Groovy in the light of Java 8 -- SpringOne2GX 2014

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Stay up-to-date Groovy Weekly Newsletter (Every Tuesday) http://beta.groovy-lang.org/groovy-weekly.html 2

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Stay up-to-date Google+ Groovy Page https://google.com/+groovy 3

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Stay up-to-date Google+ Groovy Community http://bit.ly/g-community 4

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A recurring question… Do we still need Groovy now that we have Java 8? 6

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To those who said no… 7

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But more precisely… • Will Java lambdas replace Groovy closures? • What are the differences between them? ! • Will Groovy support all the new Java 8 language constructs? • lambdas, default methods, method references… ! • How Groovy developers can benefit from Java 8? ! • What does Groovy offer beyond Java 8? 8

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What about redundancy? ! ! ! ! ! • Closures • Traits • Truth & null handling • Functional with collections • Method closures ! ! ! ! ! ! ! • Lambdas • Default methods • Optional • Stream API • Method references 9

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What we’re going to talk about • What’s new in Java 8 • new syntax constructs • new APIs ! • Similar concepts in Groovy • and how they compare or complement ! • What Groovy offers in addition • beyond Java, Groovy adds its own twist! 11

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This is not a Java 8 crash courses with all the details :-)

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This is not a Java 8 crash courses with all the details :-) We want to understand the implications with regards to Groovy

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What’s new in Java 8? ! • New syntax • Streams • Profiles • Security enhancements • JavaFX • Tools • i18n • Date / time API • Nashorn / JavaScript ! ! ! • Pack200 • IO / NIO improvements • New utility classes • JDBC • Networking • Concurrency • JAXP • Hotspot • Java Mission Control 14

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New Java 8 syntax constructs • Lambda expressions • Method references • Static & default methods in interfaces • Repeating annotations • Annotations on types • Improved type inference • Method parameter reflection 16

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Lambda expressions 19 double highestScore = students .filter(Student s -> s.getGradYear() == 2011) .map(Student s -> s.getScore()) .max();

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Lambda expressions 20 double highestScore = students .filter(Student s -> s.getGradYear() == 2011) .map(Student s -> s.getScore()) .max();

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Lambda expressions 20 double highestScore = students .filter(Student s -> s.getGradYear() == 2011) .map(Student s -> s.getScore()) .max(); Coercion into a Predicate « functional interface »

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Lambda expressions 20 double highestScore = students .filter(Student s -> s.getGradYear() == 2011) .map(Student s -> s.getScore()) .max(); There’s no function type!

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Lambda expressions 20 double highestScore = students .filter(Student s -> s.getGradYear() == 2011) .map(Student s -> s.getScore()) .max(); Pipeline being built Single pass!

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Lambda expressions 20 double highestScore = students .filter(Student s -> s.getGradYear() == 2011) .map(Student s -> s.getScore()) .max();

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Lambda expressions 21 double highestScore = students .findAll { it.gradYear == 2011 } .collect { it.score} .max()

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Lambda expressions 21 double highestScore = students .findAll { it.gradYear == 2011 } .collect { it.score} .max() In Groovy, that would be…

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Lambda expressions 21 double highestScore = students .findAll { it.gradYear == 2011 } .collect { it.score} .max() Drawback: intermediary data structures Unless you use iterator variants

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Lambda expressions 21 double highestScore = students .findAll { it.gradYear == 2011 } .collect { it.score} .max()

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The various lambda syntaxes 22 String name -> name.length() ! (int left, int right) -> left + right ! (String left, String sep, String right) -> { System.out.println(left + sep + right) }

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The various lambda syntaxes 22 String name -> name.length() ! (int left, int right) -> left + right ! (String left, String sep, String right) -> { System.out.println(left + sep + right) } One parameter: no parens Expression on right: no curly

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The various lambda syntaxes 22 String name -> name.length() ! (int left, int right) -> left + right ! (String left, String sep, String right) -> { System.out.println(left + sep + right) } Statements require curly braces Return keyword required if non-void returning

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The various lambda syntaxes 22 String name -> name.length() ! (int left, int right) -> left + right ! (String left, String sep, String right) -> { System.out.println(left + sep + right) }

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The various lambda syntaxes 23 name -> name.length() ! (left, right) -> left + right ! (left, sep, right) -> { System.out.println(left + sep + right) }

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The various lambda syntaxes 23 name -> name.length() ! (left, right) -> left + right ! (left, sep, right) -> { System.out.println(left + sep + right) } Clever type inference can help get rid of parameter type declarations

