G1 Garbage Collector

Java 27 Arrives with Four Stable Features and Security and Performance Improvements

Java released version 27 on September 15, 2026, bringing nine JEP initiatives, including four stable features: adopting G1 as the default garbage collector in all environments, compact object headers, and a post-quantum-resistant hybrid key exchange. JetBrains confirmed IntelliJ IDEA support for the release from day one.