Key features of Java 8 ... 21 release

The changes from Java 8 to Java 21 are vast and cover many areas, including language features, APIs, performance improvements, and more. Here's a high-level summary of key features introduced in each version:

Java 9 (September 2017):

Module System (Project Jigsaw):

Introduces a modular system to make Java scale down to smaller devices. JShell: An interactive Java REPL for testing code snippets rapidly. Stream API Enhancements: Additions to the Stream API, such as the takeWhile, dropWhile, and ofNullable methods. Private Interface Methods: Allows method implementation in interfaces using the private keyword. Java 10 (March 2018):

Local-Variable Type Inference:

Enhances the Java language to introduce var, allowing local variable type inference. Time-Based Release Versioning: New versioning scheme, with a new feature release every six months. Java 11 (September 2018):

HTTP Client API:

Standardized HTTP client API that supports HTTP/2. Local-Variable Syntax for Lambda Parameters: Allows var to be used when declaring the formal parameters of implicitly typed lambda expressions. Flight Recorder: A low-overhead data collection framework for troubleshooting Java applications.

Java 12 (March 2019):

Switch Expressions (Preview):

Extends the switch statement so that it can be used as either a statement or an expression. Compact Number Formatting: Provides more user-friendly number formats.

Java 13 (September 2019):

Text Blocks (Preview):

Adds text blocks, which make it easy to write Java programs that include multi-line string literals. Switch Expressions (Standard): Moves switch expressions from preview to a standard feature. Deep dive into text blocks

Java 14 (March 2020):

Records (Preview):

Introduces records, which are a special kind of class in Java. Pattern Matching for instanceof (Preview): Enhances the Java programming language with pattern matching for the instanceof operator.

Java 15 (September 2020):

Sealed Classes (Preview):

Introduces the sealed classes and interfaces to restrict which other classes or interfaces may extend or implement them. Text Blocks (Standard): Moves text blocks from preview to a standard feature.

Java 16 (March 2021):

Records (Standard):

Moves records from preview to a standard feature.

Pattern Matching for instanceof (Standard):

Moves pattern matching for instanceof from preview to a standard feature.

Java 17 (September 2021):

Sealed Classes (Standard): Moves sealed classes from preview to a standard feature. Strong Encapsulation of JDK Internals: Strongly encapsulates all internal elements of the JDK, except for critical internal APIs.

Java 18 (March 2022), Java 19 (September 2022), Java 20 (March 2023), Java 21 (September 2023):

From Java 18 onwards, each version continues to introduce incremental improvements and new features. Notably, these versions have continued to evolve Project Loom (virtual threads, structured concurrency), Project Panama (improving the connection between Java and native code), and Project Valhalla (value types, primitive classes). Detailed features of these versions would depend on the specific release and the ongoing evolution of these projects.

Please note that this is a summary, and each version also includes numerous smaller features, security enhancements, and performance improvements. The transition from Java 8 to the latest versions marks a significant evolution in Java, adopting a faster, time-based release cycle aimed at delivering smaller feature sets more frequently.

User give summary by key features about Java 18 (March 2022), Java 19 (September 2022), Java 20 (March 2023), Java 21 (September 2023) GPT The following are summaries focusing on key features of Java versions 18 through 21. Note that these features are part of ongoing projects, and not all features might be available for production immediately as some could be released in preview.

Java 18 (March 2022):

Project Loom - Virtual Threads (Preview): Introduces lightweight threads to simplify concurrency in Java applications. Project Panama - Foreign Function & Memory API (Incubator): Aims to improve the connection between Java and native code. Code Snippets in Java API Documentation: Enhances JavaDoc to include pieces of example code, making API documentation more illustrative. Simple Web Server (JEP 408): A command-line tool to start a minimal web server that serves static files, useful for testing, development, and debugging. Pattern Matching for Switch (Preview): Enhances the language to enable pattern matching for switch expressions and statements.

Java 19 (September 2022):

Project Loom - Structured Concurrency (Incubator):

Simplifies multithreaded programming by treating multiple tasks running in different threads as a single unit of work.

Project Panama - Vector API (Second Incubator):

Provides a platform-agnostic vector computation API to express vector computations that compile at runtime to optimal vector instructions.

Foreign Function & Memory API (Second Preview):

Continues to refine the API introduced in Java 17 for interacting with native code and memory.

Record Patterns (Preview):

Enhances the language with record patterns, to deconstruct record values in patterns.

Pattern Matching for Switch (Second Preview):

Continues to refine the pattern matching for switch expressions and statements.

Java 20 (March 2023):

Record Patterns & Array Patterns (Preview):

Introduces patterns for deconstructing records and arrays in instance of expressions and switch statements.

Project Panama - Foreign Function & Memory API (Third Incubator):

Continues the iteration and refinement of APIs for interfacing with native code and memory.

Project Loom - Virtual Threads (Second Preview):

Further refinements to virtual threads, making it easier to write, debug, and maintain concurrent applications in Java.

Pattern Matching for Switch (Third Preview):

Additional refinements to pattern matching in switch expressions and statements.

Java 21 (September 2023):

Sealed Types:

Sealed types are classes or interfaces that restrict which other classes or interfaces may extend or implement them.

Project Loom - Virtual Threads (Standard):

Moves virtual threads from preview to standard feature, aiming to enhance concurrency support in Java.

Project Panama - Foreign Function & Memory API (Standard):

Moves the foreign function and memory API from incubator to standard, allowing better integration with native code.

Pattern Matching for Switch (Standard):

Moves pattern matching for switch from preview to standard, simplifying the coding of complex switch statements.

Project Valhalla - Value Classes (Preview):

Introduces value classes aimed at providing better performance and memory efficiency compared to regular objects. Each of these versions continues Java's trend towards more expressive, safer, and more efficient coding practices. They reflect ongoing projects within the Java community, like Project Loom for concurrency, Project Panama for native integration, and Project Valhalla for value types and generics enhancements.

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