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Closures vs lambdas 24 IntStream.range(1, 100).forEach(s -> System.out.println(s)); ! Files.lines(Paths.get('README.adoc')) .map(it -> it.toUpperCase()) .forEach(it -> System.out.println(it));

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Closures vs lambdas 24 IntStream.range(1, 100).forEach(s -> System.out.println(s)); ! Files.lines(Paths.get('README.adoc')) .map(it -> it.toUpperCase()) .forEach(it -> System.out.println(it)); IntStream.range(1, 100).forEach { println it } ! Files.lines(Paths.get('README.adoc')) .map { it.toUpperCase() } .forEach { println it }

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Beyond: Closure default parameters 25 def mult = { int a, int b = 10 -> a * b } ! assert mult(2, 3) == 6 assert mult(5) == 50

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Beyond: Closure default parameters 25 def mult = { int a, int b = 10 -> a * b } ! assert mult(2, 3) == 6 assert mult(5) == 50 Default value if the parameter is not specified

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Beyond: Duck typing polymorphism 26 def adder = { a, b -> a + b } ! assert adder(100, 200) == 300 assert adder('X', 'Y') == 'XY'

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Beyond: Duck typing polymorphism 26 def adder = { a, b -> a + b } ! assert adder(100, 200) == 300 assert adder('X', 'Y') == 'XY' Works both for numbers and for strings

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Builders

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Builders What would Java lambda builders look like?

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Builders What would Java lambda builders look like? Aren’t Groovy builders more powerful?

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Lambda-based builders uglier and less powerful 28 MarkupBuilder pom = new XmlMarkupBuilder() pom.el("modelVersion", "4.0.0"); pom.el("groupId", "com.github"); pom.el("artifactId", "lambda-builder"); pom.el("version", "1.0-SNAPSHOT"); pom.el("dependencies", () -> { pom.el("dependency", () -> { pom.el("groupId", "junit"); pom.el("artifactId", "junit"); pom.elx("version", "4.11"); }); pom.el("dependency", () -> { pom.el("groupId", "commons-beanutils"); pom.el("artifactId", "commons-beanutils"); pom.elx("version", "1.7.0"); }); });

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Neater Groovy builder! 29 def pom = new PomBuilder().project { modelVersion "4.0.0" groupId "com.github" artifactId "lambda-builder" version "1.0-SNAPSHOT" dependencies { dependency { groupId "junit" artifactId "junit" version "4.11" } dependency { groupId "commons-beanutils" artifactId "commons-beanutils" version "1.7.0" } } }

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Aren’t Groovy builders more readable and lean?

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To those who said no… 31

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Memoization

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Closure and method memoization 33 def fib2 = { long n -> if (n < 2) 1 else call(n - 1) + call(n - 2) }.memoize()

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Closure and method memoization 33 def fib2 = { long n -> if (n < 2) 1 else call(n - 1) + call(n - 2) }.memoize() Closures: memoize()

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Closure and method memoization 33 @Memoized long fib(long n) { if (n < 2) 1 else fib(n - 1) + fib(n - 2) } def fib2 = { long n -> if (n < 2) 1 else call(n - 1) + call(n - 2) }.memoize() Closures: memoize()

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Tail recursion

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Closure and method tail recursion 35 def fact = { n, accu = 1G -> if (n < 2) accu else fact.trampoline(n - 1, n * accu) }.trampoline()

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Closure and method tail recursion 35 def fact = { n, accu = 1G -> if (n < 2) accu else fact.trampoline(n - 1, n * accu) }.trampoline() Closures: Tail recursion with trampoline()

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Closure and method tail recursion 35 @groovy.transform.TailRecursive def fact(n, accu = 1G) { if (n < 2) accu else fact(n - 1, n * accu) } def fact = { n, accu = 1G -> if (n < 2) accu else fact.trampoline(n - 1, n * accu) }.trampoline() Closures: Tail recursion with trampoline()

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Method references 36 button.setOnAction(event -> System.out.println(event));

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Method references 36 button.setOnAction(event -> System.out.println(event)); button.setOnAction(System.out::println);

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Method references — 3 main cases 37 instance::instanceMethod ! SomeClass::staticMethod ! SomeClass::instanceMethod

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Method references — 3 main cases 37 instance::instanceMethod ! SomeClass::staticMethod ! SomeClass::instanceMethod Not covered by Groovy method closures yet!

