Java Features Playground

This repository contains exercises and sample code to practice various Java features, including Java 8 and beyond. Each section provides descriptions of the features along with sample code and exercises to help you learn and master them. JEP: JDK Enhancement Proposal

Java 8 Features - LTS

• Functional Interfaces
• Lambda Expressions
• Method References
• Stream API
• Optional
• CompletableFuture
• Concurrency Enhancement by Steam API
• Some other improvements

Java 9 Features

• Private Method usage in Interface
• Java Platform Module System (JPMS) - Project Jigsaw
• Collection Factory Methods (List.of, Set.of, Map.of)
• Stream API Enhancements (takeWhile, dropWhile, iterate with predicate, ofNullable)
• Try-With-Resources Enhancement
• HTTP Client API (incubator version)
• JShell - Java REPL

Java 10 Features

• Local-Variable Type Inference (var keyword)
• Unmodifiable Collections Enhancements (copyOf methods)
• Optional.orElseThrow() Method
• Stream Collectors for Unmodifiable Collections (toUnmodifiableList, toUnmodifiableSet, toUnmodifiableMap)
• G1 Garbage Collector Improvements
• Application Class-Data Sharing
• Time-Based Release Versioning
• Root Certificates
• Heap Allocation on Alternative Memory Devices
• Thread-Local Handshakes

Java 11 Features - LTS

• String API Enhancements

• isBlank()
• lines()
• strip(), stripLeading(), stripTrailing()
• repeat()

• HTTP Client API (Standardized from Java 9 incubator)
• Nest-Based Access Control
• Running Java Files Without Compilation (java SourceFile.java)
• Local-Variable Syntax for Lambda Parameters (var)
• Collection.toArray(IntFunction) Method
• Optional.isEmpty() Method
• Predicate.not Method
• Epsilon: A No-Op Garbage Collector
• ZGC: A Scalable Low-Latency Garbage Collector (Experimental)

Java 12 Features

• Switch Expressions (Preview) (JEP 325) – switch can now be used as an expression.
• Shenandoah GC (JEP 189) – Low-pause-time garbage collector.
• Microbenchmark Suite (JEP 230) – Built-in benchmarking framework.
• One AArch64 Port, Not Two (JEP 340) – Removed redundant ARM 64-bit ports.
• Default CDS Archives (JEP 341) – Improves startup performance by archiving class metadata.
• JVM Constants API (JEP 334) – API for modeling nominal descriptors of key class-file and runtime artifacts.

Java 13 Features

• Text Blocks (Preview) (JEP 355) – Multi-line string literals using triple quotes (""").
• Switch Expressions (2nd Preview) (JEP 354) – Enhancements to switch as an expression.
• Reimplement Legacy Socket API (JEP 353) – Modernized networking stack.
• Dynamic CDS Archives (JEP 350) – Enhances class data sharing.

Java 14 New Features

Records (Preview) (JEP 359) – Immutable data classes with auto-generated methods. Pattern Matching for instanceof (Preview) (JEP 305) – Removes explicit casting after instanceof checks. Switch Expressions (Final) (JEP 361) – Finalized switch as an expression. Helpful NullPointerExceptions (JEP 358) – More detailed NullPointerException messages. JFR Event Streaming (JEP 349) – Continuous JDK Flight Recorder data streaming. Foreign-Memory Access API (Incubator) (JEP 370) – Efficient access to off-heap memory. Deprecate the Solaris and SPARC Ports (JEP 362) – Marked for removal.

Java 15 New Features

• Sealed Classes (Preview) (JEP 360) – Restricting inheritance for classes/interfaces.
• Text Blocks (Final) (JEP 378) – Officially added multi-line strings.
• Hidden Classes (JEP 371) – Allows runtime-only classes for frameworks.
• Pattern Matching for instanceof (2nd Preview) (JEP 375) – Extended pattern matching.
• Foreign-Memory Access API (2nd Incubator) (JEP 383) – Improved off-heap memory access.
• Deprecate RMI Activation (JEP 385) – Marked Remote Method Invocation (RMI) Activation for removal.
• ZGC: A Scalable Low-Latency GC (JEP 377) – Z Garbage Collector became production-ready.

Java 16 New Features

• Records (Final) (JEP 395) – Officially added immutable data classes.
• Pattern Matching for instanceof (Final) (JEP 394) – Improved type checking.
• Sealed Classes (2nd Preview) (JEP 397) – Further refinements to sealed classes.
• Foreign Linker API (Incubator) (JEP 389) – Simplifies interaction with native code.
• Strongly Encapsulate JDK Internals by Default (JEP 396) – Tightened restrictions on internal APIs.
• Elastic Metaspace (JEP 387) – Reduced memory footprint.
• Vector API (Incubator) (JEP 338) – Introduced SIMD operations for performance boosts.
• Unix-Domain Socket Channels (JEP 380) – Supported inter-process communication.

