La sortie de Java 8 est une véritable révolution dont l’enjeu dépasse de loin la simple évolution d’un langage et de ses APIs. Rdv sur notre chaîne Youtube pour revoir la conférence : Après une version 7 peu convaincante, la version 8 replace Java au premier rang des langages objets actuels. En parfaite adéquation avec les besoins des projets et les possibilités offertes par les environnements matériels actuels, cette nouvelle version apporte une modernisation du langage et de ses API, un suivi des performances des processeurs et des améliorations de la JVM. Quels sont les nouveaux concepts introduits par Java 8 ? En quoi les expressions lambdas et l’API Stream représentent une avancée majeure de la plateforme ? Quelle stratégie adopter pour migrer vers Java 8 en toute sécurité et en diminuant au maximum sa dette technique ?

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17. source : http://www.oracle.com/technetwork/java/eol-135779.html

18. source : http://blog.soat.fr/?p=29705

24. List<String> datas = Arrays.asList("one", "two", "three");
datas.forEach(new Consumer<String>() {
@Override
public void accept(String elt) {
System.out.println(elt);
}
});

25. List<String> datas = Arrays.asList("one", "two", "three");
datas.forEach(new Consumer<String>() {
@Override
public void accept(String elt) {
System.out.println(elt);
}
});

26. List<String> datas = Arrays.asList("one", "two", "three");
datas.forEach(new Consumer<String>() {
@Override
public void accept(String elt) {
System.out.println(elt);
}
});

27. List<String> datas = Arrays.asList("one", "two", "three");
datas.forEach(elt -> System.out.println(elt));

30. Resource resource = null;
try {
resource = new Resource();
resource.doJob();
} catch (Exception ex) {
ex.printStackTrace();
} finally {
if (resource != null) {
try {
resource.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}

31. try(Resource resource = new Resource()) {
resource.doJob();
} catch (Exception ex) {
ex.printStackTrace();
}

32. try(Resource resource = new Resource()) {
resource.doJob();
} catch (Exception ex) {
ex.printStackTrace();
}

33. public static void doWithResource(Consumer<Resource> lambda)
{
Resource resource = null;
try {
resource = new Resource();
lambda.accept(resource);
} finally {
if(resource != null) {
try {
resource.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}

34. public static void doWithResource(Consumer<Resource> lambda)
{
Resource resource = null;
try {
resource = new Resource();
lambda.accept(resource);
} finally {
if(resource != null) {
try {
resource.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}

35. public static void doWithResource(Consumer<Resource> lambda)
{
Resource resource = null;
try {
resource = new Resource();
lambda.accept(resource);
} finally {
if(resource != null) {
try {
resource.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}

36. doWithResource(resource -> resource.doJob());

38. Map<String, String> map = new HashMap<>();
String key = "KEY";
if(!map.containsKey(key)) {
map.put(key, key.concat("_COMPUTED"));
}
String result = map.get(key);

39. Map<String, String> map = new HashMap<>();
String key = "KEY";
if(!map.containsKey(key)) {
map.put(key, key.concat("_COMPUTED"));
}
String result = map.get(key);

40. Map<String, String> map = new HashMap<>();
String key = "KEY";
String result = map.computeIfAbsent(key,
k -> key + "_COMPUTED");

41. Map<String, String> map = new HashMap<>();
String key = "KEY";
String result = map.computeIfAbsent(key,
k -> key + "_COMPUTED");

43. List<String> red = colors.stream()
.filter(c -> "RED".equals(c))
.collect(Collectors.toList());

48. Registry registry = new Registry();
List<User> users = new ArrayList<>();
for (Group group : registry.getGroups()) {
for (User user : group.getUsers()) {
if(user.getAge() >= 18) {
users.add(user);
}
}
}

49. Registry registry = new Registry();
List<User> users = new ArrayList<>();
for (Group group : registry.getGroups()) {
for (User user : group.getUsers()) {
if(user.getAge() >= 18) {
users.add(user);
}
}
}

50. Registry registry = new Registry();
List<User> users = new ArrayList<>();
for (Group group : registry.getGroups()) {
for (User user : group.getUsers()) {
if(user.getAge() >= 18) {
users.add(user);
}
}
}

51. Registry registry = new Registry();
List<User> users = new ArrayList<>();
for (Group group : registry.getGroups()) {
for (User user : group.getUsers()) {
if(user.getAge() >= 18) {
users.add(user);
}
}
}

52. Registry registry = new Registry();
List<User> users = registry.getGroups()
.stream()
.flatMap(grp -> grp.getUsers().stream())
.filter(u -> u.getAge() >= 18)
.collect(Collectors.toList());

53. Registry registry = new Registry();
List<User> users = registry.getGroups()
.stream()
.flatMap(grp -> grp.getUsers().stream())
.filter(u -> u.getAge() >= 18)
.collect(Collectors.toList());

54. Registry registry = new Registry();
List<User> users = registry.getGroups()
.stream()
.flatMap(grp -> grp.getUsers().stream())
.filter(u -> u.getAge() >= 18)
.collect(Collectors.toList());

55. Registry registry = new Registry();
List<User> users = registry.getGroups()
.stream()
.flatMap(grp -> grp.getUsers().stream())
.filter(u -> u.getAge() >= 18)
.collect(Collectors.toList());