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Groovy’s method closure 38 instance.&instanceMethod ! SomeClass.&staticMethod ! SomeClass.&instanceMethod

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Groovy’s method closure 38 instance.&instanceMethod ! SomeClass.&staticMethod ! SomeClass.&instanceMethod Choices: Adopt :: Deprecate .& Enhance .&

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Static methods in interfaces • You can put static utility methods in interfaces,   instead of in companion classes (like « Collections ») 39 public interface Stream { // ... static Stream empty() { return new Stream { ... } } }

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Default methods in interfaces • Define default behavior • possibly to enrich existing interfaces 40 public interface Stream { // ... default Builder add(T t) { ... } }

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Groovy Traits • Like interfaces, but with method bodies • similar to Java 8 interface default methods • Elegant way to compose behavior • multiple inheritance without the « diamond » problem • Traits can also be stateful • traits can have properties like normal classes • Compatible with static typing and static compilation • class methods from traits also visible from Java classes • Also possible to implement traits at runtime 41

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Simple trait 42 trait FlyingAbility { String fly() { "I'm flying!" } } ! class Bird implements FlyingAbility {} def b = new Bird() ! assert b.fly() == "I'm flying!"

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Trait with state 43 trait Named { String name } ! class Bird implements Named {} def b = new Bird(name: 'Colibri') ! assert b.name == 'Colibri'

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Multiple inheritance 44 trait KiteSurfer { String surf() { 'kite' } } ! trait WebSurfer { String surf() { 'web' } } ! class Person { String name } ! class Hipster extends Person implements KiteSurfer, WebSurfer {} ! def h = new Hipster() assert h.surf() == 'web'

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To know all about traits! 45 Rethinking API   design with traits by Cédric Champeau Tue 2:30pm / Trinity 3

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Annotations on types Repeating annotations

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Repeating annotations 47 @Schedule(dayOfMonth = "last") @Schedule(dayOfWeek = "Fri", hour = 23) public void doPeriodicCleanup() { ... }

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Repeating annotations 47 @Schedule(dayOfMonth = "last") @Schedule(dayOfWeek = "Fri", hour = 23) public void doPeriodicCleanup() { ... } @Schedule annotation repeated twice

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Repeating annotations 47 @Schedule(dayOfMonth = "last") @Schedule(dayOfWeek = "Fri", hour = 23) public void doPeriodicCleanup() { ... } @Repeatable(Schedules.class) public @interface Schedule { String dayOfMonth() default "first"; String dayOfWeek() default "Mon"; int hour() default 12; }

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Annotations on types • Everywhere you can put a type, you can put an annotation 48 @NonNull String name; ! email = (@Email String) input; ! List<@NonNull String> names; ! new @Interned MyObject(); ! void monitorTemperature() throws @Critical TemperatureException { ... } ! class UnmodifiableList implements @Readonly List<@Readonly T> {...}

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Groovy compile-time meta-annotations 49 @Service @Transactional class MyTransactionalService {}

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Groovy compile-time meta-annotations 49 @Service @Transactional class MyTransactionalService {} import groovy.transform.AnnotationCollector ! @Service @Transactional @AnnotationCollector public @interface TransactionalService {}

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Groovy compile-time meta-annotations 49 import groovy.transform.AnnotationCollector ! @Service @Transactional @AnnotationCollector public @interface TransactionalService {} ! @TransactionalService class MyTransactionalService {}

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Date and Time API

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Date / Time API 52 LocalDate.now(); today.with(TemporalAdjusters.lastDayOfMonth()).minusDays(2); ! LocalDate.of(2012, Month.MAY, 14); dateOfBirth.plusYears(1); ! LocalDate date = LocalDate.of(2000, Month.NOVEMBER, 20); LocalDate nextWed = date.with(TemporalAdjusters.next(DayOfWeek.WEDNESDAY));

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Groovy’s date / time handling 53 import static java.util.Calendar.* import groovy.time.* import org.codehaus.groovy.runtime.TimeCategory ! def cal = Calendar.instance cal.set(year: 2010, month: JULY, date: 9) ! assert FRIDAY == cal[DAY_OF_WEEK] ! use (TimeCategory) { 2.years + 3.months + 15.days + 23.minutes + 2.seconds ! 1.week - 1.day new Date() + 6.days ! 3.days.ago new Date() - 3 }

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Stream API

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map map map map map reduce reduce reduce reduce reduce

