Language Update Java 櫻庭 祐一 

Java の作り方 https://openjdk.org/projects/jdk/ OpenJDK: JDK Project Mark Reinhold の他のプロジェクトをまとめて を開発 JDK OpenJDK Java 25 2024-09-16 Java 24 2023-03-18 半年ごとのリリース Java 21, Java 25 2 年周期 LTS Oracle は などのディストリビュータによる Note: OpenJDK LTS LTS には と非 の区別はない LTS 

JEP: JDK Enhancement Proposal の機能を規定 JDK 新機能だけでなく、実装改善、機能の削除も含む Preview Standard 正式な機能 の種類 JEP Incubator Experimental 言語仕様関連 VM の実装改良 新しい API ex. Records ex. HTTP Client ex. ZGC 

JEP: JDK Enhancement Proposal の機能を規定 JDK 新機能だけでなく、実装改善、機能の削除も含む Preview Standard 正式な機能 の種類 JEP Incubator Experimental 言語仕様関連 VM の実装改良 新しい API ex. Records ex. HTTP Client ex. ZGC 

Java 22 423: Region Pinning for G1 454: Foreign Function & Memory API 456: Unnamed Variables & Patterns 458: Launch Multi-File Source-Code Programs Java 23 467: Markdown Documentation Comments 471: Deprecate the Memory-Access Methods in sun.misc.Unsafe for Removal 474: ZGC: Generational Mode by Default Java 24 472: Prepare to Restrict the Use of JNI 475: Late Barrier Expansion for G1 479: Remove the Windows 32-bit x86 Port 483: Ahead-of-Time Class Loading & Linking 484: Class-File API 485: Stream Gatherers 486: Permanently Disable the Security Manager 490: ZGC: Remove the Non-Generational Mode 491: Synchronize Virtual Threads without Pinning 493: Linking Run-Time Images without JMODs 496: Quantum-Resistant Module-Lattice-Based Key Encapsulation Mechanism 497: Quantum-Resistant Module-Lattice-Based Digital Signature Algorithm 498: Warn upon Use of Memory-Access Methods in sun.misc.Unsafe 501: Deprecate the 32-bit x86 Port for Removal Java 25 470: PEM Encodings of Cryptographic Objects (Preview) 502: Stable Values (Preview) 503: Remove the 32-bit x86 Port 505: Structured Concurrency (Fifth Preview) 506: Scoped Values 507: Primitive Types in Patterns, instanceof, and switch (Third Preview) 508: Vector API (Tenth Incubator) 509: JFR CPU-Time Pro ling (Experimental) 510: Key Derivation Function API 511: Module Import Declarations 512: Compact Source Files and Instance Main Methods 513: Flexible Constructor Bodies 514: Ahead-of-Time Command-Line Ergonomics 515: Ahead-of-Time Method Pro ling 518: JFR Cooperative Sampling 519: Compact Object Headers 520: JFR Method Timing & Tracing 521: Generational Shenandoah Java 22, 23, 24はStandard JEPのみ 

Java 22 423: Region Pinning for G1 454: Foreign Function & Memory API 456: Unnamed Variables & Patterns 458: Launch Multi-File Source-Code Programs Java 23 467: Markdown Documentation Comments 471: Deprecate the Memory-Access Methods in sun.misc.Unsafe for Removal 474: ZGC: Generational Mode by Default Java 24 472: Prepare to Restrict the Use of JNI 475: Late Barrier Expansion for G1 479: Remove the Windows 32-bit x86 Port 483: Ahead-of-Time Class Loading & Linking 484: Class-File API 485: Stream Gatherers 486: Permanently Disable the Security Manager 490: ZGC: Remove the Non-Generational Mode 491: Synchronize Virtual Threads without Pinning 493: Linking Run-Time Images without JMODs 496: Quantum-Resistant Module-Lattice-Based Key Encapsulation Mechanism 497: Quantum-Resistant Module-Lattice-Based Digital Signature Algorithm 498: Warn upon Use of Memory-Access Methods in sun.misc.Unsafe 501: Deprecate the 32-bit x86 Port for Removal Java 25 470: PEM Encodings of Cryptographic Objects (Preview) 502: Stable Values (Preview) 503: Remove the 32-bit x86 Port 505: Structured Concurrency (Fifth Preview) 506: Scoped Values 507: Primitive Types in Patterns, instanceof, and switch (Third Preview) 508: Vector API (Tenth Incubator) 509: JFR CPU-Time Pro ling (Experimental) 510: Key Derivation Function API 511: Module Import Declarations 512: Compact Source Files and Instance Main Methods 513: Flexible Constructor Bodies 514: Ahead-of-Time Command-Line Ergonomics 515: Ahead-of-Time Method Pro ling 518: JFR Cooperative Sampling 519: Compact Object Headers 520: JFR Method Timing & Tracing 521: Generational Shenandoah Java 22, 23, 24はStandard JEPのみ 宣言的記法 データ指向 VM 初心者向け 安全性 

