Java Cram Session: Get caught up on the latest Java changes

Todd Ginsberg Principal Developer Netspend @toddginsberg Java Cram Session https://jconf.dev

@ToddGinsberg Who Is This Talk For? • Java developers still
on Java 8

@ToddGinsberg Who Is This Talk For? • Java developers still
on Java 8 • Are overwhelmed by all of the changes

@ToddGinsberg What Are We Covering? • New Java syntax

@ToddGinsberg What Are We Covering? • New Java syntax •
Interesting new libraries

Interesting new libraries • Interesting new methods

Interesting new libraries • Interesting new methods • Strategies for upgrading and keeping up

@ToddGinsberg What Aren’t We Covering? • Bytecode-level changes

@ToddGinsberg What Aren’t We Covering? • Bytecode-level changes • Most
deprecations

deprecations • New libraries and methods that you may not need right away

deprecations • New libraries and methods that you may not need right away • Licensing and Paid Support

The State Of Things

@ToddGinsberg Current State Java 14

@ToddGinsberg Current State Java 14 Java 15 No Longer Supported
Latest and Greatest

@ToddGinsberg Current State Java 14 Java 15 Java 16 No
Longer Supported Latest and Greatest Coming March 2021

@ToddGinsberg No More Major Releases • Six month Feature Releases
only

only • Miss the train? Wait for the next one

only • Miss the train? Wait for the next one • Allows for preview features

only • Miss the train? Wait for the next one • Allows for preview features • Two quarterly patch releases

only • Miss the train? Wait for the next one • Allows for preview features • Two quarterly patch releases • Upgrading is easier

@ToddGinsberg Long Term Support Java 11 Java 17 Still Receiving
Patches Next LTS

Upgrade Strategies

@ToddGinsberg Java Upgrade Strategies A Update to LTS (11) and
stay there until the next LTS (17)

stay there until the next LTS (17) B Update to the latest release as soon as it comes out

stay there until the next LTS (17) B Update to the latest release as soon as it comes out C Stay on Java 8 forever and let your skills atrophy

stay there until the next LTS (17) B Update to the latest release as soon as it comes out

@ToddGinsberg The Rest of the Talk 1 Changes up until
Java 11

@ToddGinsberg The Rest of the Talk 1 Changes up until
Java 11 2 Changes after Java 11

Welcome To Java 11

@ToddGinsberg JPMS (Modules): The Basics • Create a module system…

• And then modularize the JDK itself…

• And then modularize the JDK itself… • And provide tooling so we can create our own modules...

• And then modularize the JDK itself… • And provide tooling so we can create our own modules... • And our own subset runtimes

@ToddGinsberg JPMS (Modules): Recommendation • Don’t worry about it for
now

now • Take advantage of the fact that it made the JVM more organized

now • Take advantage of the fact that it made the JVM more organized • Wait and see what your dependencies do

@ToddGinsberg Where Did The JRE Go? • Java does not
ship with a JRE any more

ship with a JRE any more • Because the JVM is modular, we can create our own task-focused JVMs!

ship with a JRE any more • Because the JVM is modular, we can create our own task-focused JVMs! • Even if we don’t use modules!

@ToddGinsberg jlink + jdeps == Focused JDK MyApp.jar AppDependency1.jar AppDependency2.jar

jdeps

jdeps List of Modules

jdeps List of Modules jlink

jdeps List of Modules jlink JVM

@ToddGinsberg Where Did JavaFX Go? • Removed from the JVM!

@ToddGinsberg Where Did JavaFX Go? • Removed from the JVM!
• Still maintained, don’t panic! https://openjfx.io/

@ToddGinsberg Say Goodbye To...

@ToddGinsberg Say Goodbye To... • Applets

@ToddGinsberg Say Goodbye To... • Applets • Web Start /
JNLP

@ToddGinsberg New! Compact Strings • Java char takes up two
bytes • All Strings are char x2 bytes in Java 8

bytes • All Strings are char x2 bytes in Java 8 0 1 2 3 4 5 6 7 T “Todd” == o d d

bytes • All Strings are char x2 bytes in Java 8 0 1 2 3 4 5 6 7 T “Todd” == o d d 0 1 2 3 T o d d

@ToddGinsberg New Garbage Collector Options • G1GC is the new
default

default • CMS is now deprecated

default • CMS is now deprecated • Epsilon (for testing)

default • CMS is now deprecated • Epsilon (for testing) • ZGC is experimental

@ToddGinsberg Multi-Version Jars

@ToddGinsberg JShell - A Java REPL

@ToddGinsberg Run Single Files Directly

@ToddGinsberg Syntax - Removal of Single Underscore _

@ToddGinsberg Syntax - Removal of Single Underscore ಠ_ಠ

@ToddGinsberg Syntax - Local var public void doSomething() { String
food = "French Fries"; int quantity = 2; }