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map map map map map reduce reduce reduce reduce reduce Map / filter / reduce explained to your 6 year old

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map map map map map reduce reduce reduce reduce reduce

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Stream 56 persons.stream() .filter( p -> p.getAge() < 18 ) .map( p -> p.getName().toUpperCase() ) .sorted() .collect(Collectors.joining(", "));

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Groovy’s functional style with the GDK methods 57 persons .findAll { it.getAge() < 18 } .collect { it.name.toUpperCase() } .sort() .joining(", ")

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Groovy using streams too! 58 persons.stream() .filter { it.age < 18 } .map { it.name.toUpperCase() } .sorted() .collect(Collectors.joining(", "))

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Groovy using streams too! 58 persons.stream() .filter { it.age < 18 } .map { it.name.toUpperCase() } .sorted() .collect(Collectors.joining(", ")) Leveraging closure to « SAM » type coercion

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Groovy using streams too! 58 persons.stream() .filter { it.age < 18 } .map { it.name.toUpperCase() } .sorted() .collect(Collectors.joining(", "))

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Optional 59 Optional maybeName = Optional.of("Guillaume"); ! String result = maybeName.orElse("unknown") ! if (maybeName.ifPresent()) { System.out.println(maybeName.get()); } else { System.out.println("unknown"); }

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You know you can customize the truth in Groovy?

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You know you can customize the truth in Groovy? Just implement a custom asBoolean() method!

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The law of Groovy Truth 61

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The law of Groovy Truth 61 Everything that’s null, empty, zero-sized, equal to zero is false

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The law of Groovy Truth 61 Everything that’s null, empty, zero-sized, equal to zero is false Otherwise, it’s true!

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Groovy truth, null handling, Elvis with Optional 63 def maybeName = Optional.of("Guillaume") ! def result = maybeName ?: "unknown" ! if (maybeName) { println maybeName.get() } else { println "unknown" } ! maybeName?.toUpperCase()

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Nashorn

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Nashorn Speak German?

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Call JavaScript from Groovy with JSR-223 65 def manager = new ScriptEngineManager() def engine = manager.getEngineByName("nashorn") ! assert engine.eval("{} + []") == 0

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Call JavaScript from Groovy with JSR-223 65 def manager = new ScriptEngineManager() def engine = manager.getEngineByName("nashorn") ! assert engine.eval("{} + []") == 0 Sane JavaScript logic :-)

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GrooScript — http://grooscript.org/ 66 JS

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GrooScript — http://grooscript.org/ 66 JS Gradle & Grails plugins available Examples available with Ratpack, Node.JS…

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Turtles all the way down!

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Turtles all the way down! Full Groovy!

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Turtles all the way down! Full Groovy! Back to front

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Turtles all the way down! Full Groovy! Back to front Front to back

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Jackson Pollock

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JavaFx… ! ! …the new Swing

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GroovyFX 70 import javafx.scene.Scene import static groovyx.javafx.GroovyFX.start ! def chamber = ["5 Stelle": 108, "Italia.\nBene commune": 340, "Con Monti per l'Italia": 45, "Berlusconi": 124, "others": 4] ! start { stage(title: 'Italian chamber of Deputies', width: 1024, height: 700, visible: true) { Scene s = scene { tilePane { barChart(barGap: 10, categoryGap: 20, title: "Italy's election in February 2013") { series(name: 'Chamber (seats)', data: ['5 Stelle', 17.5, 'Monti', 7.8, 'Bene commune', 55, 'Berlusconi', 19.9]) series(name: 'Senate (seats)', data: ['5 Stelle', 17.4, 'Monti', 6.1, 'Bene commune', 39.1, 'Berlusconi', 37.1]) } pieChart(data: chamber, title: "Chamber of Deputies") } } s.stylesheets.add("Chart.css") } }

