![www.luxoft.com
Java 9 :: Process API
• java.lang.ProcessHandle
• ProcessHandle self = ProcessHandle.current();
• long PID = self.getPid();
• ProcessHandle.Info procInfo = self.info();
• Optional<String[]> args = procInfo.arguments();
• Optional<String> cmd = procInfo.commandLine();
• Optional<Instant> startTime = procInfo.startInstant();
• Optional<Duration> cpuUsage = procInfo.totalCpuDuration();
• Destroying processes:
childProc = ProcessHandle.current().children();
childProc.forEach(procHandle -> {
assertTrue("Could not kill process " + procHandle.getPid(), procHandle.destroy());
});](https://image.slidesharecdn.com/petrogordiievychfromjava9tojava12-190917133053/85/Petro-Gordiievych-From-Java-9-to-Java-12-10-320.jpg)
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Java 12 :: Streams API has new Collector
public static <T,R1,R2,R> Collector<T,?,R> teeing(Collector<? super T,?,R1> downstream1, Collector<?
super T,?,R2> downstream2, BiFunction<? super R1,? super R2,R> merger)
var result = Stream.of("Devoxx", "Voxxed Days", "Code One", "Basel One", "Angular Connect")
.collect(
Collectors.teeing(
Collectors.filtering(n -> n.contains("xx"),
Collectors.toList()),
Collectors.filtering(n -> n.endsWith("One"), Collectors.toList()),
(List<String> list1, List<String> list2) -> List.of(list1, list2)
)
); System.out.println(result);
// -> [[Devoxx, Voxxed Days], [Code One, Basel One]]](https://image.slidesharecdn.com/petrogordiievychfromjava9tojava12-190917133053/85/Petro-Gordiievych-From-Java-9-to-Java-12-31-320.jpg)
Petro Gordiievych "From Java 9 to Java 12"
- 1. www.luxoft.com From Java 9 to Java 12. Brief Overview Petro Gordiievych
- 5. www.luxoft.com Java 9 • Modular system – Jigsaw Project • A new HTTP Client • Process API • Small language modifications • Jshell Command Line Tool • JCMD Sub-Commands • Multi-Resolution Image API • Variable Handles • Publish-Subscribe Framework • Unified JVM Logging • New APIs
- 6. www.luxoft.com Java 9 :: Java Platform Module System (JPMS) • Module—a uniquely named, reusable group of related packages, as well as resources (such as images and XML files) and a module descriptor specifying • the module’s name • the module’s dependencies (that is, other modules this module depends on) • the packages it explicitly makes available to other modules (all other packages in the module are implicitly unavailable to other modules) • the services it offers • the services it consumes • to what other modules it allows reflection
- 7. www.luxoft.com Java 9 :: Modules Types • System Modules – These are the modules listed when we run the list-modules command above. They include the Java SE and JDK modules. • Application Modules – These modules are what we usually want to build when we decide to use Modules. They are named and defined in the compiled module-info.class file included in the assembled JAR. • Automatic Modules – We can include unofficial modules by adding existing JAR files to the module path. The name of the module will be derived from the name of the JAR. Automatic modules will have full read access to every other module loaded by the path. • Unnamed Module – When a class or JAR is loaded onto the classpath, but not the module path, it's automatically added to the unnamed module. It's a catch-all module to maintain backward compatibility with previously-written Java code.
