JDK 19: The new features in Java 19

Java Advancement Package 19, because of this September, has just experienced a seventh feature proposed for it: structured concurrency, to simplify multithreaded programming. Structured concurrency joins 6 past capabilities together with report designs, a preview of a overseas operate and memory API, and support for the open supply Linux/RISC-V instruction established architecture (ISA).

JDK 19, or simply Java 19, potentially could host a wide selection of features, ranging from common generics to price objects, in accordance to strategies underway for maximizing Java. JDK 19 would adhere to JDK 18, which arrived March 22. Common Java is on a 6-month launch cadence.

OpenJDK’s builders have released an official release plan for JDK 19, which has it arriving September 20 as a generation launch, preceded by rampdown phases June 9 and July 21, and release candidates to be released August 11 and August 25.

Early accessibility builds of JDK 19 can be accessed from jdk.java.internet/19. Proposed JDK 19 functions include things like:

• Structured concurrency, in an incubator period, is meant to simplify multithreaded programming by a structured concurrency library. This concurrency treats numerous jobs functioning in unique threads as a solitary unit of work, to streamline error managing and cancellation. Reliability and observability are enhanced.
• A preview of document patterns, to deconstruct document values. Document designs and style designs can be nested to permit a declarative, potent, and composable form of knowledge navigation and processing. Objectives of the proposal contain extending sample matching to categorical extra subtle, composable information queries while not changing the syntax or semantics of type styles. This proposal builds on sample matching for instanceof, delivered in JDK 16  in March 2021. Upcoming ideas may well get in touch with for document patterns to be extended with capabilities these types of as array patterns and vararg styles. History patterns is aspect of Project Amber, an effort and hard work to check out and incubate smaller sized, productiveness-oriented Java characteristics.
• A preview of a foreign perform and memory API, which would introduce an API by which Java applications can interoperate with code and information exterior the Java runtime. By efficiently invoking overseas functions (i.e., code exterior the Java runtime) and safely accessing overseas memory (i.e., memory not managed by the JVM) the API allows Java programs to get in touch with indigenous libraries and approach native details without having the risk and brittleness of the Java Indigenous Interface (JNI). The international function and memory API brings together two previously incubating APIs: the international memory access API and the international linker API. The foreign operate and memory API was earlier incubated in JDK 17 and reincubated in JDK 18. The proposal’s ambitions include things like simplicity of use, overall performance, generality, and security.
• A preview of digital threads, which are light-weight threads that substantially cut down the work of crafting, retaining, and observing substantial-throughput, concurrent apps. Goals consist of enabling server applications composed in the very simple thread-for every-ask for fashion to scale with around-best components utilization, enabling current code that uses the java.lang Thread API to undertake virtual threads with small change, and permit troubleshooting, debugging, and profiling of virtual threads with present JDK instruments. It is not a goal of this proposal to improve the fundamental concurrency product in Java or present a new facts parallelism assemble in both the Java language or Java libraries. Nor is it a goal to clear away the traditional implementation of threads or to silently migrate existing apps to use digital threads.
• A third preview of sample matching for switch expressions and statements, extending pattern matching to swap, to permit an expression to be tested against a amount of designs, each with a certain action, so sophisticated information-oriented queries can be expressed concisely and securely. This capacity beforehand was previewed in JDK 17 and JDK 18. The 3rd preview would insert refinements together with the replacement of guarded designs with when clauses in change blocks. Also, the runtime semantics of a pattern change when the price of the selector expression is null are far more intently aligned with legacy switch semantics. The plan’s plans contain expanding the expressiveness and applicability of change expressions and statements by letting designs to surface in case labels. Other aims include permitting developers to chill out the historic null-hostility of switch when preferred, increasing the basic safety of switch statements and making certain that current change expressions and statements go on to compile with no variations and execute with equivalent semantics.
• A fourth incubation of a vector API that would express vector computations that reliably compile at runtime to optimal vector recommendations on supported CPU architectures, thus attaining effectiveness top-quality to equivalent scalar computations. Developers making use of the API get a way to generate complex vector algorithms in Java, working with the HotSpot car-vectorizer but with a user design that would make vectorizations additional predictable and sturdy. The vector API previously was incubated into JDK 16, JDK 17, and JDK 19.
  Improvements to the API proposed for JDK 19 include enhancements to load and store vectors to and from MemorySegments, as outlined by the Foreign Function and Memory API preview. JDK 19 would also include two cross-lane vector operations, compress and develop, collectively with a complementary vector mask compress procedure. The compress vector procedure maps lanes of a supply vector, chosen by a mask, to a location vector in lane purchase, though the expand operation does the inverse. The compress operation is useful in filtering question effects.
  In an additional addition to the vector API, bitwise integral lanewise operations would be expanded, which include functions this kind of counting the range of a person bits, reversing the get of bits, and compressing and increasing bits. Aims of the API bundled being distinct and concise, system-agnostic, obtaining reliable runtime and compilation functionality on x64 and AArch64 architectures, and enabling “graceful” degradation, for predicaments in which a vector computation are not able to be thoroughly expressed at runtime as a sequence of vector functions.
• With the Linux/RISC-V port, Java would get assistance for a components instruction established that is previously supported by a extensive variety of language toolchains. RISC-V essentially is a spouse and children of similar ISAs. The Linux/RISC-V port would only assistance the RV64GV configuration of RISC-V, a basic intent 64-bit ISA that includes vector directions. The developers of Java may perhaps look at other RISC-V configurations in the long run.

The port would guidance the next HotSpot VM alternatives: the template interpreter, C1 (customer) JIT compiler, C2 (server) JIT compiler, and all present mainline garbage collectors including ZGC and Shenandoah. The true porting is almost comprehensive the target of the JDK Enhancement Proposal (JEP) is integration of the port into the JDK mainline repository.

Like JDK 18, JDK 19 is thanks to be a small-phrase release, with only six months of top rated-amount, Leading assistance.

The previous release, JDK 17, was a Prolonged Expression Guidance (LTS) release, with numerous decades of help. It arrived September 14, 2021.