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Scripting 73 @Grab('net.sourceforge.htmlcleaner:htmlcleaner:2.4') import org.htmlcleaner.* ! def src = new File('html').toPath() def dst = new File('asciidoc').toPath() ! def cleaner = new HtmlCleaner() def props = cleaner.properties props.translateSpecialEntities = false def serializer = new SimpleHtmlSerializer(props) ! src.toFile().eachFileRecurse { f -> def relative = src.relativize(f.toPath()) def target = dst.resolve(relative) if (f.isDirectory()) { target.toFile().mkdir() } else if (f.name.endsWith('.html')) { def tmpHtml = File.createTempFile('clean', 'html') println "Converting $relative" def result = cleaner.clean(f) result.traverse({ tagNode, htmlNode -> tagNode?.attributes?.remove 'class' if ('td' == tagNode?.name || 'th'==tagNode?.name) { tagNode.name='td' String txt = tagNode.text tagNode.removeAllChildren() tagNode.insertChild(0, new ContentNode(txt)) } true } as TagNodeVisitor) serializer.writeToFile( result, tmpHtml.absolutePath, "utf-8" ) "pandoc -f html -t asciidoc -R -S --normalize -s $tmpHtml -o ${target}.adoc" .execute().waitFor() tmpHtml.delete() } } AsciiDoctor

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Ant scripting 74 @Grab('net.sourceforge.htmlcleaner:htmlcleaner:2.4') import org.htmlcleaner.* ! def src = new File('html').toPath() def dst = new File('asciidoc').toPath() ! def cleaner = new HtmlCleaner() def props = cleaner.properties props.translateSpecialEntities = false def serializer = new SimpleHtmlSerializer(props) ! src.toFile().eachFileRecurse { f -> def relative = src.relativize(f.toPath()) def target = dst.resolve(relative) if (f.isDirectory()) { target.toFile().mkdir() } else if (f.name.endsWith('.html')) { def tmpHtml = File.createTempFile('clean', 'html') println "Converting $relative" def result = cleaner.clean(f) result.traverse({ tagNode, htmlNode -> tagNode?.attributes?.remove 'class' if ('td' == tagNode?.name || 'th'==tagNode?.name) { tagNode.name='td'

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Ant scripting 75 def props = cleaner.properties props.translateSpecialEntities = false def serializer = new SimpleHtmlSerializer(props) ! src.toFile().eachFileRecurse { f -> def relative = src.relativize(f.toPath()) def target = dst.resolve(relative) if (f.isDirectory()) { target.toFile().mkdir() } else if (f.name.endsWith('.html')) { def tmpHtml = File.createTempFile('clean', 'html') println "Converting $relative" def result = cleaner.clean(f) result.traverse({ tagNode, htmlNode -> tagNode?.attributes?.remove 'class' if ('td' == tagNode?.name || 'th'==tagNode?.name) { tagNode.name='td' String txt = tagNode.text tagNode.removeAllChildren() tagNode.insertChild(0, new ContentNode(txt)) } true } as TagNodeVisitor) serializer.writeToFile( result, tmpHtml.absolutePath, "utf-8" )

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Ant scripting 76 def target = dst.resolve(relative) if (f.isDirectory()) { target.toFile().mkdir() } else if (f.name.endsWith('.html')) { def tmpHtml = File.createTempFile('clean', 'html') println "Converting $relative" def result = cleaner.clean(f) result.traverse({ tagNode, htmlNode -> tagNode?.attributes?.remove 'class' if ('td' == tagNode?.name || 'th'==tagNode?.name) { tagNode.name='td' String txt = tagNode.text tagNode.removeAllChildren() tagNode.insertChild(0, new ContentNode(txt)) } true } as TagNodeVisitor) serializer.writeToFile( result, tmpHtml.absolutePath, "utf-8" ) "pandoc -f html -t asciidoc -R -S --normalize -s $tmpHtml -o ${target}.adoc" .execute().waitFor() tmpHtml.delete() } }

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Android support • You can use Groovy to code Android apps! • use Groovy 2.4.0-beta-1+ • prefer @CompileStatic ! • Two great posts to get started: • http://melix.github.io/blog/2014/06/grooid.html • http://melix.github.io/blog/2014/06/grooid2.html 78

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New York Times — Getting Groovy with Android 79

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New York Times — Getting Groovy with Android 79 http://bit.ly/nyt-groovy

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What does NYT likes about Groovy on Android? • No Java 8, no lambda on Android… 80 Func0 func = new Func0() { @Override public String call() { return "my content"; } }; Async.start(func);

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What does NYT likes about Groovy on Android? • No Java 8, no lambda on Android… 81 ! ! ! ! ! ! Async.start { "my content" }

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What does NYT likes about Groovy on Android? • No Java 8, no lambda on Android… 81 ! ! ! ! ! ! Async.start { "my content" } Good bye annonymous inner classes!

