277 lines
9.8 KiB
Plaintext
277 lines
9.8 KiB
Plaintext
Key:
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JDK-X - https://bugs.openjdk.java.net/browse/JDK-X
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CVE-XXXX-YYYY: https://cve.mitre.org/cgi-bin/cvename.cgi?name=XXXX-YYYY
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New in release OpenJDK 23.0.0 (2024-09-17):
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===========================================
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Major changes are listed below. Some changes may have been backported
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to earlier releases following their first appearance in OpenJDK 22
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through to 25.
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NEW FEATURES
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============
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Language Features
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=================
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Flexible Constructor Bodies
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============================
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https://openjdk.org/jeps/447
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https://openjdk.org/jeps/482
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In constructors in the Java programming language, allow statements to
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appear before an explicit constructor invocation, i.e., super(..) or
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this(..). The statements cannot reference the instance under
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construction, but they can initialize its fields. Initializing fields
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before invoking another constructor makes a class more reliable when
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methods are overridden.
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This was introduced as a preview language feature
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(http://openjdk.java.net/jeps/12) in OpenJDK 22 (JEP 447) under the
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name "Statements before super(...)". It reaches a second preview in
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OpenJDK 23 (JEP 482) with the addition of allowing fields to be
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initialized before invoking another constructor.
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Unnamed Patterns and Variables
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==============================
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https://openjdk.org/jeps/443
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https://openjdk.org/jeps/456
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Enhance the Java language with unnamed patterns, which match a record
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component without stating the component's name or type, and unnamed
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variables, which can be initialized but not used. Both are denoted by
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an underscore character, _.
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This feature is now final. It was a preview feature
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(http://openjdk.java.net/jeps/12) in OpenJDK 21 (JEP 443).
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Primitive Types in Patterns, instanceof, and switch
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===================================================
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https://openjdk.org/jeps/455
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Enhance pattern matching by allowing primitive type patterns in all
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pattern contexts, and extend instanceof and switch to work with all
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primitive types.
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This is a preview language feature (http://openjdk.java.net/jeps/12)
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introduced in OpenJDK 23 (JEP 455).
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Module Import Declarations
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==========================
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https://openjdk.org/jeps/476
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Enhance the Java programming language with the ability to succinctly
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import all of the packages exported by a module. This simplifies the
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reuse of modular libraries, but does not require the importing code to
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be in a module itself.
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This is a preview language feature (http://openjdk.java.net/jeps/12)
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introduced in OpenJDK 23 (JEP 476).
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Library Features
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================
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Foreign Function & Memory API
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=============================
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https://openjdk.org/jeps/412
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https://openjdk.org/jeps/419
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https://openjdk.org/jeps/424
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https://openjdk.org/jeps/434
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https://openjdk.org/jeps/442
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https://openjdk.org/jeps/454
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Introduce an API by which Java programs can interoperate with code and
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data outside of the Java runtime. By efficiently invoking foreign
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functions (i.e., code outside the JVM), and by safely accessing
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foreign memory (i.e., memory not managed by the JVM), the API enables
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Java programs to call native libraries and process native data without
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the brittleness and danger of JNI.
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This API is now finalised. It was first introduced in incubation
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(https://openjdk.java.net/jeps/11) in OpenJDK 17 (JEP 412), and is an
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evolution of the Foreign Memory Access API (OpenJDK 14 through 16) and
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Foreign Linker API (OpenJDK 16) (see release notes for
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java-17-openjdk). OpenJDK 18 saw a second round of incubation (JEP
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419) before its inclusion as a preview feature
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(http://openjdk.java.net/jeps/12) in OpenJDK 19 (JEP 424). A second
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preview took place in OpenJDK 20 (JEP 434) and a third and final
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preview in OpenJDK 21 (JEP 442).
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Class-File API
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==============
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https://openjdk.org/jeps/457
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https://openjdk.org/jeps/466
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Provide a standard API for parsing, generating, and transforming Java
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class files.
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This is a preview library feature (http://openjdk.java.net/jeps/12)
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introduced in OpenJDK 22 (JEP 457) with a second preview in OpenJDK 23
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(JEP 466).
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Vector API
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==========
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https://openjdk.org/jeps/338
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https://openjdk.org/jeps/414
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https://openjdk.org/jeps/417
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https://openjdk.org/jeps/426
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https://openjdk.org/jeps/438
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https://openjdk.org/jeps/448
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https://openjdk.org/jeps/460
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https://openjdk.org/jeps/469
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Introduce an API to express vector computations that reliably compile
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at runtime to optimal vector hardware instructions on supported CPU
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architectures and thus achieve superior performance to equivalent
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scalar computations.
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This is an incubation feature (https://openjdk.java.net/jeps/11)
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introduced in OpenJDK 16 (JEP 338). A second round of incubation took
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place in OpenJDK 17 (JEP 414), OpenJDK 18 (JEP 417) saw a third,
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OpenJDK 19 a fourth (JEP 426), OpenJDK 20 (JEP 438) a fifth, OpenJDK
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21 a sixth (JEP 448), OpenJDK 22 a seventh (JEP 460) and it reaches
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its eighth in OpenJDK 23 (JEP 469).
