Java After 8 - QCon · –Java 8 fixed 1,926 bugs in first 17 months –(1,213 between 6 months and 18 months past GA) §Production use remains on previous version –until newly

© Copyright Azul Systems 2019


@giltene

Java

After 8

Gil Tene

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@giltene

Keeping Up with Java: Look at All These New Features!

Gil TeneCTO, Azul Systems

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@giltene

From JDK 9 To 13And Beyond


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@giltene

Java

After 8

Gil Tene

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@giltene

Java

After 8


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Changes…§ Java 6 2006 (December)

§ Java 7 2011 (July)

§ Java 8 2014 (March)

§ Java 9 2017 (September)

§ Java 10 2018 (18.3)§ Java 11 2018 (18.9)§ Java 12 2019 (19.3)§ Java 13 2019 (19.9)§ Java 14 2020 (20.3) …

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Java version timeline

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Coming up to speed§ “Current” Java is 13, or 11

– Depending on who you talk to

§ Consider changes from your “current” version

§ For most of you, that’s Java 8

§ So need to go over Java 9, 10, 11, 12, 13,…

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Changes…§ Java the language (“Java 13”)

– the syntax, the meaning

§ Java SE the platform (“Java 13”, “JDK 13”, “Java SE 13”)

– specified APIs, packages, behaviour

§ OpenJDK: an implementation (“OpenJDK 13”)– under the hood stuff– garbage collectors, CDS, …

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JDK 9: Big And Small Changes

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Java Platform Module System (JPMS)§ The core Java libraries are now a set of modules (JEP 220)

– 75 OpenJDK modules: § 24 Java SE§ 2 aggregator modules§ 1 smartcard (???)§ 48 JDK

§ Most internal APIs now encapsulated (JEP 260)– sun.misc.Unsafe– Some can be used with command line options

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jlink: The Java Linker (JEP 282)

$ jlink --module-path $JDKMODS:$MYMODS \--addmods com.azul.zapp –-output myimage

$ myimage/bin/java –[email protected]@[email protected]@[email protected]@[email protected]

myimage

…confbin

jlink

lib


JDK 9: The Clean Up Starts§ JDK 9 was a significant change for Java

– Deprecated APIs were removed for the first time§ Six methods and one class§ JDK 10 removed 1 package, 6 classes, 9 methods and 1 field

– Parts of the platform were removed for the first time § The entire java.se.ee aggregator module was “hidden” in JDK 9§ And completely removed in JDK 11

§ JDK 10, 11, 12, 13, 14… continue this work§ More features will be removed in the future

§ CMS GC, Nashorn and Pack200 all deprecated. Others?

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JDK 9 Onwards And Compatibility

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"Clean applications that just depend on java.seshould just work" - Oracle

• Note careful spelling of “java.se”

• ”java.se” refers to an aggregator module in JDK 9+

• Java SE 8 parts are absolutely being removed


Platform parts removed– The java.se.ee aggregator-module

§ java.corba§ java.transaction§ java.activation§ java.xml.bind§ java.xml.ws§ java.xml.ws.annotation

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Compatibility Not Guaranteed§ New versions of Java may include breaking changes

– Anything for removal will be deprecated first– Minimum of one release warning

§ Could be only six months

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JDK 10


Local Variable Type Inference (JEP 286)§ Java gets var

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var userList = new ArrayList<String>(); // infers ArrayList<String>var stream = list.stream(); // infers Stream<String>

for (var name : userList) { // infers String...

}

for (var i = 0; i < 10; i++) { // infers int...

}


var: Clearer try-with-resources

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try (InputStream inputStream = socket.getInputStream();InputStreamReader inputStreamReader = new InputStreamReader(inputStream, UTF_8);

BufferedReader bufferedReader = new BufferedReader(inputStreamReader)) {

// Use bufferedReader}


var: Clearer try-with-resources

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try (var inputStream = socket.getInputStream();var inputStreamReader = new InputStreamReader(inputStream, UTF_8);var bufferedReader = new BufferedReader(inputStreamReader)) {// Use bufferedReader

}


var: Reserved Type (Not Keyword)var var = new ValueAddedReseller();

public class var {public var(String x) {

...}

}

public class Var {public Var(String x) {

...}

}


JDK 10: Selected JEPs§ JEP 286: Local-Variable Type Inference§ JEP 307: Parallel Full GC for G1§ JEP 310: Application Class-Data Sharing§ JEP 317: Experimental Java-based JIT compiler (Graal)§ JEP 316: Heap allocation on alternative devices (Intel)§ JEP 312: Thread-local Handshakes