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What does NYT likes about Groovy on Android? ! • Groovy code more concise and more readable ! • but just as type-safe as needed!  (with @TypeChecked) ! • but just as fast as needed!  (with @CompileStatic) 82

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Android support 83

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Android support 83

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Android support 83 Source code available: https://github.com/melix/gr8confagenda

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To know all about Android support 84 Groovy & Android,   a winning pair? by Cédric Champeau Thu 12:45pm / Trinity 3

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Grails — web framework 86 @Grab("com.h2database:h2:1.3.173") import grails.persistence.* ! @Entity @Resource(uri='/books') class Book { String title }

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Grails — web framework 86 @Grab("com.h2database:h2:1.3.173") import grails.persistence.* ! @Entity @Resource(uri='/books') class Book { String title } One class, one command, and you’ve got a full REST CRUD application!

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Ratpack — web framework 87 @GrabResolver("https://oss.jfrog.org/artifactory/repo") @Grab("org.ratpack-framework:ratpack-groovy:0.9.8") import static org.ratpackframework.groovy.RatpackScript.ratpack import static org.ratpackframework.groovy.Template.groovyTemplate ! ratpack { handlers { get { response.send "Welcome!" } ! get("date") { render groovyTemplate("date.html") } ! assets "public" } }

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@ArtifactProviderFor(GriffonModel) class ConsoleModel { String scriptSource @Observable Object scriptResult @Observable boolean enabled = true } Griffon — rich desktop applications 88

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@ArtifactProviderFor(GriffonModel) class ConsoleModel { String scriptSource @Observable Object scriptResult @Observable boolean enabled = true } Griffon — rich desktop applications 88 Model

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@ArtifactProviderFor(GriffonModel) class ConsoleModel { String scriptSource @Observable Object scriptResult @Observable boolean enabled = true } Griffon — rich desktop applications 88 Model @ArtifactProviderFor(GriffonController) class ConsoleController { def model ! @Inject Evaluator evaluator ! void executeScript() { model.enabled = false def result try { result = evaluator.evaluate(model.scriptSource) } finally { model.enabled = true model.scriptResult = result } } } Controller application(title: application.configuration['application.title'], pack: true, locationByPlatform: true, id: 'mainWindow', iconImage: imageIcon('/griffon-icon-48x48.png').image, iconImages: [imageIcon('/griffon-icon-48x48.png').image, imageIcon('/griffon-icon-32x32.png').image, imageIcon('/griffon-icon-16x16.png').image]) { panel(border: emptyBorder(6)) { borderLayout() scrollPane(constraints: CENTER) { textArea(text: bind(target: model, 'scriptSource'), enabled: bind { model.enabled }, columns: 40, rows: 10) } ! hbox(constraints: SOUTH) { button(executeScriptAction) hstrut(5) label('Result:') hstrut(5) textField(editable: false, text: bind { model.scriptResult }) } } } View

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Spock — unit testing & specification 89 @Grab('org.spockframework:spock-core:0.7-groovy-2.0') import spock.lang.* ! class MathSpec extends Specification { def "maximum of two numbers"() { expect: Math.max(a, b) == c ! where: a | b || c 1 | 3 || 3 7 | 4 || 7 0 | 0 || 0 } }

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Geb — browser automation 90 import geb.Browser ! Browser.drive { go "http://myapp.com/login" ! assert $("h1").text() == "Please Login" ! $("form.login").with { username = "admin" password = "password" login().click() } ! assert $("h1").text() ==   "Admin Section" }

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Gradle — build automation 91 apply plugin: 'java' apply plugin: 'eclipse' ! sourceCompatibility = 1.5 version = '1.0' jar { manifest { attributes 'Implementation-Title': 'Gradle Quickstart' } } ! repositories { mavenCentral() } ! dependencies { compile ‘commons-collections:commons-collections:3.2’ testCompile 'junit:junit:4.+' } ! uploadArchives { repositories { flatDir { dirs 'repos' } } }

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GPars — concurrency / parallelism / async / … 92 import static groovyx.gpars.actor.Actors.actor ! def decryptor = actor { loop { react { message -> if (message instanceof String) reply message.reverse() else stop() } } } ! def console = actor { decryptor.send 'lellarap si yvoorG' react { println 'Decrypted message: ${it}' decryptor.send false } } ! [decryptor, console]*.join()

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Groovy modules • Ant scripting • JMX • JSON • Servlet • Swing • SQL • Templating • Testing • XML 94

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Groovy modules • Ant scripting • JMX • JSON • Servlet • Swing • SQL • Templating • Testing • XML 95

