The document summarizes an upcoming Java user group meeting to discuss Java 7 features. It will cover new language features in Java 7 like binary literals, string switches, and try-with-resources statements. It will also cover parallel programming enhancements like Fork/Join and NIO.2. The meeting will include hands-on demos of Java 7 features and a discussion of upcoming Java 8 features. Refreshments will be provided by meeting sponsor Ovialis.

2.  Sébastien Prunier
› Architecte JEE chez Ovialis
› Adepte des JUGs
› Certifié Bonita OS
 @sebprunier
 gplus.to/sebprunier
 Java User Blog !
› sebprunier.wordpress.com

3.  Relations avec des partenaires
technologiques

4.  19h – 21h (max)
 Pot offert par Ovialis
http://www.xebia.fr/xebia-essentials

6.  Ce soir nous allons donc parler de Java !

7.  Refactoring de code
Source : http://www.energizedwork.com

8.  Sortie officielle de Java SE 7

9.  JSR 334 – Project Coin
› Evolutions du langage
 JSR 292 – InvokeDynamic
› Support pour les langage dynamiques
 JSR 166 – Fork / Join
› Programmation parallèle
 JSR 203 – NIO.2
› Nouvelles APIs
 Et d’autres petites nouveautés sympa !

10.  Binary Literals
 Underscores in Numeric Literals
 String in switch Statements
 Multiple Catch and More Precise Rethrow
 Type Inference for Generics Instanciation
 Try-with-resource Statement
 Simplified Varargs Method Invocation

11.  Avant
// 213
int binarynumber = Integer.parseInt("11010101", 2);
 Après
// 213
int binarynumber = 0b11010101;

12.  Avant
int bignumber = 45321589;
 Après
int bignumber = 45_321_589;
// 213
int binarynumber = 0b1101_0101;

13.  Qui n’a pas essayé cela avant Java 7 ?
String command = args[0];
switch (command) {
case "start":
MyApplication.start();
break;
case "stop":
MyApplication.stop();
break;
default:
// Manage error
break;
}

14.  Objectif : factoriser !
try {
// Database access stuff ...
}
catch (ClassNotFoundException | SQLException e) {
System.err.println("Error during database
access : " + e.getMessage());
}
catch (Exception e) {
System.err.println("Unexpected error !"
+ "Please contact the technical support");
}

15.  Avant
private void manageData()
throws SQLException, IOException {
// Database access, File access ...
}
public void myAction() throws Exception {
try {
manageData();
} catch (Exception e) {
// your stuff here !
throw e;
}
}

16.  Après
private void manageData()
throws SQLException, IOException {
// Database access, File access ...
}
public void myAction() throws
SQLException, IOException {
try {
manageData();
} catch (Exception e) {
// your stuff here !
throw e;
}
}

17.  Avant
List<String> list = new ArrayList<String>();
Map<String, Integer> map = new HashMap<String, Integer>();
Map<String, List<BigDecimal>> map2 = new HashMap<String, Lis

18.  Après
List<String> list = new ArrayList<>();
Map<String, Integer> map = new HashMap<>();
Map<String, List<BigDecimal>> map2 = new HashMap<>();

19.  ZE nouveauté !
 Un réel intérêt : éviter des bugs bêtes
try (BufferedReader reader = new BufferedReader(…)) {
String line = reader.readLine();
while (line != null) {
System.out.println(line);
line = reader.readLine();
}
} catch (IOException e) {
System.err.println("Erreur : " + e.getMessage());
}
finally{…} close()

20.  java.lang.AutoCloseable
public class MyResource implements AutoCloseable {
...
@Override
public void close() throws Exception {
// Your stuff here !
}
}

21.  @SafeVarargs
@SafeVarargs
public static <T> void addToList(List<T> listArg,
T... elements) {
for (T x : elements) {
listArg.add(x);
}
}
Type safety: Potential heap pollution via varargs parameter elements

22.  java.util.Objects
 9 méthodes utilitaires sur les « Object »
 Un vrai + pour du code plus simple, plus
lisible
 Deux exemple dans la démo :
› Objects.toString()
› Objects.hash()

23. > javadoc -stylesheetfile MyStylesheet.css

24.  Exemple de la copie de fichiers
› java.nio.file.*
FileSystem fs = FileSystems.getDefault();
Path src = fs.getPath("/home", "source.txt");
Path tgt = fs.getPath("/backup", "target.txt");
Files.copy(src, tgt, StandardCopyOption.REPLACE_EXISTING);

25.  Un peu de lecture si vous le souhaitez …
http://groups.google.com/group/lescastcodeurs/msg/90ddf025c52a9412

26.  Tirer parti des processeurs multiples
 API de programmation parallèle
 Voir aussi
› Map / Reduce
› Hadoop
› GridGain

27.  Approche très simple
if (my portion of the work is small enough)
do the work directly
else
split my work into two pieces
invoke the two pieces and wait for the results
 Démo !
http://download.oracle.com/javase/tutorial/essential/concurrency/forkjoin.html

28.  Collection Literals
› Initialement dans Coin
List<Integer> piDigits = [3, 1, 4, 1, 6, 5, 3, 5, 9];
Set<Integer> primes = { 2, 7, 31, 127, 8191, 131071};
Map<Integer, String> platonicSolids =
{ 4 : "tetrahedron", 6 : "cube", 8 : "octahedron", 12 :
"dodecahedron", 20 : "icosahedron" };
http://mail.openjdk.java.net/pipermail/coin-dev/2009-March/001193.html

29.  JSR 335 – Lamba Expressions
› Closures
› Fonctions anonymes
x -> x + 1
(x) -> x + 1
(int x) -> x + 1
(int x, int y) -> x + y
(x, y) -> x + y
http://mail.openjdk.java.net/pipermail/lambda-dev/2011-September/003936.html

30.  Modularité : Projet JIGSAW
module-info.java
module com.greetings @ 0.1 {
requires jdk.base; // default to the highest available
version requires org.astro @ 1.2;
class com.greetings.Hello;
}
http://openjdk.java.net/projects/jigsaw/

31.  Java 7 : Hands-On !
› Démo sur GitHub
› https://github.com/sebprunier/nantesjug-java7
 Java 8 : Watch !
› Sortie prévue été 2013
 Java 9 …

32.  Questions / Réponses