Java 22 423: Region Pinning for G1 454: Foreign Function & Memory API 456: Unnamed Variables & Patterns 458: Launch Multi-File Source-Code Programs Java 23 467: Markdown Documentation Comments 471: Deprecate the Memory-Access Methods in sun.misc.Unsafe for Removal 474: ZGC: Generational Mode by Default Java 24 472: Prepare to Restrict the Use of JNI 475: Late Barrier Expansion for G1 479: Remove the Windows 32-bit x86 Port 483: Ahead-of-Time Class Loading & Linking 484: Class-File API 485: Stream Gatherers 486: Permanently Disable the Security Manager 490: ZGC: Remove the Non-Generational Mode 491: Synchronize Virtual Threads without Pinning 493: Linking Run-Time Images without JMODs 496: Quantum-Resistant Module-Lattice-Based Key Encapsulation Mechanism 497: Quantum-Resistant Module-Lattice-Based Digital Signature Algorithm 498: Warn upon Use of Memory-Access Methods in sun.misc.Unsafe 501: Deprecate the 32-bit x86 Port for Removal Java 25 470: PEM Encodings of Cryptographic Objects (Preview) 502: Stable Values (Preview) 503: Remove the 32-bit x86 Port 505: Structured Concurrency (Fifth Preview) 506: Scoped Values 507: Primitive Types in Patterns, instanceof, and switch (Third Preview) 508: Vector API (Tenth Incubator) 509: JFR CPU-Time Pro ling (Experimental) 510: Key Derivation Function API 511: Module Import Declarations 512: Compact Source Files and Instance Main Methods 513: Flexible Constructor Bodies 514: Ahead-of-Time Command-Line Ergonomics 515: Ahead-of-Time Method Pro ling 518: JFR Cooperative Sampling 519: Compact Object Headers 520: JFR Method Timing & Tracing 521: Generational Shenandoah Java 22, 23, 24はStandard JEPのみ 宣言的記法 データ指向 VM 初心者向け 安全性 

4つの方向性 宣言的記法/ データ指向 VM 初心者向け 安全性 関数型機能はひと段落 小さなObjectを扱う手法 巨大ヒープ用GCの世代別化 小さなObjectを扱う構造 起動時間短縮 今後導入予定のValue Classの露払い機能 初心者のハードルを下げる 保守できない機能の削除 セキュリティ向上 

小さなObjectを扱う Mutable Huge Object Immutable Small Object Brian Goetz Project Valhalla: Value Class （導入時期未定） Java 25までの露払い機能 JEP 484: バイトコードを操作するAPI JEP 513: オブジェクトの初期化順序の変更 JEP 519: オブジェクトヘッダーのコンパクト化 et al. 

初心者のハードルを下げる お約束の記述をなるべく減らす JEP 512: メインクラスの省略 JEP 511: import文の簡略化 et al. import java.util.stream.IntStream; public class Main { public static void main(String... args) { IntStream.range(0, 10) .forEach( i -> System.out.println("Hello, World")); } } Main.java ? 

初心者のハードルを下げる お約束の記述をなるべく減らす JEP 512: メインクラスの省略 JEP 511: import文の簡略化 et al. void main() { IntStream.range(0, 10) .forEach( i -> IO.println("Hello, World")); } Main.java 

Conclusion 4 つの方向性で発展 Mutable Huge ObjからImmutable Small Objへ 初心者に優しく VMの改良と安全性の向上は永遠に続く 

Language Update Java 櫻庭 祐一