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Ant + XML 96 def writer = new StringWriter() def mkp = new MarkupBuilder(writer) ! mkp.html { head { title 'Build notification' } body { p 'Your build was successful' } } ! new AntBuilder().mail(mailhost: 'localhost', messagemimetype: 'text/html', subject: 'Build successful') { ! from address: '[email protected]' to address: '[email protected]' message writer attchments { fileset(dir: 'dist') { include name: '**/logs*.txt' } } }

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JSON support — creating JSON 97 import groovy.json.* ! def json = new JsonBuilder() json.person { name 'Guillaume' age 37 daughters 'Marion', 'Erine' address { street '1 Main Street' zip 75001 city 'Paris' } } { "person": { "name": "Guillaume", "age": 37, "daughters": [ "Marion", "Erine" ], "address": { "street": "1 Main Street", "zip": 75001, "city": "Paris" } } }

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JSON support — parsing JSON 98 import groovy.json.* ! def url =   "https://api.github.com/repos/groovy/groovy-core/commits" ! def commits = new JsonSlurper().parseText(url.toURL().text) ! assert commits[0].commit.author.name == 'Cedric Champeau'

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Template module — new markup template engine • Based on the principles of Groovy’s « builders » • and particularly the MarkupBuilder class  for generating arbitrary XML / HTML payloads ! • Compiled statically for fast template rendering ! • Internationalization aware • provide the desired Locale in the configuration object • usual suffix notation template_fr_FR.tpl ! • Custom base template class • ability to provide reusable methods across your templates 99

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Markup template engine — the idea 100 cars { cars.each { car(make: it.make, name: it.name) } }

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Markup template engine — the idea 100 cars { cars.each { car(make: it.make, name: it.name) } } Your template

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Markup template engine — the idea 100 cars { cars.each { car(make: it.make, name: it.name) } } model = [cars: [ new Car(make: 'Peugeot', name: '508'), new Car(make: 'Toyota', name: 'Prius’) ]]

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Markup template engine — the idea 100 cars { cars.each { car(make: it.make, name: it.name) } } model = [cars: [ new Car(make: 'Peugeot', name: '508'), new Car(make: 'Toyota', name: 'Prius’) ]] Feed a model into your template

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Markup template engine — the idea 100 cars { cars.each { car(make: it.make, name: it.name) } } model = [cars: [ new Car(make: 'Peugeot', name: '508'), new Car(make: 'Toyota', name: 'Prius’) ]]

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Markup template engine — the idea 100 cars { cars.each { car(make: it.make, name: it.name) } } model = [cars: [ new Car(make: 'Peugeot', name: '508'), new Car(make: 'Toyota', name: 'Prius’) ]]

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Markup template engine — in action 101 import groovy.text.markup.* ! def config = new TemplateConfiguration() def engine = new MarkupTemplateEngine(config) def tmpl = engine.createTemplate(''' p("Hello ${model.name}") ''') def model = [name: 'World'] System.out << tmpl.make(model)

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Back to our original question… 103 Do we still need Groovy now that we have Java 8?

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Longer answer: Yes, because… • You can benefit from Java 8 in Groovy 105 Synergy  the whole is   greater than the sum of the parts

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Longer answer: Yes, because… • Groovy goes beyond what Java 8 offers 106 Beyond  Groovy always tries to add something to the table

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Questions still open: Syntax support for… • lambdas • not necessarily,  (confusing / duplication) ! • method references • enhance method closures • or replace them with method references ! • interface default methods • yes: traits methods aren’t default methods • repeated annotations • yes: not urgent • but less boilerplate is good ! • annotations on type • yes: opens up new possibilities for targets of local AST transformation ! • interface static methods • yes: for Java compatibility 107

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Further possible API enhancements • Make Optional Groovy-friendly • with regards to Groovy Truth • accessing the wrapped value ! • More Groovy methods for… • NIO • Streams • Date / time ! • Operator overloading for Date / time • for arithmetics on instants and durations 108

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More Java 8 coverage 109 Java 8 language capabilities by V. Subramaniam Thu 10:30pm / D.Ball.G

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More Java 8 coverage 110 How to get Groovy with Java 8 by Peter Ledbrook Thu 10:30pm / Trinity 3

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Java 8 in Action ! • By Urma, Fusco and Mycrof • Plublished by Manning • http://www.manning.com/urma/ 111

