Java 9, 10 , 11 - e l’ultimissimo 12 - sono arrivati in fretta e hanno portato cambiamenti profondi: nuove funzionalità, strumenti aggiuntivi e jvm. Gli aggiornamenti pubblici di Java 8 sono terminati a gennaio 2019 e questo è uno dei motivi principali che ci porta a guardare alla fase successiva. Theodor Dumitrescu, Java Developer di ThinkOpen, mostra perché la portabilità di un progetto per l'utilizzo di JDK 9 (o superiori) non è immediata come in passato. Viene dedicato un approfondimento specifico al passaggio da Oracle a Eclipse, una sfida non solo per gli sviluppatori ma anche per l'intera community. Infatti, tantissimi progetti hanno cambiato casa abbandonando la ben nota madre Oracle per essere accolti dalla comunità di Eclipse. Lo speaker illustra l’evoluzione dell'intero ecosistema e delle licenze che permettono di sfruttarlo.

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a cura di Theodor Augustin Dumitrescu
Pleased to meet you
JDK Technical Roadmap and Licenses
Highlights JDK 9
Highlights JDK 10
Highlights JDK 11
Highlights JDK 12
OpenJDK Projects
Questions

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WHOAREWE?
00 - Pleased to meet you

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00 - Theodor Augustin Dumitrescu
00

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01
JDKTechnicalRoadmapandLicenses
01.1 - JDK Technical Roadmap
01.2 - JDKs Greenwood
01.3 - Which JDK Binary
01.4 - From JavaEE to JakartaEE

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01.1 - JDK Technical Roadmap
01.1

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01.1 - JDK Technical Roadmap
01.1
Moving Java Forward Faster

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01.1 - JDK Technical Roadmap
01.1
© Oracle

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01.2 - JDKs Greenwood
01.2

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01.3 - Which JDK Binary
01.3 ● java.oralce.com: traditional Oracle binary
○ Oracle Binary Code License
○ FoU restrictions
● jdk.java.net: OpenJDK binary
○ GPLv2 with CPE license
○ Security and bug fix updates only until next JDK release
● adoptopenjdk.net
○ OpenJDK binary based on HotSpot or OpenJ9

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01.3 - Which JDK Binary
01.3
O
Java SE
OpenJDK
Oracle JDK
Java SE
and OpenJDK
Oracle JDK
Before JDK 11 Since JDK 11

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01.4 - From JavaEE to JakartaEE
01.4

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01 - Recaptiluation
01 ● A new LTS release every three years
○ this does not mean three years of free updates
● From JDK 11, the Oracle JDK can only be used in production with a commercial
support contract
○ the only free JDK 11 and later will be OpenJDK binaries
● to receive free updates to the JDK you must update your JDK every six months
● JDK 8 and older are still available completely free
○ but from January, without security patches and bug fixes
○ you have to pay an license for them

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02
02.1 - JMPS
02.2 - Onwards and compatibility
HighlightsJDK9
02.3- Jigsaw
02.4- JEPs

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02.1 - JPMS
02.1
● JEP 220: Modular Run-Time Images
○ 75 OpenJDK modules
■ 27 Java SE modules + 48 JDK modules
○ 99 Oracle JDK
■ 75 + 14 additional + 8 for JavaFX + 2 Oracle specific
● JEP 260: Encapsulate Most Internal APIs
○ ie sun.misc.Unsafe

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02.2 - Onwards and compatibility
02.2
“Clean applications that just depend on java.se should just work”
Oracle

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02.2 JDK 9: the clean Up Starts
● deprecated APIs were removed for the first time
● redundant features eliminated
● significant command line changes
○ removed 187 --XX flags
02.2 - Onwards and compatibility

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02.2
JDK 9: the clean Up Starts
● deprecated APIs were removed for the first time
○ six methods and one class
○ in JDK 11
■ Applets, Browser Plugin, Web Start, JavaFx
■ java.se.ee meta-module
● redundant features eliminated
● significant command line changes
○ removed 187 --XX flags
02.2 - Onwards and compatibility

