(deutsch) Kurze Einführung in Java8 - neue Sprachfeatures rund um Lambda

1. Neue Sprachfeatures

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

4. 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

5. 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

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

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

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

9. 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(.....)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

34. 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

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

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

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

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

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

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

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

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

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

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

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

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

47. 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()));

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

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

50. 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

51. 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

52. forEach( (Aufmerksamkeit) → Vielen Dank )

54. Dirk Detering ©2013
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