- 8. www.luxoft.com Java 9 :: Module declaration • module com.luxoft.logeeknight { exports com.luxoft.logeeknight.slides; requires com.luxoft.pgordiievych; requires public com.luxoft.calendar; requires guava; } • jlink – allows create custom runtime image
- 9. www.luxoft.com Java 9 :: New HTTP Client HttpURLConnection -> HttpClient (jdk.incubator.http.HttpClient) It supports both HTTP/2 protocol and WebSocket handshake, with performance that should be comparable with the Apache HttpClient, Netty and Jetty. HttpRequest request2 = HttpRequest.newBuilder() .uri(new URI("https://postman-echo.com/get")) .header("key1", "value1") .header("key2", "value2") .GET() .build();
- 10. www.luxoft.com Java 9 :: Process API • java.lang.ProcessHandle • ProcessHandle self = ProcessHandle.current(); • long PID = self.getPid(); • ProcessHandle.Info procInfo = self.info(); • Optional<String[]> args = procInfo.arguments(); • Optional<String> cmd = procInfo.commandLine(); • Optional<Instant> startTime = procInfo.startInstant(); • Optional<Duration> cpuUsage = procInfo.totalCpuDuration(); • Destroying processes: childProc = ProcessHandle.current().children(); childProc.forEach(procHandle -> { assertTrue("Could not kill process " + procHandle.getPid(), procHandle.destroy()); });
- 11. www.luxoft.com Java 9 :: Jshell Command Line tool • Read-Eval-Print Loop (REPL)
- 12. www.luxoft.com Java 9 :: Unified JVM Logging • java -Xlog:gc=debug:file=gc.txt:none ... • jcmd 9615 VM.log output=gc_logs what=gc • -Xlog:help will output possible options and examples. • Messages forwarding: java -Xlog:all=debug:file=application.log -version • Messages decorators: java -Xlog:gc*=debug:stdout:time,uptimemillis,tid -version
- 13. www.luxoft.com Java 9 :: Unified JVM Logging • java -Xlog:gc=debug:file=gc.txt –version 13
- 14. www.luxoft.com Java 9 :: Unified JVM Logging • java -Xlog:gc*=debug:stdout:time,uptimemillis,tid -version 14
- 15. www.luxoft.com Java 9 :: Publish-Subscribe Framework These interfaces correspond to the reactive-streams specification. They apply in both concurrent and distributed asynchronous settings: All (seven) methods are defined in void "one-way" message style. • static interface Flow.Processor<T,R> - A component that acts as both a Subscriber and Publisher. • static interface Flow.Publisher<T> - A producer of items (and related control messages) received by Subscribers. • static interface Flow.Subscriber<T> - A receiver of messages. • static interface Flow.Subscription - Message control linking a Flow.Publisher and Flow.Subscriber.
- 16. www.luxoft.com Java 9 :: Publish-Subscribe Framework @FunctionalInterface public static interface Flow.Publisher<T> { public void subscribe(Flow.Subscriber<? super T> subscriber); } public static interface Flow.Subscriber<T> { public void onSubscribe(Flow.Subscription subscription); public void onNext(T item) ; public void onError(Throwable throwable) ; public void onComplete() ; } public static interface Flow.Subscription { public void request(long n); public void cancel() ; } public static interface Flow.Processor<T,R> extends Flow.Subscriber<T>, Flow.Publisher<R> { }
- 17. www.luxoft.com Java 9 :: New APIs • java.util.Set.of() • Set<String> strKeySet = Set.of("key1", "key2", "key3"); • java.util.Optional.stream() • List<String> filteredList = listOfOptionals.stream() .flatMap(Optional::stream) .collect(Collectors.toList());
- 19. www.luxoft.com Java 10 • Local-Variable Type Inference • Unmodifiable Collections • Optional *.orElseThrow() • Performance Improvements • Container Awareness • Root Certificates • Deprecation and Removals • Time-Based Release Versioning