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JDK 10: APIs§ 73 New APIs

– List, Set, Map.copyOf(Collection)– Collectors

§ toUnmodifiableList§ toUnmodifiableMap§ toUnmodifiableSet

– Optional.orElseThrow()

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JDK 11


323: Extend Local-Variable Syntax§ Local-variable syntax for lambda parameters

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list.stream().map(s -> s.toLowerCase()).collect(Collectors.toList());

list.stream().map((var s) -> s.toLowerCase()).collect(Collectors.toList());

list.stream().map((@Notnull var s) -> s.toLowerCase()).collect(Collectors.toList());


330: Launch Single File Source Code§ JDK 10 has 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

§ JDK 11 adds a forth– Launch a class declared in a source file

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$ java Factorial.java 4


Single File Source Code Shebang

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#!$JAVA_HOME/bin/java --source 11public class Factorial {

public static void main(String[] args) {int n = Integer.parseInt(args[0]);int r = (n == 0) ? 0 : 1;for (int i = 1; i <= n; i++)r *= i;

System.out.println("n = " + n + ", n! = " + r);}

}

$ ./Factorial 4n = 4, n! = 24


JDK 11 Selected JEPs§ 181: Nest-based Access Control§ 309: Dynamic Class-file constants§ 321: HTTP client§ 332: Transport Layer Security (TLS) 1.3§ 333: ZGC: Experimental low-latency garbage collector§ 318: Epsilon garbage collector

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New APIs§ New I/O methods

§ InputStream nullInputStream()§ OutputStream nullOutputStream()§ Reader nullReader()§ Writer nullWriter()

§ Optional§ isEmpty() // Opposite of isPresent

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New APIs§ New String methods

– isBlank()– Stream lines()– String repeat(int)– String strip()– String stripLeading()– String stripTrailing()

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New APIs§ Predicate not(Predicate)

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lines.stream().filter(s -> !s.isBlank())

lines.stream().filter(Predicate.not(String::isBlank))

lines.stream().filter(not(String::isBlank))


JDK 11: Modules Removed– The java.se.ee aggregator-module has been removed

§ java.corba§ java.transaction§ java.activation§ java.xml.bind§ java.xml.ws§ java.xml.ws.annotation

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JDK 12


Switch Expressions§ First preview feature in the OpenJDK

– Not included in the Java SE standard– Preview features require use of ––enable–preview flag

§ Switch construct was a statement– No concept of generating a result that could be assigned

§ Rather clunky syntax– Every case statement needs to be separated– Must remember break (default is to fall through)– Scope of local variables is not intuitive

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Old-Style Switch Statement

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int numLetters;switch (day) {

case MONDAY:case FRIDAY:case SUNDAY:

numLetters = 6;break;

case TUESDAY:numLetters = 7;break;

case THURSDAY:case SATURDAY:

numLetters = 8;break;

case WEDNESDAY:numLetters = 9;break;

default:throw new IllegalStateException("Huh?: " + day); };


New-Style Switch Expression

int numLetters = switch (day) {case MONDAY, FRIDAY, SUNDAY -> 6;case TUESDAY -> 7;case THURSDAY, SATURDAY -> 8;case WEDNESDAY -> 9;default -> throw new IllegalStateException("Huh?: " + day);

};


New Old-Style Switch Expressionint numLetters = switch (day) {case MONDAY:case FRIDAY:case SUNDAY:break 6;

case TUESDAY break 7;

case THURSDAYcase SATURDAYbreak 8;

case WEDNESDAY break 9;

default: throw new IllegalStateException("Huh?: " + day);

};


Switch Expression: Code Blocks

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int levelResult = switch (level) {case 1 -> {var x = computeFrom(level);logger.info("Level 1 alert");break x;

}case 2 -> {var x = negativeComputeFrom(level);logger.info("Level 2 alert");break x;

}default -> throw new IllegalStateException("What level?: " + level);

};


JDK 12: Selected JEPs§ 189: Shenandoah GC (Experimental)§ G1 GC updates

– 344: Abortable mixed collections– 346: Return unused committed memory

§ 334: JVM constant API§ 341: Default CDS archive


Streams§ New collector, teeing

– teeing(Collector, Collector, BiFunction)§ Collect a stream using two collectors§ Use a BiFunction to merge the two collections

