adamkulawik / Java11

Showcase of Java11, 12 and 13 API, lib and syntax novelties including previews

About repo

Repo is a showcase of Java 11, 12 and 13 syntax and API novelties.

benchmark package

In benchmark package I tried to compare new lines() and repeat() method in String class with simpler and more naive approaches.

IMPORTANT Be aware, that this is sample for my learning/fun purpose, not full, professional benchmark of those features. Don't rely on it for any performance-critical low-latency applications; and I don't take any responsibility for that. If you need such a benchmark for significant technical decision consider preparing something better on your own.

demo package

In java11.demo package you can find examples that were used on Silesia JUG flashtalk 22th February 2019.

They are focused to show API details as clear as possible during talk, so neither static imports nor local type inference is used there

In java12.demo and java13.demo there are samples for Java 12 and 13 novelties respectively.

I used all this packages while preparing my talk on JDD 2019 about Java 11, 12 and 13 new stuff.

example package

Package java11.examples contains more examples that were not intended for a quick meet up demo - there are more cases presented there.

known issues

Despite setting --enable-preview flag in maven pom.xml file IntelliJ Idea tends not to set this setting properly in project SDK setup, so this has to be done manually. If you come up a solution, consider submitting a PR, please :)

More about Java 11 novelties

Files

static String readString​(Path path)

static String readString​(Path path, Charset cs)

static Path writeString​(Path path, CharSequence csq, OpenOption... options)

static Path writeString​(Path path, CharSequence csq, Charset cs, OpenOption... options)

JDK Issue: https://bugs.openjdk.java.net/browse/JDK-8201276

Read more: https://dzone.com/articles/new-jdk-11-files-methods-for-readingwriting-string

String

Read more: https://dzone.com/articles/new-methods-on-java-strings-with-jdk-11

Also worth reading: https://4comprehension.com/java-11-string-api-updates/

Regarding Unicode - related issue you HAVE TO and WANT TO watch this amazing talk (available in Polish, but you may try to look for English version) https://youtu.be/QIEpZ0MGoBc

boolean isBlank()

JDK Issue: https://bugs.openjdk.java.net/browse/JDK-8200437

String strip()

String stripLeading()

String stripTrailing()

JDK Issue: https://bugs.openjdk.java.net/browse/JDK-8200378

Stream lines()

JDK Issue: https://bugs.openjdk.java.net/browse/JDK-8200425

String repeat(int count)

JDK Issue: https://bugs.openjdk.java.net/browse/JDK-8198296

To get more details you must read the excellent in-depth explanation https://medium.com/@ggajos/java-11-how-string-repeat-was-implemented-and-why-d93796b7abba

Optional

boolean isEmpty()

Read more: https://dzone.com/articles/optionalisempty-available-in-jdk-11-ea-builds https://www.javacodegeeks.com/2018/04/optional-isempty-coming-to-java.html

JDK Issue: https://bugs.openjdk.java.net/browse/JDK-8184693

Predicate

static Predicate not​(Predicate<? super T> target)

Read more: https://dzone.com/articles/predicatenot-coming-to-java

JDK Issue: https://bugs.openjdk.java.net/browse/JDK-8203428

Pattern

Predicate asMatchPredicate()

JDK Issue: https://bugs.openjdk.java.net/browse/JDK-8201308

TimeUnit

long convert​(Duration duration)

JDK Issue: https://bugs.openjdk.java.net/browse/JDK-8204375

You might also want to get some background of that change in this interesting mail thread: https://openjdk.markmail.org/thread/ndcwjnmbpwhkvkwe#query:+page:1+mid:syazdg3cfd6bbxbk+state:results

JEP 323: Local-Variable Syntax for Lambda Parameters

JEP: http://openjdk.java.net/jeps/323

JEP 321: HTTP Client (Standard)

JEP: https://openjdk.java.net/jeps/321

Read more: https://openjdk.java.net/groups/net/httpclient/intro.html

You might want to see excellent example of usage of this client: https://github.com/jgprogram/sjug-httpclient

When using async mode, please be aware of that issue: https://www.javaspecialists.eu/archive/Issue271.html

More about Java 12 novelties

JEP 326 - Raw String Literals (preview)

JEP description: http://openjdk.java.net/jeps/326

Brian Goetz's mail explaining why the feature had been dropped in favour of Text Blocks: https://mail.openjdk.java.net/pipermail/jdk-dev/2018-December/002402.html

JEP 325 - Switch expressions (preview)

JEP description: https://openjdk.java.net/jeps/325

Note: in this repo only Switch expressions compliant with Java 13 is presented, as it's been changed in Java 13, therefore 12's and 13's switchs are not backward compatible.

Collector

public static <T, R1, R2, R> Collector<T, ?, R> teeing(Collector<? super T, ?, R1> downstream1, Collector<? super T, ?, R2> downstream2, BiFunction<? super R1, ? super R2, R> merger)

Seems terrryfing, huh? In fact it is not.

JDK Issue: https://bugs.openjdk.java.net/browse/JDK-8209685

You might also want to read great explantation there: https://4comprehension.com/a-new-jdk12-stream-api-collector-collectorsteeing/

and there: https://dzone.com/articles/java-12-the-teeing-collector

String

public String indent(int count)

JDK issue: https://bugs.openjdk.java.net/browse/JDK-8200435

Internally indent uses lines() and repeat() from Java 11

More about Java 13 novelties

JEP 354 - Switch Expressions (Preview)

JEP: https://openjdk.java.net/jeps/354

JEP 355 - Text Blocks (Preview)

JEP: https://openjdk.java.net/jeps/355