JDK 19: The new features in Java 19


Java Development Kit 19, thanks this September, is now function-finish, owning just arrived at an initial rampdown section. 7 options target the launch including structured concurrency, report patterns, a preview of a international purpose and memory API, and support for the open up resource Linux/RISC-V instruction established architecture (ISA).

With this most recent milestone in the launch procedure for normal Java, other prepared capabilities these kinds of as universal generics and worth objects will have to wait for a afterwards edition of the platform. JDK 19 follows the March 22 arrival of JDK 18. Regular Java is on a 6-thirty day period launch cadence.

JDK 19 is slated to be formally launched for generation use on September 20, preceded by a 2nd rampdown stage beginning July 21, and launch candidates to be printed August 11 and August 25. Early access builds of JDK 19 can be accessed from jdk.java.internet/19. The JDK 19 capabilities incorporate:

  • Structured concurrency, in an incubator stage, is supposed to simplify multithreaded programming by way of a structured concurrency library. This concurrency treats a number of responsibilities functioning in unique threads as a single device of function, to streamline error dealing with and cancellation. Dependability and observability are improved.
  • A preview of document styles, to deconstruct file values. File patterns and sort patterns can be nested to allow a declarative, highly effective, and composable kind of data navigation and processing. Goals of the proposal include things like extending pattern matching to express much more sophisticated, composable knowledge queries even though not shifting the syntax or semantics of type styles. This proposal builds on pattern matching for instanceof, sent in JDK 16  in March 2021. Long run strategies may well call for report styles to be extended with capabilities this kind of as array patterns and vararg designs. File styles is element of Project Amber, an energy to take a look at and incubate smaller sized, efficiency-oriented Java features.
  • A preview of a foreign perform and memory API, which would introduce an API by which Java applications can interoperate with code and information outside the house the Java runtime. By effectively invoking foreign capabilities (i.e., code outside the Java runtime) and properly accessing foreign memory (i.e., memory not managed by the JVM) the API enables Java plans to get in touch with indigenous libraries and course of action native info without having the threat and brittleness of the Java Native Interface (JNI). The foreign operate and memory API combines two before incubating APIs: the overseas memory entry API and the foreign linker API. The international function and memory API was earlier incubated in JDK 17 and reincubated in JDK 18. The proposal’s targets involve ease of use, overall performance, generality, and basic safety.
  • A preview of virtual threads, which are light-weight threads that substantially lower the energy of writing, preserving, and observing high-throughput, concurrent programs. Targets include things like enabling server applications prepared in the easy thread-for every-request style to scale with close to-optimal components utilization, enabling current code that makes use of the java.lang Thread API to adopt virtual threads with nominal alter, and help troubleshooting, debugging, and profiling of virtual threads with present JDK tools. It is not a purpose of this proposal to improve the simple concurrency model in Java or provide a new facts parallelism construct in possibly the Java language or Java libraries. Nor is it a intention to remove the conventional implementation of threads or to silently migrate current apps to use virtual threads.
  • A third preview of sample matching for swap expressions and statements, extending sample matching to swap, to allow an expression to be tested against a variety of styles, each with a precise action, so complicated information-oriented queries can be expressed concisely and securely. This capability formerly was previewed in JDK 17 and JDK 18. The 3rd preview would include refinements such as the substitution of guarded patterns with when clauses in switch blocks. Also, the runtime semantics of a pattern change when the benefit of the selector expression is null are a lot more intently aligned with legacy switch semantics. The plan’s goals consist of increasing the expressiveness and applicability of switch expressions and statements by making it possible for designs to appear in scenario labels. Other goals consist of enabling developers to rest the historic null-hostility of change when preferred, increasing the safety of swap statements and guaranteeing that existing switch expressions and statements proceed to compile with no changes and execute with similar semantics.
  • A fourth incubation of a vector API that would specific vector computations that reliably compile at runtime to optimum vector guidelines on supported CPU architectures, consequently obtaining effectiveness remarkable to equal scalar computations. Developers utilizing the API gain a way to produce intricate vector algorithms in Java, employing the HotSpot automobile-vectorizer but with a user model that helps make vectorizations much more predictable and sturdy. The vector API beforehand was incubated into JDK 16, JDK 17, and JDK 19.
    Enhancements to the API proposed for JDK 19 involve enhancements to load and shop vectors to and from MemorySegments, as defined by the Foreign Perform and Memory API preview. JDK 19 would also increase two cross-lane vector functions, compress and broaden, collectively with a complementary vector mask compress operation. The compress vector procedure maps lanes of a supply vector, selected by a mask, to a place vector in lane get, though the develop operation does the inverse. The compress operation is practical in filtering query outcomes.
    In another addition to the vector API, bitwise integral lanewise functions would be expanded, including functions these kinds of counting the quantity of a person bits, reversing the purchase of bits, and compressing and expanding bits. Objectives of the API bundled staying clear and concise, system-agnostic, acquiring dependable runtime and compilation overall performance on x64 and AArch64 architectures, and enabling “swish” degradation, for conditions in which a vector computation are not able to be completely expressed at runtime as a sequence of vector operations.
  • With the Linux/RISC-V port, Java would gain support for a components instruction established that is already supported by a broad selection of language toolchains. RISC-V in fact is a spouse and children of connected ISAs. The Linux/RISC-V port would only aid the RV64GV configuration of RISC-V, a common intent 64-little bit ISA that involves vector guidance. The developers of Java may well contemplate other RISC-V configurations in the future.

The port would aid the following HotSpot VM possibilities: the template interpreter, C1 (client) JIT compiler, C2 (server) JIT compiler, and all present mainline garbage collectors which include ZGC and Shenandoah. The genuine porting is just about complete the emphasis of the JDK Improvement Proposal (JEP) is integration of the port into the JDK mainline repository.

Like JDK 18, JDK 19 is owing to be a small-time period release, with only 6 months of top rated-level, Premier help.

The previous release, JDK 17, was a Extensive Expression Guidance (LTS) release, with quite a few a long time of support. It arrived September 14, 2021.

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