Java 9 language and core API updates

Transcript

1. JAVA 9 LANGUAGE & CORE API UPDATES @ANTONARHIPOV
2. JAVA 9 SCHEDULE •16th March 2017 Rampdown Phase 2 •6th July 2017 Final Release Candidate •27th July 2017 General Availability
3. THINGS I CAN’T TALK ABOUT YET Detailed performance metrics Experience based analysis
4. http://openjdk.java.net/projects/jdk9/
5. AGENDA • JEP-213: Milling project coin • JEP-102: Process API updates • JEP-266: More concurrency updates • JEP-269: Convenience factory methods for collections • JEP-277: Enhanced deprecation • JEP-259: Stack-Walking API
6. AGENDA • Date & Time API enhancements • Stream/Optional API enhancements • JShell
7. JSR 376: JAVA PLATFORM MODULE SYSTEM
8. • http://openjdk.java.net/projects/jigsaw/ • JEP 200: The Modular JDK • JEP 220: Modular Run-Time Images • JEP 260: Encapsulate Most Internal APIs • JEP 261: Module System • JEP 282: jlink: The Java Linker JSR 376: JAVA PLATFORM MODULE SYSTEM
11. DIAMOND <> OPERATOR WITH ANONYMOUS INNER CLASSES
12. DIAMOND <> OPERATOR WITH ANONYMOUS INNER CLASSES List<String> strings = new ArrayList<String>(){{ add("a"); add("b"); add("c"); }}; Java 8
13. DIAMOND <> OPERATOR WITH ANONYMOUS INNER CLASSES List<String> strings = new ArrayList<String>(){{ add("a"); add("b"); add("c"); }}; Java 8 List<String> strings = new ArrayList<>(){{ add("a"); add("b"); add("c"); }}; Java 9
14. ENHANCED TRY-WITH-RESOURCES
15. ENHANCED TRY-WITH-RESOURCES try (BufferedReader reader = Files.newBufferedReader(…)) { //… } Java 8
16. ENHANCED TRY-WITH-RESOURCES try (BufferedReader reader = Files.newBufferedReader(…)) { //… } Java 8 BufferedReader reader = Files.newBufferedReader(…); try (BufferedReader reader1 = reader) { //… }
17. ENHANCED TRY-WITH-RESOURCES Java 9 BufferedReader reader = Files.newBufferedReader(…); try (reader) { //… } try (BufferedReader reader = Files.newBufferedReader(…)) { //… } Java 8 BufferedReader reader = Files.newBufferedReader(…); try (BufferedReader reader1 = reader) { //… }
18. int _ = 1; UNDERSCORE _ IS NOT ALLOWED AS AN IDENTIFIER NAME
19. int _ = 1; UNDERSCORE _ IS NOT ALLOWED AS AN IDENTIFIER NAME Java 8: warning: '_' used as an identifier int _ = 1; ^ (use of '_' as an identifier might not be supported in releases after Java SE 8)
20. int _ = 1; UNDERSCORE _ IS NOT ALLOWED AS AN IDENTIFIER NAME Java 9: error: as of release 9, '_' is a keyword, and may not be used as an identifier int _ = 1; ^
21. public class UnderscoreDemo { public static void main(String[] __) { for (int ___ = 0; ___ < __.length; ___++) System.out.println(__[___]); } } UNDERSCORE _ IS NOT ALLOWED AS AN IDENTIFIER NAME
22. UNDERSCORE _ IS NOT ALLOWED AS AN IDENTIFIER NAME JEP-302: Lambda leftovers (Java 10?) BiFunction<Integer, String, String> biss = (i, _) -> String.valueOf(i);
23. UNDERSCORE _ IS NOT ALLOWED AS AN IDENTIFIER NAME JEP-302: Lambda leftovers (Java 10?) BiFunction<Integer, String, String> biss = (i, _) -> String.valueOf(i);
24. PRIVATE METHODS IN INTERFACES interface SomeInterface { default void methodA() {} private void methodB() {} private static void methodC(){} private default methodD(){} } // since Java 8 // new in Java 9 // new in Java 9 // error: cannot be // private and default
25. @SAFEVARARGS ON PRIVATE METHODS List<String> list1 = singletonList("Hi"); List<String> list2 = singletonList("Hi"); call(list1, list2); static void call(List<String>... lists) { String s = lists[0].get(0); System.out.println(s); }
