2012/05/26 JavaQne(じゃばきゅん) Fukuoka 2012 発表資料 「Java SE 7、そしてJava SE 8」

1. Java SE 7,
そして Java SE 8
Java in the Box
櫻庭 祐一

2. Agenda History
Java SE 7
Java SE 8
Conclusion

3. History

4. 04 05 06 07 08 09 10
OpenJDK SE6u10 Sun 買収 Plan A
6と7は J2SE5.0 Java SE6
General リリース Plan B
一緒に計画 リリース リリース
JavaFX 発表
G.Hamiltion M.Reinhold M.Reinhold
friend JSR294Superpackage Jigsaw
Modularity
JAR の拡張 NewPackaging JSR277JAM JSR277Module
Closure BGGA Closure Closure Lambda
Parallel
N.Gafter JSR166y
NIO2 NIO2 NIO2 NIO2
JSR296SAF JSR296SAF SmallChanges Coin
EoD JSR295BeansBinding JSR295BeansBinding
JSR303BeanValidation
JSR308Annotation JSR308Annotation
Misc JSR121 NewBytecode JSR292 JSR292 JSR292 JSR292
Isolation XML リテラル JSR310DateTime JSR310DateTime
BeanShell BeanShell JMX2.0

5. 7
Project Coin
plan A NIO.2
InvokeDynamic
Fork/Join Framework
Project Lambda
Mid 2012
Project Jigsaw
7
Project Coin
NIO.2
plan B
8
InvokeDynamic
Fork/Join Framework
Mid 2011
Project Lambda
Project Jigsaw
Late 2012

6. 7
Project Coin
plan A NIO.2
InvokeDynamic
Fork/Join Framework
Project Lambda
Mid 2012
Project Jigsaw
7
Project Coin
NIO.2
plan B
8
InvokeDynamic
Fork/Join Framework
Mid 2011
Project Lambda
Project Jigsaw
Late 2012
Mid 2013

7. Project Coin
switch 文で文字列
2 進数と区切り文字
例外の multi catch
と safe rethrow
ジェネリクスの省略記法
try-with-resources
簡潔な可変長引数メソッド

8. Project Coin 従来の記述
InputStream in = null; OutputStream out = null;
try {
in = new FileInputStream(src);
out = new FileOutputStream(src);
byte[] buf = new byte[1024]; int n;
while((n = in.read(buf)) >= 0) out.write(buf, 0, n);
} catch (IOException ex) {
} finally {
try {
if (in != null) in.close();
if (out != null) out.close();
} catch (IOException ex) {}
}

9. Project Coin try-with-resources
try (InputStream in = new FileInputStream(src);
OutputStream out = new FileOutputStream(src)) {
byte[] buf = new byte[1024];
int n;
while((n = in.read(buf)) >= 0) {
out.write(buf, 0, n);
}
} catch (IOException ex) {
System.err.println(ex.getMessage());
}

10. NIO.2
New Filesystem API
非同期 I/O
SocketChannel のマルチキャスト

11. FileSystem fileSystem.getDefault();
Path src = fileSystem.getPath(”foo.txt”);
Path dest = fileSystem.getPath(”bar.txt”);
// ファイル操作
Files.copy(src, dest);
Files.move(src, dest);
// シンボリックリンクの生成
Path target = fileSystem.getPath(...);
Path link = fileSystem.getPath(...);
Files.createSymbolicLink(link, target);

12. Path startDir = fileSystem.getPath(".");
final String regex = "Test.java";
// ディレクトリツリーの探索
Files.walkFileTree(startDir,
new SimpleFileVisitor<Path>() {
public FileVisitResult visitFile(Path path,
BasicFileAttributes attrs) {
if (Pattern.matches(regex,
path.getFileName().toString())) {
System.out.println("File: " + path);
}
return FileVisitResult.CONTINUE;
}
});

13. InvokeDynamic
新しいバイトコード
invokedynamic
動的型付け言語のメソッドコール
bootstrap, MethodHandle, CallSite

14. Fork/Join Framework
more cores, more tasks
分割統治法 + Work Stealing

15. class FibonacciTask extends RecursiveTask<Integer> {
private final Integer n;
FibonacciTask(Integer n) { this.n = n; }
protected Integer compute() {
if (n <= 1) return n;
// n-1 に対してフィボナッチ数を求める
FibonacciTask f1 = new FibonacciTask(n - 1);
f1.fork();
// n-2 に対してフィボナッチ数を求める
FibonacciTask f2 = new FibonacciTask(n - 2);
// 処理結果を足し合せて、n のフィボナッチ数とする
return f2.compute() + f1.join();
}
}

16. 7
Project Coin
NIO.2
InvokeDynamic
Mid 2011 Fork/Join Framework
Project Lambda
Project Jigsaw 8
Mid 2013

17. 簡単にマルチタスク
もちろん細粒度
Internal Iteration
+
Lambda Expression

18. List<Student> students = ...
double highestScore = 0.0;
for (Student s: students) {
if (s.getGradYear() == 2011) {
if (s.getScore() > highestScore) {
highestScore = s.getScore();
}
}
}

19. List<Student> students = ...
double highestScore =
students.filter(new Predicate<Student>() {
public boolean op(Student s) {
return s.getGradYear() == 2011;
}
}).map(new Mapper<Student、Double>() {
public Double extract(Student s) {
return s.getScore();
}
}).max();

20. List<Student> students = ...
double highestScore =
students.filter(new Predicate<Student>() {
public boolean op(Student s) {
return s.getGradYear() == 2011;
}
}).map(new Mapper<Student、Double>() {
public Double extract(Student s) {
return s.getScore();
}
青字の部分が冗長
}).max();

21. List<Student> students = ...
double highestScore =
students.filter(Student s -> s.getGradYear()
== 2011)
.map(Student s -> s.getScore())
.max();
赤字の部分がラムダ式

22. List<Student> students = ...
double highestScore =
students.filter(s -> s.getGradYear() == 2011)
.map(s -> s.getScore())
.max();
引数の型を省略可

23. List<Student> students = ...
double highestScore =
パラレルに処理
students.parallel()
.filter(s -> s.getGradYear() == 2011)
.map(s -> s.getScore())
.max();

24. Project Jigsaw
Modularity = Grouping
+ Dependence
+ Versioning
+ Encapsulation
+ Optional modules
+ Module aliases
Packaging = Module files
+ Libraries
+ Repositories
+ Native packages

25. ほかにも ...
JavaFX 3.0
Nashorn
HotRockit
Device Suport
Annotation Type
Coin 2

26. Beyond Java SE 8
Iteroperability
Cloud
Ease of Use
Advanced Optimization
Works Everywhere
& with Everything

27. Conclusion
いますぐ使える Java SE 7
NIO.2, G1GC
Java SE 7u4 java.com で配布
あと 1 年で Java SE 8
Lambda, Jigsaw
JavaFX, Nashorn

28. Java SE 7,
そして Java SE 8
Java in the Box
櫻庭 祐一