Java 17 Features - LTS

• Sealed Classes (JEP 409) – Restricts which classes can extend a given class.
• Pattern Matching for Switch (JEP 406) – Enables type-based pattern matching in switch statements.
• New macOS Rendering Pipeline (JEP 382) – Uses Metal API for better graphics performance on macOS.
• Strongly Encapsulated JDK Internals (JEP 403) – Blocks access to JDK internal APIs.
• Foreign Function & Memory API (Incubator) (JEP 412) – Allows calling native code without JNI.
• Text Blocks (Introduced in Java 13, but LTS in Java 17) – Supports multi-line string literals.
• Records (JEP 395) – Provides immutable data carriers with auto-generated methods.
• Deprecations & Removals:
  • Security Manager removed (JEP 411)
  • RMI Activation removed (JEP 407)
  • Applets removed

Java 18 Features

• Simple Web Server (JEP 408) – A lightweight built-in HTTP server for quick testing.
• UTF-8 as Default Charset (JEP 400) – Ensures consistent text encoding across platforms.
• Vector API (JEP 417 - Incubator) – Boosts performance for mathematical and data-intensive operations.
• Foreign Function & Memory API (JEP 419 - Incubator) – Simplifies calling native libraries without JNI.
• Deprecation of Finalization (JEP 421) – finalize() is now deprecated, favor try-with-resources instead.

Java 19 Features

• Virtual Threads (JEP 425 - Preview) – Lightweight, high-performance threads for better concurrency.
• Pattern Matching for switch (JEP 405 - Preview) – More powerful switch statements with type matching.
• Record Patterns (JEP 405 - Preview) – Enables pattern matching for records.
• Foreign Function & Memory API (JEP 424 - Incubator) – Enhances native interop without JNI.
• Structured Concurrency (JEP 428 - Incubator) – Simplifies concurrent programming with better thread management.

Java 20 Features

• Scoped Values (JEP 429 - Incubator) – A safer alternative to ThreadLocal.
• Virtual Threads Improvements (JEP 436 - Second Preview) – More stable virtual threads for concurrency.
• Record Patterns (JEP 432 - Second Preview) – Enhancements to pattern matching for records.
• Pattern Matching for switch (JEP 433 - Fourth Preview) – More flexible and powerful switch.
• Foreign Function & Memory API (JEP 434 - Third Incubator) – Further improvements in native interop.

Java 21 Features - LTS

• Virtual Threads (JEP 444 - Finalized) – Now fully stable for lightweight concurrency.
• Pattern Matching for switch (JEP 441 - Finalized) – Fully supported and enhanced.
• Record Patterns (JEP 440 - Finalized) – No longer in preview, ready for production.
• Sequenced Collections (JEP 431 - New API) – A new interface for ordered data structures.
• Scoped Values (JEP 446 - Preview) – A better replacement for ThreadLocal.

  • Virtual Threads & Scoped Values → 🚀 Biggest impact for concurrency!
  • Pattern Matching & Record Patterns → 🏆 Cleaner and more readable code!
  • Sequenced Collections → ✅ More predictable behavior for ordered collections!

Java 22 Features

• Scoped Values (Second Preview - JEP 429) – A safer alternative to ThreadLocal for sharing data within and across threads.
• Stream Gatherers (Preview - JEP 461) – Simplifies collecting multiple streams of data efficiently.
• Structured Concurrency (Second Preview - JEP 428) – Simplifies multithreaded programming by treating related tasks as a single unit of work.
• Statements Before super() (Preview - JEP 447) – Allows statements before the constructor's super() call.
• Unnamed Variables and Patterns (JEP 443) – Introduces unnamed variables and patterns to ignore parts of patterns.

Java 23 Features

• Primitive Types in Patterns, instanceof, and switch (Preview) – JEP 455
• Markdown Documentation Comments – JEP 467
• Module Import Declarations (Preview) – JEP 476
• Implicitly Declared Classes and Instance Main Methods (Third Preview) – JEP 477
• Scoped Values (Preview) – JEP 429

Java 24 Features

• Generational Shenandoah Garbage Collector (Experimental) – JEP 404
• Compact Object Headers (Experimental) – JEP 450
• Stream Gatherers – JEP 485
• Ahead-of-Time Class Loading & Linking – JEP 483
• Quantum-Resistant Module-Lattice-Based Digital Signature Algorithm – JEP 497