Java8 Neue Sprachfeatures - Lambda/Streams/default Methods/FunctionalInterfaces

λ Lambda-Ausdrücke Method::References Method default methods ≈≈ Streams @ FunctionalInterfaces

t Feb. 2002 Java 1.4 • • • • • • Assert ------------Regex NIO Logging JAXP JAAS/JSSE Sep. 2004 Java 1.5 • • • • • ? Generics -------------------------Varargs Compiler API Foreach Loop Scripting (JSR223) JAXB Improvements Static Imports JAX-WS Autoboxing JVM (Performance,...) -------------------Java.util.concurrent • • • • • • • • • • • Mär. 2014 Java 1.8 Jul. 2011 Java 1.7 Dez. 2006 Java 1.6 • • Switch (Strings) ARM (try-w-R) Diamond operator Multi-Exceptions Num-Literals -----------------------NIO2 invokeDynamic • • • • • Lambdas Method Refs. Default Meth. Functional Ifc Stream

C# 3.0 C# 2.0 Generics t Extension Methods, Lambdas Nov. 2007 Feb. 2002 Java 1.4 • • • • • • Assert ------------Regex NIO Logging JAXP JAAS/JSSE Sep. 2004 Java 1.5 • • • • • ? Generics -------------------------Varargs Compiler API Foreach Loop Scripting (JSR223) JAXB Improvements Static Imports JAX-WS Autoboxing JVM (Performance,...) -------------------Java.util.concurrent • • • • • • • • • • • Mär. 2014 Java 1.8 Jul. 2011 Java 1.7 Dez. 2006 Java 1.6 • • Switch (Strings) ARM (try-w-R) Diamond operator Multi-Exceptions Num-Literals -----------------------NIO2 invokeDynamic • • • • • Lambdas Method Refs. Default Meth. Functional Ifc Stream

(int a, int b) → { return a * b; } (int a, int b) → a* b (a, b) → a* b x→ x*x

interface Callback { public int doit(int x); };

java.lang.Runnable void run() java.util.concurrent.Callable<V> V call() java.awt.event.ActionListener void actionPerformed(ActionEvent e) java.beans.PropertyChangeListener void propertyChange(PropertyChangeEvent evt) java.io.FileFilter boolean accept(File pathname) java.util.Comparator<T> int compare(T o1, T o2) javax.naming.spi.ObjectFactory Object getObjectInstance(.....)

someThing.addCallback( new Callback() { public int doit(int x) { return x *x; } });

someThing.addCallback( (int x) → { return x *x; } );

someThing.addCallback( (int x) → x *x );

someThing.addCallback( x → x *x );

(int a, int b) → { return a * b; } (int a, int b) → a* b; (a, b) → a* b; x → x * x;

some.method(Integer::parseInt); Statische Methode

someList.forEach(MyClass::instMeth); someList.forEach( (MyClass e) → e.instMeth() ); Ungebundene Instanz-Methode

some.method(System.out::println); some.method(instance::instmethod); Gebundene Instanz-Methode

some.method(MyClass::new); some.method((x) -> new MyClass(x)); Konstruktor

List<Point> points = …. Iterator<Point> it = points.iterator(); while(it.hasNext()) { Point p = it.next(); …. …. }

List<Point> points = …. Stream<Point> it = points.stream(); while(it.hasNext()) { Point p = it.next(); …. …. }

List<Point> points = …. X Stream<Point> it = points.stream(); X while(it.hasNext()) { Point p = it.next(); …. …. }

List<Point> points = …. points.stream() .map(p->p.x) .filter(v-> v > 0) .distinct() .forEach(out::println) ;

Point Point Point Point Point Point Point Point map p → p.x int Point Point Point int Point Point Point filter int int Point int v → v>0 distinct int Point foreach out::println

List<Point> points = …. points.parallelStream() .map(p->p.x) .filter(v-> v > 0) .distinct() .forEach(out::println) ;

interface MyInterface { public int doit(int x); static int other(int x){ ...some Implementation } };

interface MyInterface { public int doit(int x); default int other(int x){ ...Implementation using this } };

@FunctionalInterface interface MyInterface { public int doit(int x); };

package java.util.function @FunctionalInterface interface Function<T, R> { R apply(T t); };

package java.util.function @FunctionalInterface interface BiFunction<T, U, R> { R apply(T t, U u); };

package java.util.function @FunctionalInterface interface Consumer<T> { void accept(T t); };

package java.util.function @FunctionalInterface interface Supplier<T> { T get(); };

package java.util.function @FunctionalInterface interface Predicate<T> { boolean test(T t); };

Consumer<Integer> outp = (i) -> System.out.println(i); Function<String, Integer> fun = (s) -> s.length(); Supplier<String> value = () -> "Hello"; outp.accept(fun.apply(value.get()));

Consumer<Integer> outp = (i) -> System.out.println(i); Function<String, Integer> fun = (s) -> s.length(); Supplier<String> value = () -> "Hello"; outp ( fun ( value() ) );

Weiterführendes: State of the Lambda – Brian Goetz erklärt die Java 8 Features. http://cr.openjdk.java.net/~briangoetz/lambda/lambda-state-final.html Lambda – A peek under the hood http://www.youtube.com/watch?v=C_QbkGU_lqY&noredirect=1 Brian Goetz erklärt, wie Lambdas implementiert sind. Lambda/Streams Tutorial auf AngelikaLanger.com http://www.angelikalanger.com/Lambdas/Lambdas.html Lambda-FAQ von Maurice Naftalin http://www.lambdafaq.org Artikel von Angelika Langer und Klaus Kreft in Java Magazin 10.2013 und 11.2013 Java8 complete feature set http://openjdk.java.net/projects/jdk8/features

Weiterführendes: Netbeans 7.4 https://netbeans.org/community/releases/74/ Java 8 Early Access https://jdk8.java.net/download.html Online Compiler – Try Java 8 http://www.tryjava8.com Java 8 Lambdas in Action (MEAP) Raoul-Gabriel Urma, Mario Fusco, and Alan Mycroft http://www.manning.com

forEach( (Aufmerksamkeit) → Vielen Dank )

Dirk Detering ©2013 Version 0.7 Dieses Projekt ist lizensiert als Inhalt der Creative Commons Namensnennung - Nicht-kommerziell Weitergabe unter gleichen Bedingungen 3.0 Deutschland-Lizenz. Um eine Kopie der Lizenz zu sehen, besuchen Sie http://creativecommons.org/licenses/by-nc-sa/3.0/de/. Java is a registered trademark of Oracle and/or its affiliates.

Java8 Neue Sprachfeatures - Lambda/Streams/default Methods/FunctionalInterfaces

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