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Image credits • Question mark • http://www.mynamesnotmommy.com/wp-content/uploads/2013/05/question-mark.png • Get out! • http://static.comicvine.com/uploads/original/11/117995/3772037-0075368930-27616.jpg • Yes • http://soloprpro.com/wp-content/uploads/2013/08/yes.jpg • Synergy • http://www.wildblueberries.com/wp-content/uploads/blogger/_YhH8fDK5-kU/S_5kYWwgAbI/AAAAAAAAAKU/JQ_-ISfT9KY/ s1600/teamwork.jpg • Buzz Lightyear • http://www.disneypictures.net/data/media/202/Buzz_Lightyear_hd.jpg • Start wars spaceship • http://swc.fs2downloads.com/media/screenshots/Support_Trans/Shuttle/lambda003.jpg • Lambda character • http://lambda.ninjackaton.ninja-squad.com/images/lambda.png • Man clock • http://3.bp.blogspot.com/-7hLQ9tnmA84/TuTIoLRLMTI/AAAAAAAABWM/g7ahyLCRjJQ/s1600/Harold+Lloyd+Safety+Last.jpg • Stream • http://wallpaperswide.com/forest_stream-wallpapers.html • Nashorn (rhino) • http://2010sdafrika.files.wordpress.com/2012/07/hi_257587-nashorn-c-naturepl-com-mark-carwardine-wwf-canon.jpg 114

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Image credits • Brain • http://www.semel.ucla.edu/sites/all/files/users/user-412/dreamstime_xxl_17754591%20(2).jpg • Many thanks • http://www.trys.ie/wp-content/uploads/2013/06/many-thanks.jpg • Swing • http://makemesomethingspecial.co.uk/wp-content/uploads/2012/10/Solid-Oak-Handmade-Spliced-Swing-With-Personalised- Engraving-10867.jpg • Disclaimer • http://3.bp.blogspot.com/-RGnBpjXTCQA/Tj2h_JsLigI/AAAAAAAABbg/AB5ZZYzuE5w/s1600/disclaimer.jpg • Hammer / justice / truth • http://www.bombayrealty.in/images/disclaimer.jpg • Law • http://www.permanentmakeupbymv.com/wp-content/uploads/2014/07/law-2.jpg • Glasses / readable • http://a.fastcompany.net/multisite_files/coexist/imagecache/1280/poster/2013/02/1681393-poster-1280-responsive-eye-chart.jpg • We need you • http://www.bostonbreakerssoccer.com/imgs/ABOUT/volopps/we%20need%20you.JPG 115

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Image credits • Jackson Pollock • http://www.ibiblio.org/wm/paint/auth/pollock/pollock.number-8.jpg • Turtles • http://33.media.tumblr.com/77095e3a37acb2272133c405b1f7ba54/tumblr_myfydjNgXJ1s20kxvo1_1280.jpg • Annotations • http://3.bp.blogspot.com/-f94n9BHko_s/T35ELs7nYvI/AAAAAAAAAKg/qe06LRPH9U4/s1600/IMG_1721.JPG • Builders • http://detroittraining.com/wp-content/uploads/Construction-Women2.jpg • Sandwich ingredients • http://www.fromages-de-terroirs.com/IMG/MEULE_DETOUREE_72_DPI_-2.jpg • http://eboutique-hebergement.orange-business.com/WebRoot/Orange/Shops/Madeinalsace/4B02/6320/943E/DB4F/DDBF/ 0A0A/33E8/4BC8/iStock_000008775559XSmall.jpg • http://www.cmonprimeur.fr/images/25834-vegetable-pictures%5B1%5D.jpg • http://1.bp.blogspot.com/-27UoqYeYtY4/T4PAr4zGSnI/AAAAAAAAA3s/lleE-NOh0LE/s1600/IMG_1528.JPG • http://www.growingpatch.com/wp-content/uploads/2014/05/tomato-9.jpg • http://vitaminsandhealthsupplements.com/wp-content/uploads/2013/08/fresh-sliced-tomato.jpg • http://2.bp.blogspot.com/-3pPmRhBHv9s/T3D-EtLlN1I/AAAAAAAAAgg/Y5oTM84nGb8/s1600/cochon+2.jpg • http://www.salamarket.fr/wp-content/uploads/steak-hach%C3%A9.jpg • http://www.quinzanisbakery.com/images/bread-vienna.jpg • http://www.saucissonvaudois.qc.ca/images/produits/Jambon_blanc.jpg • http://www.audion.com/system/public/categories/125/images/bread-sandwich.jpg 116