@ToddGinsberg Syntax - Local var public void doSomething() { var
food = "French Fries"; var quantity = 2; }

@ToddGinsberg Syntax - Local var public void doSomething() { List<Item>
items = new ArrayList<>(); }

items = new ArrayList<Item>(); }

items = new ArrayList<Item>(); for(var item : items) { // ... } }

@ToddGinsberg Syntax - Local var public void doSomething() { try(var
connection = getConnection()) { // ... } }

@ToddGinsberg Syntax - Local var public void doSomething() { //
Yes var connection = getConnection(); var now = LocalTime.now(); }

@ToddGinsberg Syntax - Private Interface Methods interface Something { private
void somePrivateMethod() { // ... } }

@ToddGinsberg Syntax - Private Interface Methods interface Something { private
static void somePrivateMethod() { // ... } }

@ToddGinsberg Library - Unmodiﬁable Collection Shortcuts List<String> list = List.of("A",
"B", "C");

"B", "C"); Set<String> set = Set.of("A", "B", "C");

"B", "C"); Set<String> set = Set.of("A", "B", "C"); Map<String, Integer> map = Map.of("A", 1, "B", 2);

@ToddGinsberg Library - Unmodiﬁable Collection Shortcuts var list = List.of("A",
"B", "C"); var set = Set.of("A", "B", "C"); var map = Map.of("A", 1, "B", 2);

@ToddGinsberg Library - Stream Enhancements numbers // [0,1,2,3,2,1,0] .stream() .takeWhile(it
-> it < 3) // [0,1,2]

@ToddGinsberg Library - Stream Enhancements numbers // [0,1,2,3,2,1,0] .stream() .dropWhile(it
-> it < 3) // [3,2,1,0]

@ToddGinsberg Library - Stream Enhancements numbers .stream() .dropWhile(it -> it
< 3) .collect(Collectors.toUnmodifiableList());

@ToddGinsberg Library - Stream Enhancements numbers .stream() .dropWhile(it -> it
< 3) .collect(Collectors.toUnmodifiableSet());

@ToddGinsberg Library - String Enhancements String sample = "1\n2\n3";

@ToddGinsberg Library - String Enhancements String sample = "1\n2\n3"; sample
.lines() // Stream<String> [1, 2, 3]

@ToddGinsberg Library - String Enhancements String sample = "1\n2\n3"; sample
.lines() // Stream<String> [1, 2, 3] .forEach(System.out::println);

@ToddGinsberg Library - String Enhancements String sample = " sample
";

"; sample.strip() // "sample"

"; sample.strip() // "sample" sample.stripLeading() // "sample "

"; sample.strip() // "sample" sample.stripLeading() // "sample " sample.stripTrailing() // " sample"

@ToddGinsberg Library - String Enhancements someString.isBlank()

@ToddGinsberg Library - String Enhancements String yell = "Kh" +
"a".repeat(5) + "n!"; // "Khaaaaan!"

@ToddGinsberg Library - Collection.toArray(IntFunction) // In Collection.java: default <T> T[]
toArray(IntFunction<T[]> generator)

@ToddGinsberg Library - Collection.toArray(IntFunction) // In Collection.java: default <T> T[]
toArray(IntFunction<T[]> generator) String[] strings = List .of("A", "B", "C") .toArray(String[]::new)

@ToddGinsberg Library - Enhanced Deprecation @Deprecated

@ToddGinsberg Library - Enhanced Deprecation @Deprecated(since = "9", forRemoval =
true)

@ToddGinsberg Library - HttpClient var client = HttpClient.newBuilder() .connectTimeout(Duration.ofSeconds(15)) .version(HttpClient.Version.HTTP_1_1)
.build();

@ToddGinsberg Library - HttpClient var request = HttpRequest.newBuilder() .GET() .uri(URI.create("https://frinkiac.com/api/random"))
.build();

@ToddGinsberg Library - HttpClient String quote = client .send(request, HttpResponse.BodyHandlers.ofString())
.body();

Welcome To Java 15

@ToddGinsberg Say Goodbye To...

@ToddGinsberg Say Goodbye To... • Nashorn Javascript Engine (and tools)

@ToddGinsberg Say Goodbye To... • Nashorn Javascript Engine (and tools)
• CMS GC

@ToddGinsberg New Garbage Collector Options • ZGC • Shenandoah

@ToddGinsberg Better NullPointerException Messages customer.getAddress().getStreet().toUpperCase();

@ToddGinsberg Better NullPointerException Messages customer.getAddress().getStreet().toUpperCase(); Exception in thread "main" java.lang.NullPointerException
at Yikes.main(Yikes.java:42)

@ToddGinsberg Better NullPointerException Messages customer.getAddress().getStreet().toUpperCase(); -XX:+ShowCodeDetailsInExceptionMessages

@ToddGinsberg Better NullPointerException Messages customer.getAddress().getStreet().toUpperCase(); Exception in thread "main" java.lang.NullPointerException:
Cannot invoke "String.toUpperCase()" because the return value of "Address.getStreet()" is null at Yikes.main(Yikes.java:42)