26. @SAFEVARARGS ON PRIVATE METHODS List<String> list1 = singletonList("Hi"); List<String> list2 = singletonList("Hi"); call(list1, list2); static void call(List<String>... lists) { String s = lists[0].get(0); System.out.println(s); } warning: [unchecked] Possible heap pollution from parameterized vararg type List<String>: static void call(List<String>... lists) { warning: [unchecked] unchecked generic array creation for varargs parameter of type List<String>[]: call(myList1, myList2);
27. @SAFEVARARGS ON PRIVATE METHODS List<String> list1 = singletonList("Hi"); List<String> list2 = singletonList("Hi"); call(list1, list2); @SafeVarargs static void call(List<String>... lists) { String s = lists[0].get(0); System.out.println(s); }
28. @SAFEVARARGS ON PRIVATE METHODS List<String> list1 = singletonList("Hi"); List<String> list2 = singletonList("Hi"); call(list1, list2); @SafeVarargs private void call(List<String>... lists) { String s = lists[0].get(0); System.out.println(s); } error: Invalid SafeVarargs annotation. Instance method call(List<String>...) is not final. private void call(List<String>... stringLists) { ^ Java 8:
29. @SAFEVARARGS ON PRIVATE METHODS List<String> list1 = singletonList("Hi"); List<String> list2 = singletonList("Hi"); call(list1, list2); @SafeVarargs private void call(List<String>... lists) { String s = lists[0].get(0); System.out.println(s); } Java 9: O.K.
30. CORE THE
31. PROCESS API UPDATES
32. PROCESS API UPDATES RuntimeMXBean runtimeMXBean = ManagementFactory.getRuntimeMXBean(); String name = runtimeMXBean.getName(); String pid = name.split("@")[0]; Java 8:
33. PROCESS API UPDATES RuntimeMXBean runtimeMXBean = ManagementFactory.getRuntimeMXBean(); String name = runtimeMXBean.getName(); String pid = name.split("@")[0]; Java 8: long pid = ProcessHandle.current().getPid(); Java 9:
34. PROCESS API UPDATES RuntimeMXBean runtimeMXBean = ManagementFactory.getRuntimeMXBean(); String name = runtimeMXBean.getName(); String pid = name.split("@")[0]; Java 8: long pid = ProcessHandle.current().getPid(); Java 9: Stream<ProcessHandle> handles = ProcessHandle.allProcesses();
35. https://github.com/zeroturnaround/zt-exec ZT PROCESS EXECUTOR new ProcessExecutor() .command("java", "-version") .redirectOutput(Slf4jStream.of("MyProcess").asInfo()) .execute();
36. KILL ‘EM ALL! void cleanupApplication(String applicationName) { ProcessHandle .allProcesses() .filter(process -> isApplication(applicationName, process)) .forEach(process -> process.info().command().ifPresent(command -> closeAndLog(process, command))); } void closeAndLog(ProcessHandle process, String command) { String status = process.destroyForcibly() ? " Success!" : " Failed"; System.out.println("Killing ... " + command + status); } boolean isApplication(final String appName, final ProcessHandle process) { return process.info().command().filter(command -> command.contains(appName)).isPresent(); }
37. https://github.com/zeroturnaround/zt-process-killer ZT PROCESS KILLER int pid = Integer.parseInt( FileUtils.readFileToString( new File("pidfile"))); PidProcess process = Processes.newPidProcess(pid); ProcessUtil.destroyGracefullyOrForcefullyAndWait(process, 30, TimeUnit.SECONDS, 10, TimeUnit.SECONDS);
38. MORE CONCURRENCY UPDATES
39. FACTORY METHODS FOR COLLECTIONS Set.of("a", "b", "c"); List.of("a", "b", "c"); Map.of(1, "val1", 2, "val2", 3, "val3");
40. FACTORY METHODS FOR COLLECTIONS Set<String> set = new HashSet<>(); set.add("a"); set.add("b"); set.add("c"); set = Collections.unmodifiableSet(set);
41. FACTORY METHODS FOR COLLECTIONS Set<String> set = new HashSet<>(); set.add("a"); set.add("b"); set.add("c"); set = Collections.unmodifiableSet(set); Set<String> set = Collections.unmodifiableSet( new HashSet<>(Arrays.asList("a", "b", "c")));
