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fix links; Java 15: sealed types
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‎README.md

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## Resume by Version
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* [Java 8](java-8/README.md)
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* [Java 8](java-8/)
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* API
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* Stream API
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* Project Lambda
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* Repeating annotations
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* [Java 9](java-9/README.md)
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* [Java 9](java-9/)
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* Milling Project Coin
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* Process API
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* Platform Logging API and Service
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* JShell
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* much more (see JEPs)
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* [Java 10](java-10/README.md) (March 20th, 2018)
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* [Java 10](java-10/) (March 20th, 2018)
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* Process API improvements
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* Collections improvements
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* Application Class-Data Sharing
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* `var` keyword to declare variables
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* [Java 11](java-11/README.md)
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* [Java 11](java-11/)
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* Removal of Java EE Modules, JavaFX and deprecated API
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* Http Client (incubator)
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* var in lambda expressions
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* API improvements
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* Null I/O
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* [Java 12](java-12/README.md)
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* [Java 12](java-12/)
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* Switch expression (preview 1)
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* Compact Number Format
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* Collectors improvements
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* CompletableFuture improvements
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* CDS enable by default
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* New GC and improvements
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* [Java 13](java-13/README.md)
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* [Java 13](java-13/)
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* Switch expression (preview 2)
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* Text blocks
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* String API updates
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* Dynamic CDS Archives
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* ZGC: Uncommit Unused Memory
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* [Java 14](java-14/README.md) (May 17th, 2020)
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* [Java 14](java-14/) (May 17th, 2020)
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* Switch expression (standard)
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* Pattern matching for `instanceof` (preview)
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* Text blocks improvements
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* Records (preview)
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* Helpful NullPointerExceptions
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* Packaging tool
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* JFR even streaming
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* JFR even streaming
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* [Java 15](java-15/)

‎java-11/README.md

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## JEPs
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* [181](https://openjdk.java.net/jeps/336) - Nest-Based Access Control
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* [309](https://openjdk.java.net/jeps/335) - Dynamic Class-File Constants
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* [315](https://openjdk.java.net/jeps/333) - Improve Aarch64 Intrinsics
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* [318](https://openjdk.java.net/jeps/332) - Epsilon: A No-Op Garbage Collector
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* [320](https://openjdk.java.net/jeps/331) - Remove the Java EE and CORBA Modules
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* [321](https://openjdk.java.net/jeps/330) - HTTP Client (Standard)
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* [323](https://openjdk.java.net/jeps/329) - Local-Variable Syntax for Lambda Parameters
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* [324](https://openjdk.java.net/jeps/328) - Key Agreement with Curve25519 and Curve448
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* [181](https://openjdk.java.net/jeps/181) - Nest-Based Access Control
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* [309](https://openjdk.java.net/jeps/309) - Dynamic Class-File Constants
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* [315](https://openjdk.java.net/jeps/315) - Improve Aarch64 Intrinsics
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* [318](https://openjdk.java.net/jeps/318) - Epsilon: A No-Op Garbage Collector
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* [320](https://openjdk.java.net/jeps/320) - Remove the Java EE and CORBA Modules
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* [321](https://openjdk.java.net/jeps/321) - HTTP Client (Standard)
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* [323](https://openjdk.java.net/jeps/323) - Local-Variable Syntax for Lambda Parameters
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* [324](https://openjdk.java.net/jeps/324) - Key Agreement with Curve25519 and Curve448
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* [327](https://openjdk.java.net/jeps/327) - Unicode 10
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* [328](https://openjdk.java.net/jeps/324) - Flight Recorder
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* [329](https://openjdk.java.net/jeps/323) - ChaCha20 and Poly1305 Cryptographic Algorithms
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* [330](https://openjdk.java.net/jeps/321) - Launch Single-File Source-Code Programs
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* [331](https://openjdk.java.net/jeps/320) - Low-Overhead Heap Profiling
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* [332](https://openjdk.java.net/jeps/318) - Transport Layer Security (TLS) 1.3
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* [333](https://openjdk.java.net/jeps/315) - ZGC: A Scalable Low-Latency Garbage Collector (Experimental)
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* [335](https://openjdk.java.net/jeps/309) - Deprecate the Nashorn JavaScript Engine
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* [336](https://openjdk.java.net/jeps/181) - Deprecate the Pack200 Tools and API
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* [328](https://openjdk.java.net/jeps/328) - Flight Recorder
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* [329](https://openjdk.java.net/jeps/329) - ChaCha20 and Poly1305 Cryptographic Algorithms
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* [330](https://openjdk.java.net/jeps/330) - Launch Single-File Source-Code Programs
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* [331](https://openjdk.java.net/jeps/331) - Low-Overhead Heap Profiling
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* [332](https://openjdk.java.net/jeps/332) - Transport Layer Security (TLS) 1.3
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* [333](https://openjdk.java.net/jeps/333) - ZGC: A Scalable Low-Latency Garbage Collector (Experimental)
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* [335](https://openjdk.java.net/jeps/335) - Deprecate the Nashorn JavaScript Engine
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* [336](https://openjdk.java.net/jeps/336) - Deprecate the Pack200 Tools and API
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## Links
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‎java-15/README.md

