A fourth incubation of a vector API that would express vector computations that reliably compile at runtime to optimal vector instructions on supported CPU architectures, thus achieving performance superior to equivalent scalar computations.This feature also is part of the Amber project. The hope is to eventually support pattern matching throughout Java, adding it to places where expressions are used. Other goals include allowing developers to relax the historic null-hostility of switch when desired, increasing the safety of switch statements and ensuring that existing switch expressions and statements continue to compile with no changes and execute with identical semantics. The plan's goals include expanding the expressiveness and applicability of switch expressions and statements by allowing patterns to appear in case labels. Also, the runtime semantics of a pattern switch when the value of the selector expression is null are more closely aligned with legacy switch semantics. The third preview would add refinements including the replacement of guarded patterns with when clauses in switch blocks. This capability previously was previewed in JDK 17 and JDK 18. A third preview of pattern matching for switch expressions and statements, extending pattern matching to switch, to allow an expression to be tested against a number of patterns, each with a specific action, so complex data-oriented queries can be expressed concisely and safely.This feature is also part of Project Loom. Nor is it a goal to remove the traditional implementation of threads or to silently migrate existing applications to use virtual threads.

It is not a goal of this proposal to change the basic concurrency model in Java or offer a new data parallelism construct in either the Java language or Java libraries.

Goals include enabling server applications written in the simple thread-per-request style to scale with near-optimal hardware utilization, enabling existing code that uses the java.lang Thread API to adopt virtual threads with minimal change, and enable troubleshooting, debugging, and profiling of virtual threads with existing JDK tools. A preview of virtual threads, which are lightweight threads that dramatically reduce the effort of writing, maintaining, and observing high-throughput, concurrent applications.The proposal's goals include ease of use, performance, generality, and safety. The foreign function and memory API was previously incubated in JDK 17 and reincubated in JDK 18. The foreign function and memory API combines two earlier incubating APIs: the foreign memory access API and the foreign linker API. By efficiently invoking foreign functions (i.e., code outside the JVM) and safely accessing foreign memory (i.e., memory not managed by the JVM) the API enables Java programs to call native libraries and process native data without the danger and brittleness of the Java Native Interface (JNI). A preview of a foreign function and memory API, which would introduce an API by which Java programs can interoperate with code and data outside the Java runtime.Record patterns is part of Project Amber, an effort to explore and incubate smaller, productivity-oriented Java features. Future plans may call for record patterns to be extended with capabilities such as array patterns and vararg patterns. This proposal builds on pattern matching for instanceof, delivered in JDK 16 in March 2021. Goals of the proposal include extending pattern matching to express more sophisticated, composable data queries while not changing the syntax or semantics of type patterns. Record patterns and type patterns can be nested to enable a declarative, powerful, and composable form of data navigation and processing.

A preview of record patterns, to deconstruct record values.

This feature is from Project Loom, which introduced a new lightweight concurrency model. Reliability and observability are improved. This concurrency treats multiple tasks running in different threads as a single unit of work, to streamline error handling and cancellation.

Structured concurrency, in an incubator phase, is intended to simplify multithreaded programming through a structured concurrency API.

The production release follows two release candidates and two rampdown phases, dating back to June.

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