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02.2
“New versions of Java may include breaking changes” - Oracle
● anything for removal will be deprecated first
○ JEP 277 @Deprecated(forRemoval=true)
○ minimum of one release warning (just six months)
02.2 - Onwards and compatibility

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02.3 - Jigsaw
02.3

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02.3
module module {
requires requires;
exports exports;
}
02.3 - Jigsaw

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02.3
public to everyone
public, but only to specific modules
public only within a module
protected
<package>
private
from JDK9 public != accessible
02.3 - Jigsaw

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02.3
Your App
packages &
classes
JDK/javac
Your App package
distributable
Any JRE/JDK
JVM
Java
packages and
classes
compiles
creates
needs
torun
Pre-JDK9
02.3 - Jigsaw

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02.3
Since JDK9
JDK
Your App
modules
JDK
modules
compiles
JLink creates
JVM
JDK
modules
Your App
modules
02.3 - Jigsaw

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02.4 - JEP 222: jshell
02.4

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02.4 - JEP 213: Milling Project Coin
02.4

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02.4 - JEP 213: Milling Project Coin
02.4

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02.4 - JEP 269: Convenience Factory
Methods for Collections
02.4

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03
HighlightsJDK10
03.1 - JEP 286 Local Variable Type
03.2 - JEPs
03.3 - Docker awareness

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03.1 - JEP 286 Local Variable Type
03.1

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03.2 - JEPs
03.2
● JEP 296: Consolidate JDK forests into single repo
● JEP 304: Garbage Collector Interface (Red Hat)
● JEP 307: Parallel Full GC for G1
● JEP 310: Application Class-Data Sharing
● JEP 312: Thread-Local Handshakes
● JEP 316: Heap allocation on alternative devices (Intel)
● JEP 317: Experimental Java-based JIT compiler (GraalVM)
● JEP 319: Root Certificates

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03.3 - Docker awareness
03.3
● adhering to memory limits set in the container
● setting available cpus in the container
● setting cpu constraints in the container
● -XX:-UseContainerSupport

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04
HighlightsJDK11
04.1 - JEPs
04.1.1 - JEP 318: Epsilon GC
04.1.5 - JEP 330: Launch Single File

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04.1 - JEPs
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● 17 JEPs
● 3 from outside Oracle
○ JEP 315 Red Hat
○ JEP 318 Red Hat
○ JEP 331 Google

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04.1.1 - JEP 318: Epsilon GC
04
● A non-collecting garbage collector
● When memory is exhausted JVM will exit
○ OutOfMemoryExpection
○ Heap dump
● Useful for
○ GC algorithm testing
○ Memory pressure testing
○ Short-lived latency sensitive tasks

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04.1.2 - JEP 321: HTTP Client
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● Incubator module for HTTP/2 support
○ java.net.http module and package
■ HttpClient
■ HttpRequest
■ HttpResponse
■ WebSocket
○ Synchronous and asynchronous

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04.1.3 - JEP 323: Extend Local-Variable
Syntax
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● list.stream().map(s -> s.toString())
● list.stream().map((var s) -> s.toString())
● list.stream().map((@Notnull var s) -> s.toString())

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04.1.4 - JEP 327: Unicode 10 Support
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● 8_518 new characters
○ Bitcoin symbol
○ Nishu
○ Soyombo, Zanabazar Square
● Colbert emoji

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04.1.5 - JEP 330: Launch Single File
Source Code
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● In JDK 10 Three modes for the Java launcher
○ Launch a class file
○ Launch the main class of a JAR file
○ Launch the main class of a module
● Since JDK 11
○ launch a class declared in a source file
■ $ java TopWorkshop.java arg1 argN
○ single file source code shebang
■ #!$JAVA_HOME/bin/java --source 11
■ $ ./TopWorkshop arg1 argN

