JDK 19: The new features in Java 19


Java Development Kit 19, owing this September, is now feature-finish, possessing just attained an original rampdown period. Seven functions goal the launch including structured concurrency, report patterns, a preview of a overseas operate and memory API, and guidance for the open resource Linux/RISC-V instruction established architecture (ISA).

With this most recent milestone in the launch approach for standard Java, other planned capabilities this kind of as universal generics and price objects will have to hold out for a later version of the platform. JDK 19 follows the March 22 arrival of JDK 18. Standard Java is on a 6-thirty day period release cadence.

JDK 19 is slated to be officially launched for output use on September 20, preceded by a second rampdown period starting July 21, and release candidates to be released August 11 and August 25. Early access builds of JDK 19 can be accessed from jdk.java.web/19. The JDK 19 features consist of:

  • Structured concurrency, in an incubator stage, is meant to simplify multithreaded programming by means of a structured concurrency library. This concurrency treats a number of duties functioning in distinct threads as a single unit of work, to streamline mistake dealing with and cancellation. Reliability and observability are enhanced.
  • A preview of file patterns, to deconstruct record values. Record styles and variety designs can be nested to help a declarative, effective, and composable kind of data navigation and processing. Plans of the proposal include things like extending pattern matching to express more sophisticated, composable details queries though not altering the syntax or semantics of kind patterns. This proposal builds on pattern matching for instanceof, sent in JDK 16  in March 2021. Future options may possibly get in touch with for document patterns to be extended with abilities these kinds of as array styles and vararg styles. File patterns is aspect of Project Amber, an exertion to discover and incubate lesser, productivity-oriented Java options.
  • A preview of a overseas purpose and memory API, which would introduce an API by which Java programs can interoperate with code and knowledge outside the house the Java runtime. By competently invoking overseas features (i.e., code outdoors the Java runtime) and properly accessing international memory (i.e., memory not managed by the JVM) the API permits Java applications to connect with indigenous libraries and process indigenous information without the need of the hazard and brittleness of the Java Indigenous Interface (JNI). The foreign purpose and memory API combines two before incubating APIs: the foreign memory obtain API and the international linker API. The overseas function and memory API was formerly incubated in JDK 17 and reincubated in JDK 18. The proposal’s aims include things like ease of use, general performance, generality, and safety.
  • A preview of digital threads, which are lightweight threads that significantly reduce the energy of crafting, keeping, and observing superior-throughput, concurrent programs. Targets contain enabling server apps composed in the straightforward thread-per-request model to scale with in close proximity to-optimum components utilization, enabling present code that utilizes the java.lang Thread API to undertake digital threads with small adjust, and allow troubleshooting, debugging, and profiling of digital threads with current JDK applications. It is not a goal of this proposal to transform the basic concurrency model in Java or provide a new info parallelism assemble in both the Java language or Java libraries. Nor is it a aim to remove the conventional implementation of threads or to silently migrate present programs to use virtual threads.
  • A 3rd preview of sample matching for swap expressions and statements, extending pattern matching to swap, to make it possible for an expression to be analyzed from a range of designs, just about every with a specific action, so sophisticated details-oriented queries can be expressed concisely and properly. This capacity formerly was previewed in JDK 17 and JDK 18. The third preview would increase refinements which includes the replacement of guarded styles with when clauses in swap blocks. Also, the runtime semantics of a pattern switch when the worth of the selector expression is null are additional closely aligned with legacy change semantics. The plan’s objectives include things like expanding the expressiveness and applicability of switch expressions and statements by allowing styles to appear in case labels. Other targets include things like permitting builders to rest the historic null-hostility of swap when wanted, expanding the protection of change statements and making sure that present swap expressions and statements keep on to compile with no variations and execute with similar semantics.
  • A fourth incubation of a vector API that would categorical vector computations that reliably compile at runtime to optimal vector instructions on supported CPU architectures, therefore achieving overall performance superior to equivalent scalar computations. Builders using the API acquire a way to create sophisticated vector algorithms in Java, employing the HotSpot automobile-vectorizer but with a user product that will make vectorizations a lot more predictable and robust. The vector API earlier was incubated into JDK 16, JDK 17, and JDK 19.
    Advancements to the API proposed for JDK 19 include enhancements to load and shop vectors to and from MemorySegments, as defined by the International Purpose and Memory API preview. JDK 19 would also incorporate two cross-lane vector operations, compress and grow, with each other with a complementary vector mask compress procedure. The compress vector operation maps lanes of a supply vector, chosen by a mask, to a spot vector in lane buy, even though the grow procedure does the inverse. The compress procedure is helpful in filtering query outcomes.
    In yet another addition to the vector API, bitwise integral lanewise operations would be expanded, such as functions these types of counting the number of one particular bits, reversing the purchase of bits, and compressing and growing bits. Plans of the API included becoming very clear and concise, system-agnostic, owning trustworthy runtime and compilation functionality on x64 and AArch64 architectures, and enabling “swish” degradation, for cases in which a vector computation are unable to be absolutely expressed at runtime as a sequence of vector functions.
  • With the Linux/RISC-V port, Java would obtain aid for a hardware instruction set that is already supported by a vast variety of language toolchains. RISC-V basically is a household of relevant ISAs. The Linux/RISC-V port would only help the RV64GV configuration of RISC-V, a normal reason 64-little bit ISA that involves vector directions. The builders of Java may well consider other RISC-V configurations in the upcoming.

The port would support the following HotSpot VM selections: the template interpreter, C1 (customer) JIT compiler, C2 (server) JIT compiler, and all recent mainline rubbish collectors including ZGC and Shenandoah. The genuine porting is virtually total the target of the JDK Enhancement Proposal (JEP) is integration of the port into the JDK mainline repository.

Like JDK 18, JDK 19 is due to be a shorter-time period release, with only six months of best-stage, Premier aid.

The previous release, JDK 17, was a Extended Expression Aid (LTS) release, with various years of assistance. It arrived September 14, 2021.

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