42. FACTORY METHODS FOR COLLECTIONS Set<String> set = new HashSet<>(); set.add("a"); set.add("b"); set.add("c"); set = Collections.unmodifiableSet(set); Set<String> set = Collections.unmodifiableSet( new HashSet<>(Arrays.asList("a", "b", "c"))); Set<String> set = Collections.unmodifiableSet( Stream.of("a", "b", "c").collect(toSet()));
43. FACTORY METHODS FOR COLLECTIONS Set<String> set = new HashSet<>(); set.add("a"); set.add("b"); set.add("c"); set = Collections.unmodifiableSet(set); Set<String> set = Collections.unmodifiableSet( new HashSet<>(Arrays.asList("a", "b", "c"))); Set<String> set = Collections.unmodifiableSet( Stream.of("a", "b", "c").collect(toSet())); Set<String> set = Set.of("a", "b", "c");
44. @Deprecated
45. @Deprecated(since="9", forRemoval=true)
46. @Deprecated(since="9", forRemoval=true) Still no description or info
49. STACK-WALKING API StackWalker VS Thread::getStackTrace • Filter / asset / skip certain frames • Get the instance of declaring class itself • Get either a short stack trace or complete stack trace
50. STACK-WALKING API StackWalker walker = StackWalker.getInstance(RETAIN_CLASS_REFERENCE); List<StackWalker.StackFrame> stack = walker.walk( s -> s.collect(Collectors.toList()) );
51. STACK-WALKING API StackWalker walker = StackWalker.getInstance(RETAIN_CLASS_REFERENCE); List<StackWalker.StackFrame> stack = walker.walk( s -> s.collect(Collectors.toList()) ); List<StackWalker.StackFrame> stack = walker.walk( s -> s.filter(f -> interestingClasses.contains( f.getDeclaringClass())).findFirst() );
52. DATE & TIME API IMPROVEMENTS
53. DATE & TIME API IMPROVEMENTS LocalDate now = LocalDate.now(); // 2017-04-20 LocalDate java9release = LocalDate.of(2017, Month.JULY, 27); now.datesUntil(java9release); JDK-8146218 - Add LocalDate.datesUntil method producing Stream
54. DATE & TIME API IMPROVEMENTS now.datesUntil(java9release, Period.ofDays(3)); LocalDate now = LocalDate.now(); // 2017-04-20 LocalDate java9release = LocalDate.of(2017, Month.JULY, 27); now.datesUntil(java9release); JDK-8146218 - Add LocalDate.datesUntil method producing Stream
55. DATE & TIME API IMPROVEMENTS JDK-8146218 - Add LocalDate.datesUntil method producing Stream LocalDate now = LocalDate.now(); // 2017-04-20 LocalDate java9release = LocalDate.of(2017, Month.JULY, 27); now.datesUntil(java9release); now.datesUntil(java9release, Period.ofDays(3)) .forEach(out::println);
56. DATE & TIME API IMPROVEMENTS JDK-8146218 - Add LocalDate.datesUntil method producing Stream LocalDate now = LocalDate.now(); // 2017-04-20 LocalDate java9release = LocalDate.of(2017, Month.JULY, 27); now.datesUntil(java9release); now.datesUntil(java9release, Period.ofDays(3)) .forEach(out::println); 2017-04-20 2017-04-23 2017-04-26 2017-05-29 …
57. DATE & TIME API IMPROVEMENTS JDK-8142936 - Duration methods for days, hours, minutes, seconds, etc. Duration#toDaysPart() Duration#toHoursPart() Duration#toMinutesPart() Duration#toSecondsPart() Duration#toMillisPart() Duration#toNanosPart()
58. DATE & TIME API IMPROVEMENTS JDK-8142936 - Duration methods for days, hours, minutes, seconds, etc. Duration.ofMinutes(15000).toDaysPart(); // 10
59. DATE & TIME API IMPROVEMENTS JDK-8142936 - Duration methods for days, hours, minutes, seconds, etc. Duration.ofMinutes(15000).toDaysPart(); // 10 JDK-8148849 - Truncating Duration. Duration.ofMinutes(15000).truncatedTo(ChronoUnit.DAYS); // 10
60. DATE & TIME API IMPROVEMENTS JDK-8142936 - Duration methods for days, hours, minutes, seconds, etc. Duration.ofMinutes(15000).toDaysPart(); // 10 JDK-8148849 - Truncating Duration. Duration.ofMinutes(15000).truncatedTo(ChronoUnit.DAYS); // 10 JDK-8032510 - Add Duration.dividedBy(Duration) Duration.ofDays(10).dividedBy(Duration.ofMinutes(1000)); // 14