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Stream Gatherers
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================
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https://openjdk.org/jeps/461
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https://openjdk.org/jeps/473
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Enhance the Stream API to support custom intermediate operations. This
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will allow stream pipelines to transform data in ways that are not
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easily achievable with the existing built-in intermediate operations.
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This is a preview library feature (http://openjdk.java.net/jeps/12)
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introduced in OpenJDK 22 (JEP 461) with a second preview in OpenJDK 23
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(JEP 473).
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Structured Concurrency
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======================
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https://openjdk.org/jeps/428
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https://openjdk.org/jeps/437
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https://openjdk.org/jeps/453
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https://openjdk.org/jeps/462
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https://openjdk.org/jeps/480
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Simplify multithreaded programming by introducing an API for
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structured concurrency. Structured concurrency treats multiple tasks
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running in different threads as a single unit of work, thereby
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streamlining error handling and cancellation, improving reliability,
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and enhancing observability.
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This API was first introduced in incubation
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(https://openjdk.java.net/jeps/11) in OpenJDK 19 (JEP 428) and had a
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second round of incubation in OpenJDK 20 (JEP 437). It became a
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preview feature (http://openjdk.java.net/jeps/12) in OpenJDK 21 (JEP
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453), reached its second preview in OpenJDK 22 (JEP 462) and has
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a third preview in OpenJDK 23 (JEP 480).
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Implicitly Declared Classes and Instance Main Methods
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=====================================================
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https://openjdk.org/jeps/445
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https://openjdk.org/jeps/463
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https://openjdk.org/jeps/477
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Evolve the Java language so that students can write their first
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programs without needing to understand language features designed for
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large programs. Far from using a separate dialect of Java, students
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can write streamlined declarations for single-class programs and then
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seamlessly expand their programs to use more advanced features as
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their skills grow.
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This library feature was introduced as a preview
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(http://openjdk.java.net/jeps/12) in OpenJDK 21 (JEP 445) under the
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name "Unnamed Classes and Instance Main Methods". It reaches a second
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preview in OpenJDK 22 (JEP 463) and a third in OpenJDK 23 (JEP 477)
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under a new name, due to the move away from unnamed classes to an
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implicitly declared name chosen by the host system.
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Scoped Values
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=============
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https://openjdk.org/jeps/429
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https://openjdk.org/jeps/446
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https://openjdk.org/jeps/464
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https://openjdk.org/jeps/481
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Introduce scoped values, which enable the sharing of immutable data
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within and across threads. They are preferred to thread-local
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variables, especially when using large numbers of virtual threads.
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This API was first introduced in incubation
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(https://openjdk.java.net/jeps/11) in OpenJDK 20 (JEP 429). It became
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a preview feature (http://openjdk.java.net/jeps/12) in OpenJDK 21 (JEP
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446), reached its second preview in OpenJDK 22 (JEP 464) and a third
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in OpenJDK 23 (JEP 481).
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Virtual Machine Enhancements
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============================
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Region Pinning for G1
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=====================
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https://openjdk.org/jeps/423
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Reduce latency by implementing region pinning in G1, so that garbage
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collection need not be disabled during Java Native Interface (JNI)
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critical regions.
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ZGC: Generational Mode by Default
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=================================
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https://openjdk.org/jeps/474
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Switch the default mode of the Z Garbage Collector (ZGC) to the
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generational mode. Deprecate the non-generational mode, with the
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intent to remove it in a future release.
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Tools
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=====
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Launch Multi-File Source-Code Programs
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======================================
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https://openjdk.org/jeps/458
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Enhance the java application launcher to be able to run a program
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supplied as multiple files of Java source code. This will make the
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transition from small programs to larger ones more gradual, enabling
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developers to choose whether and when to go to the trouble of
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configuring a build tool.
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Markdown Documentation Comments
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===============================
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https://openjdk.org/jeps/467
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Enable JavaDoc documentation comments to be written in Markdown rather
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than solely in a mixture of HTML and JavaDoc @-tags.
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DEPRECATIONS
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============
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Deprecate the Memory-Access Methods in sun.misc.Unsafe for Removal
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==================================================================
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https://openjdk.org/jeps/471
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Deprecate the memory-access methods in sun.misc.Unsafe for removal in
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a future release. These unsupported methods have been superseded by
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standard APIs, namely the VarHandle API (JEP 193, OpenJDK 9) and the
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Foreign Function & Memory API (JEP 454, OpenJDK 22). We strongly
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encourage library developers to migrate from sun.misc.Unsafe to
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supported replacements, so that applications can migrate smoothly to
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modern JDK releases.
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REMOVALS
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========
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String Templates
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================
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https://openjdk.org/jeps/430
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https://openjdk.org/jeps/459
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https://openjdk.org/jeps/465
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This was a preview feature (http://openjdk.java.net/jeps/12)
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introduced in OpenJDK 21 (JEP 430) with a second preview in OpenJDK 22
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(JEP 459). A third preview was proposed but ultimately withdrawn for
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OpenJDK 23 (JEP 465) and the feature is no longer present. See [0]
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for further explanation.
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[0] https://mail.openjdk.org/pipermail/amber-spec-experts/2024-April/004106.html
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