@ToddGinsberg Syntax - Text Blocks String json = "{\n" +
" \"food\": \"French Fries\",\n" + " \"quantity\": 2\n" + "}";

@ToddGinsberg Syntax - Text Blocks String json = """ {
"food": "French Fries", "quantity: 2 } """;

@ToddGinsberg Syntax - Switch Expressions String food = null; switch
(id) { case 1: { food = "French Fries"; break; } case 2: { food = "Doughnuts"; break; } default: { food = "Pizza"; } }

@ToddGinsberg Syntax - Switch Expressions String food = switch (id)
{ case 1 -> "French Fries"; case 2 -> "Doughnuts"; default -> "Pizza"; };

@ToddGinsberg Syntax - Switch Expressions String food = switch (id)
{ case 1: { // Some other work here yield "French Fries"; } case 2: yield "Doughnuts"; default: yield "Pizza"; };

@ToddGinsberg Good News - Enum Limits Increased!

@ToddGinsberg Good News - Enum Limits Increased! ~2740

@ToddGinsberg Good News - Enum Limits Increased! ~2740 ~4100

Here Be Dragons

@ToddGinsberg Syntax - instanceof Pattern Matching (Preview) if(someObject instanceof String)
{ String someString = (String)someObject; doSomethingWithString(someString); }

@ToddGinsberg Syntax - instanceof Pattern Matching (Preview) if(someObject instanceof String
someString) { doSomethingWithString(someString); }

@ToddGinsberg Records (Preview) If we wanted an immutable 2-D Point
we would need to:

we would need to: • Deﬁne a class

we would need to: • Deﬁne a class • With two ﬁelds called x and y

we would need to: • Deﬁne a class • With two ﬁelds called x and y • And an all-arguments constructor

we would need to: • Deﬁne a class • With two ﬁelds called x and y • And an all-arguments constructor • And getters

we would need to: • Deﬁne a class • With two ﬁelds called x and y • And an all-arguments constructor • And getters • And equals()

we would need to: • Deﬁne a class • With two ﬁelds called x and y • And an all-arguments constructor • And getters • And equals() • And hashcode()

we would need to: • Deﬁne a class • With two ﬁelds called x and y • And an all-arguments constructor • And getters • And equals() • And hashcode() • And toString()

@ToddGinsberg Records (Preview) This pattern is VERY common!

@ToddGinsberg Records (Preview) This pattern is VERY common! record Point(int
x, int y) {}

x, int y) {} var point = new Point(1, 2);

x, int y) {} var point = new Point(1, 2); System.out.println("X: " + point.x()); System.out.println("Y: " + point.y());

@ToddGinsberg Records (Preview) record Point(int x, int y) { public
Point { if(x < 0) throw new IllegalArgumentException(); if(y < 0) throw new IllegalArgumentException(); } }

@ToddGinsberg Records (Preview) record Point(int x, int y) { public
Point { if(x < 0) throw new IllegalArgumentException(); if(y < 0) throw new IllegalArgumentException(); } public Point(Point3D other) { this(other.x(), other.y()); } }

@ToddGinsberg Records (Preview) • Records extend java.lang.Record

@ToddGinsberg Records (Preview) • Records extend java.lang.Record • Records are
ﬁnal

final • Record fields are final

final • Record fields are final • Cannot define any more fields

@ToddGinsberg Syntax - Sealed Classes (Preview) sealed interface Message permits
Start, Stop, Timeout {}

Start, Stop, Timeout {} record Start(String serverName) implements Message {} record Stop(String reason) implements Message {} record Timeout(Duration fromNow) implements Message {}

Start, Stop, Timeout {} record Start(String serverName) implements Message {} record Stop(String reason) implements Message {} record Timeout(Duration fromNow) implements Message {} // ERROR! class Restart implements Message {}

@ToddGinsberg Syntax - Sealed Classes (Preview) // Coming in the
future! String logMessage = switch(someMessage) { Start -> "Starting server: " + someMessage.serverName(); Stop -> "Stopping because: " + someMessage.reason(); Timeout -> "Timeout is now: " + someMessage.fromNow(); };

In Conclusion...

@ToddGinsberg Upgrading Past Java 8 • You have one more
“Big Bang”

“Big Bang” • And then it won’t be that bad

“Big Bang” • And then it won’t be that bad • Because you’ll have new toys to play with

“Big Bang” • And then it won’t be that bad • Because you’ll have new toys to play with • And performance improvements every six months!

@ToddGinsberg [email protected] https://todd.ginsberg.com Thank You! Anonymous Feedback!

Todd Ginsberg Principal Developer Netspend @toddginsberg Java Cram Session https://jconf.dev

Java Cram Session: Get caught up on the latest Java changes

Java Cram Session: Get caught up on the latest Java changes

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