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04.1.6 - Other JEPs
● JEP 315: Improve Aarch64 intrinsics
● JEP 324: Ket Agreement with Curve25519 and Curve448
● JEP 329: ChaCha20 and Poly1305 Cryptographic Algorithms
● JEP 331: Low-Overhead HEap Profiling
● JEP 332: Transport Layer Security 1.3
● JEP 333: ZGC
● JEP 335: Deprecate the Nashorn JavaScript Engine
● JEP 336: Deprecate the Pack200 Tools and API
04

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● New I/O methods
○ InputStream nullInputStream()
○ OutputStream nullOutputStream()
○ Reader nullReader()
○ Writer nullWriter()
● Optional
○ boolean isEmpty()
● Predicate
○ Predicate not(Predicate)
● Character
○ toString(int)
04
04.1.7 - New API

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04.5
● New String methods
○ inBlack()
○ Stream lines()
○ String repeat()
○ String strip()
○ String stripLeading()
○ String stripTrailing()
04.1.7 - New API

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HighlightsJDK12
05.2 - JEP 325: Switch Expressions
05.1 - JEPs
05.3 - JEP 326: Raw string literals

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05.1 - JEPs
● 189: Shenandoah: A Low-Pause-Time Garbage Collector (Experimental)
● 230: Microbenchmark Suite
● 325: Switch Expressions (Preview)
● 334: JVM Constants API
● 340: One AArch64 Port, Not Two
● 341: Default CDS Archives
● 344: Abortable Mixed Collections for G1
● 346: Promptly Return Unused Committed Memory from G1
05.1

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05.2 - JEP 325: Switch Expressions
T result = switch (arg) {
case L1, L2 -> e1;
case L3 -> e2;
default -> e3;
};
05.2

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05.3 - JEP 326: Raw string literals
var daysInAWeekStr =
"Days in a week n" +
"tttSundayn" +
"tttMondayn" +
"tttTuesdayn" +
"tttWednesdayn" +
"tttThursdayn" +
"tttFridayn" +
"tttSaturdayn";
var daysInAWeekStr = `Days in a week
Sunday
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday`.align();
05.3

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06 OpenJDkProjects
06.2 - Loom: continuations and fibers
06.1 - Amber: rightsizing language ceremony
06.3 - Panama: foreign-function/data interface
06.4 - Valhalla: value types and specialized generics

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06.1 - Project Amber
● JEP 286 Local-Variable Type Inference (var) (JDK 10)
● JEP 301 Enhanced Enums
● JEP 305 Pattern Matching
● JEP 323 Local-Variable Syntax for Lambda Parameters (JDK 11)
● JEP 325 Switch Expressions (preview, JDK 12)
● JEP 326 Raw String Literals
● JEP 348 Java Compiler Intrinsics for JDK APIs
06.1

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06.1 - Project Amber
final class Point {
public final int x;
public final int y;
public Point(int x, int y) {
this.x = x;
this.y = y;
}
// state-based implementations of
equals, hashCode, toString
// nothing else
record Point(int x, int y);
06.1

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06.2 - Project Loom
“The goal of this Project is to explore and incubate Java VM features and APIs built
on top of them for the implementation of lightweight user-mode threads (fibers),
delimited continuations (of some form), and related features, such as explicit
tail-call.” - OpenJDK
06.2

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06.2 - Project Loom
06.2

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06.3 - Project Panama
● native function calling from JVM (C, C++), specifically per JEP 191
○ jextract tool
● native data access from JVM or inside JVM heap
● new data layouts in JVM heap
● native metadata definition for JVM
● header file API extraction tools (see below)
● native library management APIs
● native-oriented interpreter and runtime “hooks”
● class and method resolution “hooks”
● native-oriented JIT optimizations
● tooling or wrapper interposition for safety
● exploratory work with difficult-to-integrate native libraries
06.3

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06.4 - Project Valhalla
● Value Types
● Generic Specialization
● And possibly other related topics
06.4

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(c) @mreinhold
06.4 - Project Valhalla
06.4

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Q&A
07 - Questions?
07