Java 27 shipped in September 2026. It's a non-LTS release, so most production teams will skip it and stay on Java 25 LTS, but a few of the defaults it ships are worth knowing about even if you never install it.
G1 is now the only default GC (JEP 523). Small/constrained JVMs used to silently get Serial GC instead
Object headers shrink from 96 bits to 64 bits, on by default (JEP 534). Real measured savings, not a flat percentage (details below)
TLS 1.3 gets quantum-resistant key exchange, on by default (JEP 527). Zero code changes for most apps
Pattern matching finally works on primitives (JEP 532, 5th preview). switch (int) with guards, no boxing