56. Registry registry = new Registry();
List<User> users = registry.getGroups()
.stream()
.flatMap(grp -> grp.getUsers().stream())
.filter(u -> u.getAge() >= 18)
.collect(Collectors.toList());

58. Registry registry = new Registry();
List<User> users = registry.getGroups()
.stream()
.flatMap(grp -> grp.getUsers().stream())
.filter(u -> u.getAge() >= 18)
.collect(Collectors.toList());

59. Registry registry = new Registry();
List<User> users = registry.getGroups()
.stream()
.flatMap(grp -> grp.getUsers().stream())
.filter(u -> u.getAge() >= 18)
.collect(Collectors.toList());

60. public List<User> filterUsers(Registry registry,
Predicate<User> filter) {
return registry.getGroups()
.stream()
.flatMap(grp -> grp.getUsers().stream())
.filter(filter)
.collect(Collectors.toList());
}

61. public List<User> filterUsers(Registry registry,
Predicate<User> filter) {
return registry.getGroups()
.stream()
.flatMap(grp -> grp.getUsers().stream())
.filter(filter)
.collect(Collectors.toList());
}

62. public List<User> filterUsers(Registry registry,
Predicate<User> filter) {
return registry.getGroups()
.stream()
.flatMap(grp -> grp.getUsers().stream())
.filter(filter)
.collect(Collectors.toList());
}

63. public List<User> filterUsers(Registry registry,
Predicate<User> filter) {
return registry.getGroups()
.stream()
.flatMap(grp -> grp.getUsers().stream())
.filter(filter)
.collect(Collectors.toList());
}

64. Registry registry = new Registry();
filterUsers(registry, u -> u.getAge() >= 18);
filterUsers(registry, u -> u.getName().startsWith("John"));

65. Registry registry = new Registry();
List<User> users = registry.getGroups()
.stream()
.flatMap(grp -> grp.getUsers().stream())
.filter(u -> u.getAge() >= 18)
.collect(Collectors.toList());

66. Registry registry = new Registry();
List<User> users = registry.getGroups()
.stream()
.flatMap(grp -> {
return grp.getUsers()
.stream()
.filter(u -> {
return u.getAge() >= 18;
});
})
.collect(Collectors.toList());

68. Registry registry = new Registry();
List<User> users = registry.getGroups()
.stream()
.flatMap(grp -> grp.getUsers().stream())
.filter(u -> u.getAge() >= 18)
.collect(Collectors.toList());

69. Registry registry = new Registry();
List<User> users = registry.getGroups()
.stream()
.flatMap(grp -> grp.getUsers().stream())
.filter(u -> u.getAge() >= 18)
.collect(Collectors.toList());

70. Registry registry = new Registry();
List<User> users = registry.getGroups()
.parallel()
.flatMap(grp -> grp.getUsers().stream())
.filter(u -> u.getAge() >= 18)
.collect(Collectors.toList());

74. User remoteUser = null;
// NullPointerException
System.out.println("User name : " + remoteUser.getName());

75. Optional<User> user = Optional.ofNullable(remoteUser);
user.ifPresent(u -> System.out.println("User name : " + u.getName()));

76. Optional<User> user = Optional.ofNullable(remoteUser);
user.ifPresent(u -> System.out.println("User name : " + u.getName()));

77. Optional<User> user = Optional.ofNullable(remoteUser);
user.ifPresent(u -> System.out.println("User name : " + u.getName()));

78. user.flatMap(u -> Optional.ofNullable(u.getName()))
.ifPresent(name -> System.out.println("User name :" + name));

79. user.flatMap(u -> Optional.ofNullable(u.getName()))
.ifPresent(name -> System.out.println("User name :" + name));

80. user.flatMap(u -> Optional.ofNullable(u.getName()))
.ifPresent(name -> System.out.println("User name :" + name));

81. if(user != null) {
if(user.getName() != null) {
System.out.println("User name :" + user.getName());
}
}

82. Optional<String> birthdate = remoteUser.getBirthdate();

89. LocalDate newDate = LocalDate.now().plusDays(3)
.plusMonths(2);
LocalDateTime newDateTime = LocalDateTime.now()
.plusMinutes(3)
.plusSeconds(6)
.plusDays(2);

90. LocalDate newDate = LocalDate.now().plusDays(3)
.plusMonths(2);
LocalDateTime newDateTime = LocalDateTime.now()
.plusMinutes(3)
.plusSeconds(6)
.plusDays(2);

91. LocalDate newDate = LocalDate.now().plusDays(3)
.plusMonths(2);
LocalDateTime newDateTime = LocalDateTime.now()
.plusMinutes(3)
.plusSeconds(6)
.plusDays(2);

99. Source : http://www.oracle.com/technetwork/java/javase/8-compatibility-guide-2156366.html

100. new BigDecimal("0.00").stripTrailingZeros().equals(BigDecimal.ZERO))

101. new BigDecimal("0.00").stripTrailingZeros().equals(BigDecimal.ZERO))

102. new BigDecimal("0.00").stripTrailingZeros().equals(BigDecimal.ZERO))

105. …