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Collector 1

Collector 2

BiFunctionStream Result


Streams

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// AveragingDouble average = Stream.of(1, 4, 5, 2, 1, 7) .collect(teeing(summingDouble(i -> i), counting(),

(sum, n) -> sum / n));


JDK 13


Text BlocksString webPage = """

<html><body>

<p>My web page</p></body>

</html>""";

System.out.println(webPage);

$ java WebPage<html>

<body><p>My web page</p>

</body></html>

$


Switch Expressionint numLetters = switch (day) {case MONDAY:case FRIDAY:case SUNDAY:break 6;

case TUESDAY break 7;

case THURSDAYcase SATURDAYbreak 8;

case WEDNESDAY break 9;


};


Switch Expression (still a preview feature)

int numLetters = switch (day) {case MONDAY:case FRIDAY:case SUNDAY:yield 6;

case TUESDAY yield 7;

case THURSDAYcase SATURDAYyield 8;

case WEDNESDAY yield 9;


};


Switch Expressions

int numLetters = switch (day) {case MONDAY, FRIDAY, SUNDAY -> 6;case TUESDAY -> 7;case THURSDAY, SATURDAY -> 8;case WEDNESDAY -> 9;default -> throw new IllegalStateException("Huh?: " + day);

};


JDK 13: Selected JEPs§ JEP-354: Switch Expressions (Preview)§ JEP-355: Text Blocks (Preview)§ JEP-350: Dynamic CDS Archives§ JEP-351: ZGC (Experimental): Uncommit Unused Memory§ JEP-353: Reimplement the Legacy Socket API



Zulu Community§ OpenJDK is a source code project§ Any binary you run comes from some sort of distro§ Many distros of OpenJDK out there

– Some are well built and well tested– Other are…. Ahem.. Not so much.– E.g. “Mystery meat OpenJDK builds strike again”– Zulu, Corretto, Dragonwell, Liberica, Adopt, etc. etc. etc.– You have plenty of choice…

https://mail.openjdk.java.net/pipermail/jdk8u-dev/2019-May/009330.html


Zulu Community


Zulu§ A FREE, 100% OSS community distribution of OpenJDK

– Certified Java SE compliant, TCK tested, etc.§ JDK 6*, 7, 8, 9, 10, 11, 12, 13, …§ Curated distribution

– Wide platform support:§ Intel 64-bit & 32-bit Windows, Mac, Linux§ ARM 64-bit and 32-bit

– JFR (Java Flight Recorder) and TLS 1.3 support in JDK 8– JDK, JRE, JDK+FX, …

51www.zulu.org


Zulu Community

MTS


The need for version overlap§ Major Java releases take time to stabilize post GA

– huge number of bugs are detected via (post-GA) early adopter exposure

– Java 8 fixed 1,926 bugs in first 17 months– (1,213 between 6 months and 18 months past GA)

§ Production use remains on previous version– until newly GA’ed version matures

§ Production version needs updates during overlap period– security updates, critical fixes, etc.

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Java lifecycle: historic al view

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Java version timeline

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Zulu MTSReleases

Zulu LTSReleases

Zulu Roadmap: LTS and MTS


Zulu Enterprise

§ Zulu with commercial support

§ Releases (LTS, MTS, updates) fit for long term production use

§ Timely updates and security fixes (CPU, PSU, etc.)

§ Includes indemnification, non-Contamination, etc.

§ Used widely across multiple industries

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Select Azul Customers

CONFIDENTIAL | DO NOT DISTRIBUTE 1


Zulu 7, 8, 11, and 13

Azure Spring Cloud


Zulu Enterprise

§ Zulu with commercial support

§ Releases (LTS, MTS, updates) fit for long term production use

§ Timely updates and security fixes (CPU, PSU, etc.)

§ Includes indemnification, non-Contamination, etc.

§ Used widely across multiple industries§ Java 6, 7, 8, 11, 13, …

§ 24x7 support

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Summary

MTS

LTS8

109

11 12

17

1315..

LTS

LTS

..



@gilteneGil TeneCTO, Azul Systems

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Documents

Java After 8 - QCon · –Java 8 fixed 1,926 bugs in first 17 months –(1,213 between 6 months and 18 months past GA) §Production use remains on previous version –until newly