protections against serialization gadgets in enterprise applications.
  • Enhanced Pseudo-Random Number Generators (JEP 356): New interfaces and algorithms (L64X128MixRandom, Xoshiro256PlusPlus) enable reproducible simulations and better stream APIs.
  • Strong Encapsulation of JDK Internals (JEP 403): --illegal-access is removed; only critical internal APIs (e.g., sun.misc.Unsafe) remain accessible.
  • Foreign Function & Memory API (JEP 412 – incubator): Early preview of Project Panama for calling native code without JNI.

Upgrade Checklist

  1. Dependency Audit: Ensure frameworks support Java 17; upgrade build tools (Maven/Gradle plugins) accordingly.
  2. Illegal Access Cleanup: Replace reflective access to JDK internals with supported APIs or reactive modules.
  3. Testing: Run unit, integration, and load tests with the new JVM; watch for changes in garbage collectors (G1 default, optional ZGC/Shenandoah).
  4. Runtime Flags: Review startup scripts—many legacy flags were removed or renamed.

Security Considerations

  • Adopt the new strong encapsulation stance; if you must open modules, use scoped --add-opens with clear documentation.
  • Review TLS configurations; obsolete algorithms continue to be deprecated over time.

Resources

javajvmenterprisesecurityprogramming