InfoQ Homepage JEP Content on InfoQ
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Java 25 Integrates Compact Object Headers with JEP 519
Java 25 introduces Compact Object Headers (JEP 519), delivering up to 30% CPU savings and reduced memory usage for applications with small objects. This user-friendly feature compresses object headers from 12 bytes to 8, requiring only a JVM flag to activate. Extensively validated by Amazon, it enhances performance, reduces GC pressure, and is ideal for modern cloud deployments.
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Java 25 Introduces Stable Values API for Deferred Immutability and Improved Application Startup
JEP 502 introduces the Stable Values API in JDK 25, enhancing application startup performance by allowing deferred immutability. This feature enables thread-safe, at-most-once initialization of complex objects, combining the best of final fields with lazy initialization. It empowers developers to improve efficiency and reduce initialization pitfalls while leveraging JVM optimizations.
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JEP 505 Delivers Fifth Preview of Java's Structured Concurrency with Key API Refinements
JEP 505, Structured Concurrency, has reached Targeted status in JDK 25. This refined API enhances parallel task management through static factory methods like StructuredTaskScope.open(). It improves cancellation, observability, and subtask lifetime handling, ensuring clearer, safer code. Developers are encouraged to explore and provide feedback on this innovative iteration.
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Instance Main Methods Move from Preview to Final in JDK 25
JEP 512 enhances Java with Compact Source Files and Instance Main Methods in JDK 25, easing the learning curve for beginners. Key features include simplified syntax, automatic imports, and a new IO helper class, empowering developers to create programs with minimal complexity. These changes solidify Java's commitment to accessibility and innovation in programming.
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JEP 481: Third Preview of Scoped Values API Brings Key Enhancements in JDK 23
JEP 481, Scoped Values (Third Preview), formerly known as Extent-Local Variables (Incubator), offers a third preview, with one change, to gain additional experience and feedback from one round of incubation and two rounds of preview. This feature enables the sharing of immutable data within and across threads.
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JEP 456: Preparing for the Removal of Unsafe Memory-Access Methods
JEP 471, Deprecate the Memory-Access Methods in sun.misc.Unsafe for Removal, has been delivered for JDK 23. This JEP proposes to deprecate the memory access methods in the Unsafe class for removal in a future release. These unsupported methods have been superseded by standard APIs: JEP 193, Variable Handles, delivered in JDK 9; and JEP 454, Foreign Function & Memory API, delivered in JDK 22.
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Rampdown Phase One: What's to Expect in JDK 23
As Iris Clark declared, JDK 23 is now in the crucial Rampdown Phase One, a significant milestone in the JDK development process. This phase started on Thursday, June 6, and the Java community eagerly anticipates the new features and enhancements that will be part of this release. This crucial phase marks the transition of changes intended for JDK 23 into the mainline repository.
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JEP 477 Enhances Beginner Experience with Implicitly Declared Classes and Instance Main Methods
JEP 477, Implicitly Declared Classes and Instance Main Methods (Third Preview), has been promoted to Targeted status. This JEP proposes to "evolve the Java language so that students can write their first programs without needing to understand language features designed for large programs." This JEP moves forward Brian Goetz's September 2022 blog post, Paving the on-ramp.
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JEP 467: Java Enhances Documentation with Markdown Support
JEP 467, Markdown Documentation Comments, has been promoted from Proposed to Target to Targeted for JDK 23. This feature proposes to enable JavaDoc documentation comments to be written in Markdown rather than a mix of HTML and JavaDoc @ tags. This will allow for documentation comments that are easier to write and read in source form.
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JEP 476: Simplifying Java Development with Module Import
JEP 476, Module Import Declarations (Preview), was integrated into JDK 23. This preview feature proposes to enhance the Java programming language with the ability to succinctly import all of the packages exported by a module, with the goal of simplifying the reuse of modular libraries without requiring code to be in a module itself.
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Simplifying Java Development: Introducing Multi-File Program Launching
JEP 458, Launch Multi-File Source-Code Programs, has been Closed/Delivered for JDK 22. This JEP proposes to enhance the Java Launcher to execute an application supplied as one or more files of Java source code. This allows a more gradual transition from small applications to larger ones by postponing a full-blown project setup.
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JEP 447: Refining Java Constructors for Enhanced Flexibility
After its review concluded, JEP 447, Statements before super(...) (Preview), was delivered for JDK 22. This JEP, under Project Amber, proposes to allow statements that do not reference an instance being created to appear before super() calls in a constructor and preserve existing safety and initialization guarantees for constructors.
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JEP 457: Streamlining Java Development with the Class-File API
JEP 457, Class-File API (Preview), has been Integrated into JDK 22, proposing a new API for parsing, generating, and transforming Java class files. This API will initially replace ASM within the JDK with plans for a public API. Goetz, the Java language architect at Oracle, described ASM as outdated and provided details on the API's evolution.
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Foreign Function & Memory API to Bridge the Gap between Java and Native Libraries
After its review concluded, JEP 454, Foreign Function & Memory API has been promoted from Targeted to Integrated for JDK 22. This JEP proposes to finalize this feature after two rounds of incubation and three rounds of preview. The API aims to replace traditional, complex methods like JNI, offering a more efficient and secure approach.
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OpenJDK's JEP 451: Balancing Serviceability and Integrity in JVM
JEP 451, Prepare to Disallow the Dynamic Loading of Agents, has been completed from Target status for JDK 21. This JEP has evolved from its original intent to disallow the dynamic loading of agents into a running JVM by default to issue warnings when agents are dynamically loaded into a running JVM.