JDK 10 · JSR 383
JDK 10 is Java SE 10, JSR 383, generally available on 20 March 2018. One language change dominates the release: local-variable type inference. The rest is runtime and platform bookkeeping, including the time-based version numbers used from here on.
var asks the compiler to infer the type of a local variable that has an initializer. It is not allowed for fields, parameters, or method return types.
Java 11 adds var for the parameters of implicitly typed lambdas (JEP 323). That does not extend var to fields.
OpenJDK JEP 286 (leaves JavaMastery)
Related reading: Variables and types
Curriculum file: versions4Java9To11Features.java
G1’s full collection can use multiple threads. This does not change the default collector, which became G1 in Java 9.
OpenJDK JEP 307 (leaves JavaMastery)
Related reading: JVM and memory
Application classes can be stored in a class-data sharing archive, so later runs spend less time loading them.
A Java-based JIT compiler is available as an experimental alternative. It is not the default HotSpot compiler.
Version numbers follow the six-month release train. A feature release is no longer a long list of unrelated milestones.
The shared file demonstrates var, and also Java 9 factories and Java 11 String methods. It requires Java 11. It is not a Java 10 program.
Sources. General availability, JSR 383, and the JEP list: OpenJDK JDK 10. OpenJDK JDK 10 (leaves JavaMastery)