- 20. www.luxoft.com Java 10 :: Local-Variable Type Inference • Java 9: String message = “Hi there!”; • Java 10: var message = “Hi there!”; • Compiller infers the type of message from the type of initializer present on the right-hand side • var dict = new HashMap<String, String>(); • Illegal to use in cases: • var x; • var emptyList = null; • public var x = “test”; • var p = (String x) -> s.length() < 5; • var arr = {”x”, “y”, “z”};
- 21. www.luxoft.com Java 10 :: Unmodifiable Collections • java.util.List:<E> List<E> copyOf(Collection<? extends E> coll) • java.util.Set:<E> Set<E> copyOf(Collection<? extends E> coll) • java.util.Map:<K,V> Map<K,V> copyOf(Map<? extends K, ? extends V> coll) • UnsupportedOperationException throws
- 22. www.luxoft.com Java 10 :: Time-Based Release Versioning • Each major release of the Java platform will occur every 6 months (March and September) • Update releases will occur every quarter (January, April, July, October) • Long Term Release (LTS) – updates for releases will be available for at least three years • Version format: $FEATURE.$INTERIM.$UPDATE.$PATCH
- 24. www.luxoft.com Java 11 • Local-Variable Syntax for Lambda Parameters • Launch Single-File Source Code Programs (JEP) • HTTP Client • Remove The Java EE and CORBA Module • Dynamic Class-File Constants • The Epsilon GC • Flight Recorder
- 25. www.luxoft.com Java 11 :: Local-Variable Syntax for Lambda Parameters list.stream() .map((var s) -> s.toLowerCase()) .collect(Collectors.toList()); Why? If could be simple: list.stream() .map(s -> s.toLowerCase()) .collect(Collectors.toList()); But: list.stream() .map((@Notnull var s) -> s.toLowerCase()) .collect(Collectors.toList());
- 26. www.luxoft.com Java 11 :: Launch Single-File Source Code Programs (JEP) java HelloWorld.java java -classpath /home/foo/java Hello.java Luxoft Is equal to: javac -classpath /home/foo/java Hello.java java -classpath /home/foo/java Hello Luxoft
- 27. www.luxoft.com Java 11 :: Dynamic Class-File Constants • *.class format extension described support CONSTANT_Dynamic (condy) • Using bootstrap method to define values • java.lang.invoke.ConstantBootstraps
- 29. www.luxoft.com Java 12 • Switch Case • Streams API • Other
- 30. www.luxoft.com Java 12 :: Switch Case T result = switch (arg) { case L1 -> e1; case L2 -> e2; default -> e3; }; int j = switch (day) { case MONDAY -> 0; case TUESDAY -> 1; default -> { int k = day.toString().length(); int result = f(k); break result; } };
- 31. www.luxoft.com Java 12 :: Streams API has new Collector public static <T,R1,R2,R> Collector<T,?,R> teeing(Collector<? super T,?,R1> downstream1, Collector<? super T,?,R2> downstream2, BiFunction<? super R1,? super R2,R> merger) var result = Stream.of("Devoxx", "Voxxed Days", "Code One", "Basel One", "Angular Connect") .collect( Collectors.teeing( Collectors.filtering(n -> n.contains("xx"), Collectors.toList()), Collectors.filtering(n -> n.endsWith("One"), Collectors.toList()), (List<String> list1, List<String> list2) -> List.of(list1, list2) ) ); System.out.println(result); // -> [[Devoxx, Voxxed Days], [Code One, Basel One]]
- 32. www.luxoft.com Java 12 :: Other • InputStream skipNBytes(long n) • java.lang.constant • java.lang.Character • java.lang.Class – arrayType() • java.lang.String (indent(), transform())
- 33. www.luxoft.com 33www.luxoft.com References • https://www.oracle.com/corporate/features/understanding-java-9-modules.html • https://www.baeldung.com/java-9-http-client • https://docs.oracle.com/javase/9/docs/api/jdk/incubator/http/HttpClient.html • https://openjdk.java.net/jeps/325 • https://docs.oracle.com/en/java/javase/12/docs/api/java.base/java/util/stream/Collectors.html • https://dzone.com/articles/a-new-jdk12-stream-api-collection-collectorsteeing • https://www.baeldung.com/new-java-9 • https://docs.oracle.com/javase/9/docs/api/java/util/concurrent/Flow.html • https://openjdk.java.net/jeps/110 • https://openjdk.java.net/projects/jigsaw/