61. STREAM/OPTIONAL API ENHANCEMENTS
62. OPTIONAL#GET
63. OPTIONAL#GET http://mail.openjdk.java.net/pipermail/core-libs-dev/2016-April/040484.html Deprecated?
64. OPTIONAL#GET http://mail.openjdk.java.net/pipermail/core-libs-dev/2016-April/040484.html Deprecated? Optional<String> optional = getData(); if (optional.isPresent()) { doSomething(optional.get()); } else { doSomethingElse(); }
65. OPTIONAL#GET
66. OPTIONAL#GET http://mail.openjdk.java.net/pipermail/core-libs-dev/2016-April/040484.html Deprecated?
67. OPTIONAL#GET http://mail.openjdk.java.net/pipermail/core-libs-dev/2016-April/040484.html Deprecated? Optional<String> optional = getData(); if (optional.isPresent()) { doSomething(optional.get()); } else { doSomethingElse(); }
68. OPTIONAL#GET http://mail.openjdk.java.net/pipermail/core-libs-dev/2016-April/040484.html Deprecated? Optional<String> optional = getData(); if (optional.isPresent()) { doSomething(optional.get()); } else { doSomethingElse(); } optional.ifPresentOrElse( this::doSomething, this::doSomethingElse );
69. OPTIONAL#GET http://mail.openjdk.java.net/pipermail/core-libs-dev/2016-April/040484.html Deprecated?
70. OPTIONAL#GET http://mail.openjdk.java.net/pipermail/core-libs-dev/2016-April/040484.html Deprecated? streamOfOptionals.filter(Optional::isPresent).map(Optional::get);
71. OPTIONAL#GET http://mail.openjdk.java.net/pipermail/core-libs-dev/2016-April/040484.html Deprecated? streamOfOptionals.filter(Optional::isPresent).map(Optional::get); streamOfOptionals.flatMap(Optional::stream);
72. OPTIONAL#OR
73. OPTIONAL#OR Optional<User> user = findUserById(42) .or(() -> findUserByName("Anton"));
74. OPTIONAL#OFNULLABLE
75. OPTIONAL#OFNULLABLE Stream.of("Anton", "Cas", "Ethan") .flatMap(n -> Stream.ofNullable(findUserByName(n))) .collect(Collectors.toList());
76. STREAM#TAKEWHILE & #DROPWHILE
77. Stream.of(1, 2, 3, 4, 5, 1, 2) .takeWhile(i -> i < 3) .forEach(out::println); STREAM#TAKEWHILE & #DROPWHILE
78. Stream.of(1, 2, 3, 4, 5, 1, 2) .takeWhile(i -> i < 3) .forEach(out::println); 1 2 STREAM#TAKEWHILE & #DROPWHILE
79. Stream.of(1, 2, 3, 4, 5, 1, 2) .takeWhile(i -> i < 3) .forEach(out::println); Stream.of(1, 2, 3, 4, 5, 1, 2) .dropWhile(i -> i < 3) .forEach(out::println); 1 2 STREAM#TAKEWHILE & #DROPWHILE
80. Stream.of(1, 2, 3, 4, 5, 1, 2) .takeWhile(i -> i < 3) .forEach(out::println); Stream.of(1, 2, 3, 4, 5, 1, 2) .dropWhile(i -> i < 3) .forEach(out::println); 1 2 3 4 5 1 2 STREAM#TAKEWHILE & #DROPWHILE
81. STREAM#ITERATE
82. STREAM#ITERATE Stream.iterate(1, i -> i <= 16, i -> 2 * i) .forEach(out::println);
83. 1 2 4 8 16 STREAM#ITERATE Stream.iterate(1, i -> i <= 16, i -> 2 * i) .forEach(out::println);
84. STREAM#ITERATE
85. STREAM#ITERATE Stream.iterate(2L, n -> n + 1)
86. STREAM#ITERATE Stream.iterate(2L, n -> n + 1) .filter(n -> n % 2 == 0)
87. STREAM#ITERATE Stream.iterate(2L, n -> n + 1) .filter(n -> n % 2 == 0) .skip(1000) .limit(3) .forEach(System.out::println);
88. 2002 2004 2006 STREAM#ITERATE Stream.iterate(2L, n -> n + 1) .filter(n -> n % 2 == 0) .skip(1000) .limit(3) .forEach(System.out::println);