JDK 19: New features in Java 19.

An LTS-free release is scheduled for September. Java 19 will feature virtual threads, structured concurrency as well as patterns matching for switch expressions, an API for vectors, and a port for Linux/RISC-V.

Java Development Kit 19, due in September it is now feature-complete after having completed its initial ramp-down phase. Seven new features are scheduled for the release, including recorded concurrency in a structured manner, record patterns and a glimpse of a foreign function , a memory API, as well as support for the open source Linux/RISC V instruction set architecture (ISA).

With this new milestone in the process of releasing standard Java additional capabilities planned such as universal generics or value objects will need to wait until a future release of this platform. JDK 19 comes in the wake of the arrival on the 22nd of March of JDK 18. Standard Java is on a six-month release schedule.

JDK 19 is slated to be released officially for production use on September 20th which will be followed by a ramp-down phase that begins on July 21. Release candidates due to be released in August between August 11 and. Early access versions that are part of JDK 19 can be accessed via jdk.java.net/19. JDK 19 features include: JDK 19 features include:

Structured concurrency, which is in its incubation phase, is designed to ease multithreaded programming by using an organized concurrency library. The concurrency handles the multiple tasks that run in multiple threads as one unit of work. It is designed to make error handling easier and cancellation. The reliability and observability of the system are enhanced.

Record patterns are displayed in a preview that deconstructs the value of records. Type patterns and record patterns can be nested to provide an explicit, robust and comprehensible form of data processing and navigation. The goals of the proposal are the extension of pattern matching to create more sophisticated, flexible data queries without changing the syntax or meaning of types patterns. The proposal is based on the pattern matching feature for instanceof that was which was released in JDK 16 in March 2021. The future plans could require records to be expanded with features such as array patterns and variable patterns. Record patterns is part of Project Amber, an effort to explore and incubate smaller, productivity-oriented Java features.

An overview of an external function as well as a memory API, which will provide an API through which Java programs could interact with code and data that is not part of the Java runtime. Through the efficient use of the functions of foreign origin (i.e. programming outside within the Java runtime) and securely accessing memory from other sources (i.e. memory that isn't controlled in memory that is not managed by the JVM) The API lets Java applications to access native library functions and processes native data, without the risks and fragility that comes with the Java Native Interface (JNI). The memory and foreign function API integrates two previous incubating APIs including the API for foreign memory access along with the Foreign Linker API. The memory and foreign function API was incubated previously with JDK 17 and then re-incubated with JDK 18. The goals of the proposal are the ease of use performance, generality, and security.

A look at virtual threads. These are light threads that drastically simplify the process of creating, maintaining, and monitoring high-throughput, concurrent applications. This includes enabling server-based applications written in the thread-per-request model to scale up with the highest utilization of hardware, allowing existing software that utilizes an API called the java.lang Thread API implement virtual threads in a minimal manner and allow troubleshooting, debugging and the profiling of virtual processes using the existing JDK tools. This is not the intention of this plan to change the fundamental concurrency model used in Java or to introduce a brand new data parallelism concept either in Java or the Java programming language, and Java libraries. It is also not a plan to get rid of the old threads implementation or to completely migrate existing programs to make use of virtual threads.

The third version of the preview for pattern matching in switch expressions as well as statements, which extends pattern matching beyond switch to let an expression be tested against a variety of different patterns. Every pattern is associated with an associated action, so complicated data-related queries can be written concisely and in a safe manner. The capability was first introduced with JDK 17 and JDK 17 along with JDK 18. The third preview is expected to add enhancements, such as replacing guarded patterns by whenever clauses within switch blocks. Furthermore, the runtime meanings of pattern switches where the selector expression is zero are more in line with the old switch semantics. The goals of the project are to increase the scope of expressiveness and the applicability of switch statements and expressions through the inclusion of patterns in the case of labels. Additionally, the plan will allow developers to loosen the null-hostility to switch whenever they wish and enhancing the security of switch statements and making sure that the existing switch statements and expressions remain compliant with no modifications and operate with the same meanings.

A fourth incubation of the vector API, which would allow vector computations that compile during runtime according to optimize vector instructions on supported CPU architectures, thereby getting better performance than equivalent scaler computations. Developers who use the API gain the ability to write sophisticated algorithmic vectors in Java by using the HotSpot auto-vectorizer. However, it is based on a user model that ensures that vectorizations are more predictable and reliable. The vector API was developed as JDK 16, JDK 17, and JDK 16. JDK 17. JDK 19.

Enhancements to the API suggested in JDK 19 include enhancements to store and load vectors into and from MemorySegments as specified by the Foreign Function and Memory API preview. JDK 19 will also introduce two cross-lane vector operations: expanding and compressing, in conjunction with a complementing compressor for vector masks. Compress vector operations map the lanes from a vector source chosen by a mask to an end-point vector in order of lane, while the expand operation performs reverse. The compress operation can be useful to filter query results.

As an additional feature of the vector API Bitwise integral and wise functions could be expanded to include operations like measuring the amount of bits, changing the order of bits, as well as expanding and compressing bits. The objectives that were incorporated into this API included being simple and concise, and platform-independent with reliability in runtime and compiling with x64 as well as AArch64 architectures, as well as allowing "graceful" degradation in instances where the computation of a vector cannot be fully expressed in time of execution as an array that includes vector operation.

With the port Linux/RISC-V, Java will gain support for a hardware instruction set which has been supported already by a broad variety of toolchains for languages. Actually, RISCV is a family of closely related ISAs. The Linux/RISC-V port will only be able to support only the RV64GV configuration of RISC V, which is a general-purpose 64-bit ISA that supports vector instructions. The Java developers Java might consider other RISCV configurations in the near future.

The port should include the following HotSpot VM options that include the template interpreter C1 (client) JIT compiler, C2 (server) JIT compiler, and all mainline garbage collection systems, including ZGC as well as Shenandoah. The actual porting process is almost completed; the main goal on this JDK Enhancement Proposal (JEP) is the integration of this port with the JDK Mainline repository.
As JDK 18 before it, JDK 19 is due to be a temporary release that will only provide six months of top-quality and Premier support.

The prior JDK 17 release, was a long-term support (LTS) release that included many years of service. The release was announced on 14 September 2021.

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