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# Java 15
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To run each example use: `java --enable-preview --source 15 <FileName.java>`
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## Features
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### Language
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* Sealed types
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* Pattern matching for `instanceof` (second preview)
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* Text blocks (standard)
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* Records (second preview)
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* Integration with sealed types
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### JVM
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## JEPs
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* [339](https://openjdk.java.net/jeps/339) - Edwards-Curve Digital Signature Algorithm (EdDSA)
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* [360](https://openjdk.java.net/jeps/360) - Sealed Classes (Preview)
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* [371](https://openjdk.java.net/jeps/371) - Hidden Classes
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* [372](https://openjdk.java.net/jeps/372) - Remove the Nashorn JavaScript Engine
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* [373](https://openjdk.java.net/jeps/373) - Reimplement the Legacy DatagramSocket API
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* [374](https://openjdk.java.net/jeps/374) - Disable and Deprecate Biased Locking
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* [375](https://openjdk.java.net/jeps/375) - Pattern Matching for instanceof (Second Preview)
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* [377](https://openjdk.java.net/jeps/377) - ZGC: A Scalable Low-Latency Garbage Collector
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* [378](https://openjdk.java.net/jeps/378) - Text Blocks
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* [379](https://openjdk.java.net/jeps/379) - Shenandoah: A Low-Pause-Time Garbage Collector
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* [381](https://openjdk.java.net/jeps/381) - Remove the Solaris and SPARC Ports
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* [383](https://openjdk.java.net/jeps/383) - Foreign-Memory Access API (Second Incubator)
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* [384](https://openjdk.java.net/jeps/384) - Records (Second Preview)
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* [385](https://openjdk.java.net/jeps/385) - Deprecate RMI Activation for Removal
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## Links
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* [JDK 15 Jeps](https://openjdk.java.net/projects/jdk/15/)
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* [Doc about record and sealed types](https://cr.openjdk.java.net/~briangoetz/amber/datum.html)

‎java-15/SealedTypesExample.java

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/**
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* To run: `java --enable-preview --source 15 SealedTypesExample.java`
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*/
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public class SealedTypesExample {
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public static void main(String[] args) {
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// get something from somewhere
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var player = new Player();
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var entity = player.getCollidingEntity();
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switch (entity) {
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case Player:
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player.move();
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entity.move();
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break;
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case Enemy:
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player.die();
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break;
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case Object:
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object.move();
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break;
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// we dont need to do this (nor ifs) - because we restricted the implementations types (we know them)
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// default:
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// throw IllegalStateException("Unexpected entity");
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}
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}
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}
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/**
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* Sealed types will help us to restrict which types can extend/implement a type.
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* Will allow us to write less verbose polymorphic code.
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*/
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sealed abstract class GameEntity
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permits Player, Enemy, Object {}
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class Player extends GameEntity {
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/**
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* Returns the entity which is colling with the player.
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*/
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public GameEntity getCollidingEntity() {
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// obscure logic
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return new Enemy();
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}
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}
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class Enemy extends GameEntity {}
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class Object extends GameEntity {}

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