JDK 19: The new features in Java 19

Java Improvement Package 19, thanks this September, is now attribute-full, possessing just reached an original rampdown period. 7 options focus on the release such as structured concurrency, file styles, a preview of a foreign operate and memory API, and guidance for the open resource Linux/RISC-V instruction set architecture (ISA).

With this most recent milestone in the release course of action for standard Java, other planned capabilities such as universal generics and price objects will have to hold out for a afterwards variation of the system. JDK 19 follows the March 22 arrival of JDK 18. Regular Java is on a six-month launch cadence.

JDK 19 is slated to be officially introduced for creation use on September 20, preceded by a 2nd rampdown period commencing July 21, and launch candidates to be published August 11 and August 25. Early access builds of JDK 19 can be accessed from jdk.java.internet/19. The JDK 19 attributes contain:

• Structured concurrency, in an incubator section, is intended to simplify multithreaded programming by a structured concurrency library. This concurrency treats several jobs managing in different threads as a solitary unit of work, to streamline mistake managing and cancellation. Trustworthiness and observability are improved.
• A preview of history styles, to deconstruct report values. Report styles and variety styles can be nested to permit a declarative, highly effective, and composable form of information navigation and processing. Aims of the proposal include things like extending pattern matching to specific additional complex, composable information queries while not altering the syntax or semantics of type patterns. This proposal builds on sample matching for instanceof, delivered in JDK 16  in March 2021. Long term plans could simply call for history styles to be extended with capabilities this sort of as array styles and vararg patterns. Report styles is portion of Project Amber, an hard work to discover and incubate scaled-down, productivity-oriented Java features.
• A preview of a foreign functionality and memory API, which would introduce an API by which Java programs can interoperate with code and facts outside the house the Java runtime. By successfully invoking foreign features (i.e., code exterior the Java runtime) and safely accessing international memory (i.e., memory not managed by the JVM) the API allows Java applications to phone native libraries and method native details with no the danger and brittleness of the Java Indigenous Interface (JNI). The international perform and memory API combines two before incubating APIs: the international memory accessibility API and the overseas linker API. The overseas functionality and memory API was previously incubated in JDK 17 and reincubated in JDK 18. The proposal’s goals include relieve of use, efficiency, generality, and basic safety.
• A preview of virtual threads, which are lightweight threads that drastically decrease the work of creating, preserving, and observing higher-throughput, concurrent purposes. Goals include things like enabling server apps published in the basic thread-per-ask for design to scale with close to-optimal hardware utilization, enabling current code that makes use of the java.lang Thread API to undertake virtual threads with small alter, and enable troubleshooting, debugging, and profiling of digital threads with present JDK instruments. It is not a intention of this proposal to alter the essential concurrency design in Java or supply a new data parallelism assemble in either the Java language or Java libraries. Nor is it a goal to take away the classic implementation of threads or to silently migrate current applications to use digital threads.
• A 3rd preview of pattern matching for swap expressions and statements, extending pattern matching to swap, to make it possible for an expression to be analyzed from a number of patterns, every single with a specific motion, so complicated details-oriented queries can be expressed concisely and properly. This capacity earlier was previewed in JDK 17 and JDK 18. The 3rd preview would incorporate refinements which include the alternative of guarded styles with when clauses in swap blocks. Also, the runtime semantics of a pattern switch when the value of the selector expression is null are much more closely aligned with legacy change semantics. The plan’s plans involve increasing the expressiveness and applicability of swap expressions and statements by permitting patterns to look in situation labels. Other goals consist of allowing developers to take it easy the historic null-hostility of switch when desired, increasing the safety of switch statements and making certain that present swap expressions and statements carry on to compile with no variations and execute with similar semantics.
• A fourth incubation of a vector API that would express vector computations that reliably compile at runtime to best vector recommendations on supported CPU architectures, therefore achieving performance top-quality to equal scalar computations. Builders working with the API get a way to compose intricate vector algorithms in Java, employing the HotSpot car-vectorizer but with a person model that will make vectorizations far more predictable and strong. The vector API beforehand was incubated into JDK 16, JDK 17, and JDK 19.
  Improvements to the API proposed for JDK 19 incorporate enhancements to load and retail store vectors to and from MemorySegments, as outlined by the International Functionality and Memory API preview. JDK 19 would also incorporate two cross-lane vector operations, compress and expand, together with a complementary vector mask compress operation. The compress vector procedure maps lanes of a supply vector, picked by a mask, to a location vector in lane purchase, whilst the grow operation does the inverse. The compress procedure is beneficial in filtering question success.
  In yet another addition to the vector API, bitwise integral lanewise functions would be expanded, like functions such counting the variety of one particular bits, reversing the buy of bits, and compressing and growing bits. Ambitions of the API incorporated currently being obvious and concise, system-agnostic, possessing dependable runtime and compilation performance on x64 and AArch64 architectures, and enabling “graceful” degradation, for predicaments in which a vector computation simply cannot be totally expressed at runtime as a sequence of vector operations.
• With the Linux/RISC-V port, Java would get help for a hardware instruction set that is now supported by a large array of language toolchains. RISC-V basically is a household of associated ISAs. The Linux/RISC-V port would only support the RV64GV configuration of RISC-V, a general reason 64-bit ISA that consists of vector instructions. The developers of Java could contemplate other RISC-V configurations in the foreseeable future.

The port would support the next HotSpot VM selections: the template interpreter, C1 (consumer) JIT compiler, C2 (server) JIT compiler, and all present mainline rubbish collectors which include ZGC and Shenandoah. The actual porting is just about full the emphasis of the JDK Improvement Proposal (JEP) is integration of the port into the JDK mainline repository.

Like JDK 18, JDK 19 is due to be a quick-phrase release, with only six months of best-amount, Leading help.

The preceding release, JDK 17, was a Prolonged Phrase Support (LTS) launch, with many years of support. It arrived September 14, 2021.