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Author: NESOY

content/JDK 21.md

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+---
+title: JDK 21
+description:
+aliases: []
+date: 2025-09-05
+tags: [Java, JDK]
+comments: true
+---
+# JDK 21
+## Features
+- 430: String Templates (Preview)
+- 431: Sequenced Collections
+- 439: Generational ZGC
+- 440: Record Patterns
+- 441: Pattern Matching for switch
+- 442: Foreign Function & Memory API (Third Preview)
+- 443: Unnamed Patterns and Variables (Preview)
+- 444: [[Virtual Thread]]
+- 445: Unnamed Classes and Instance Main Methods (Preview)
+- 446: [[ScopedValue]] (Preview)
+- 448: Vector API (Sixth Incubator)
+- 449: Deprecate the Windows 32-bit x86 Port for Removal
+- 451: Prepare to Disallow the Dynamic Loading of Agents
+- 452: Key Encapsulation Mechanism API
+- 453: Structured Concurrency (Preview)
+
+## Reference
+- https://openjdk.org/projects/jdk/21/

content/JDK 25.md

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+---
+title: JDK 25
+description:
+aliases: []
+date: 2025-09-05
+tags: [Java, JDK]
+comments: true
+---
+# JDK 25
+## Features
+- 470: PEM Encodings of Cryptographic Objects (Preview)
+- 502: Stable Values (Preview)
+- 503: Remove the 32-bit x86 Port
+- 505: Structured Concurrency (Fifth Preview)
+- 506: [[ScopedValue]]
+- 507: Primitive Types in Patterns, instanceof, and switch (Third Preview)
+- 508: Vector API (Tenth Incubator)
+- 509: JFR CPU-Time Profiling (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 Profiling
+- 518: JFR Cooperative Sampling
+- 519: Compact Object Headers
+- 520: JFR Method Timing & Tracing
+- 521: Generational Shenandoah
+
+## Reference
+- https://openjdk.org/projects/jdk/25/
+

content/ScopedValue.md

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+---
+title: ScopedValue
+description:
+aliases: []
+date: 2025-09-05
+tags: [Java]
+comments: true
+---
+# ScopedValue
+- Java 21에서 도입된 ScopedValue는 [[ThreadLocal]]의 대안으로, 특정 스레드 컨텍스트 내에서 안전하게 값을 전달할 수 있도록 설계
+- 이는 특히 가변성(mutation) 문제를 피하면서 효율적인 데이터 전달을 가능
+
+## 특징
+- Immutability: 한 번 설정되면 변경할 수 없음
+- Context Bound: 특정 범위(스코프) 내에서만 유효
+- Thread Safety: ThreadLocal과 달리 불변성을 유지하여 동시성 이슈 감소
+- GC 친화적: 불필요한 참조를 남기지 않음
+
+## ThreadLocal 차이
+|     특징      | [[ScopedValue]] | [[ThreadLocal]] |
+| :---------: | :-------------: | :-------------: |
+|    변경 여부    |  Immutability   |     Mutable     |
+|     GC      |    Scope 종료시    |     명시적 제거      |
+| Thread Safe |       없음        |     발생 가능성      |
+
+## Reference
+- https://openjdk.org/jeps/506