Java >= 9

Java >= 9

• 1.
  Java >= 9 Modules,Containers and New Things You Can Do In Private
• 2.
  Outline • Java 9 •Java 10 • Java 11 • Versioning • LTS and Support
• 3.
  Java 9
• 4.
  ProcessHandle / ProcessHandle.Info ProcessHandleself = ProcessHandle.current(); long pid = self.getPid(); ProcessHandle.Info info = self.info(); Optional<String[]> args = info.arguments(); Optional<String> cmd = info.commandLine(); Optional<Instant> started = info.startInstant(); Optional<Duration> cpu = info.totalCpuDuration();
• 5.
  ProcessHandle children() Stream<ProcessHandle> children= ProcessHandle.current().children(); children.forEach(handle -> { assertTrue("Could not kill process " + handle.getPid(), handle.destroy()); });
• 6.
  Interface Private Methods interfaceIntrovertInterface { private static String staticPrivate() { return ”personal”; } private String instancePrivate() { return ”library”; } default void invoke() { String result = staticPrivate(); result += ” ”.concat(instancePrivate()); System.out.println(result); } }
• 7.
  Interfaces Now Allow 1.Constant variables 2. Abstract methods 3. Default methods 4. Static methods 5. Private methods 6. Private static methods
• 8.
  Updated try-with-resources Now managefinal or effectively final variables Before: try (PrintWriter writer = new PrintWriter(new File("test.txt"))) { writer.println("Hello World”); } After: PrintWriter writer = new PrintWriter(new File("test.txt")); try(writer){ writer.println(“…”); }
• 9.
  Diamond Operator Extension DiamondOperator <> extended to Anonymous Inner Classes WitnessClass<Integer> fc = new WitnessClass<>(1) { // anonymous inner class impl }; WitnessClass<? extends Integer> fc0 = new WitnessClass<>(1000) { // anonymous inner class impl }; WitnessClass<?> fc1 = new WitnessClass<>(“1”) { // anonymous inner class impl };
• 10.
  New APIs • java.util.Set.of() •Set<String> keys = Set.of("key1", "key2", "key3"); • java.util.Optional.stream() • List<String> filteredList = listOfOptionals.stream() .flatMap(Optional::stream) .collect(Collectors.toList()); • java.awt.image.MultiResolutionImage
• 11.
  Tooling Changes • JShellREPL • JCMD updates • jhat removed • Multi-release jar files • JVM hprof agent removed • Javadoc HTML5 + Search
• 12.
  Other Enhancements • Publish-Subscribefor Reactive Streams (java.util.concurrent.Flow) • Unified JVM Logging • Bonus Incubating Feature – new HTTP Client • Stack Walking API • Variable Handles • In java.lang.invoke - VarHandle and MethodHandles. It provides equivalents of java.util.concurrent.atomic and sun.misc.Unsafe operations on object fields and array elements with similar performance. In Java 9 Modular system sun.misc.Unsafe will not be possible from application code.
• 13.
  Modules • One ofthe biggest changes to Java since Generics • Even Javadoc got an overhaul because of Modules. Note: There are literally books on this topic. • https://javamodularity.com/ • https://www.manning.com/books/the-java-module-system
• 14.
  The Goals ofJSR-376 / Project Jigsaw • Reliable configuration • Strong encapsulation • Scalable platform • Greater platform integrity • Improved performance
• 15.
  module-info.java • Included injar file at the root of the package hierarchy. module <module_name> { }
• 16.
  Keywords - requires •requires <module_name> - allows access to public types exported in the target module • requires transitive <module_name> - any modules depending on this module also depend on the transitive module
• 17.
  Keywords - exports •exports <package_name> - makes public members in a package available to be required. • Qualified export – limits the module to which a package is made available. exports <package_name> to <module_name>
• 18.
  Keywords - uses/ provides • Service Provider Interface keywords. • uses <class_name> - makes the current module a consumer of the specified service class. • provides <class_name> with <class_name_impl> - identifies/registers a class which implements a service class
• 19.
  Keywords - opens/ open • opens <package_name> - allows reflection based access to all members of a specified package. • Qualified open – limits the module to which a package is made opened. opens <package_name> to <module_name> • Open module - defines a module as previously shown but allows runtime access to all packages via reflection open module <module_name> …
• 20.
  Example Module $ java--describe-module java.sql java.sql@9.0.4 exports java.sql exports javax.sql exports javax.transaction.xa requires java.logging transitive requires java.base mandated requires java.xml transitive uses java.sql.Driver
• 21.
  The java.se module
• 22.
  jlink • Make yourown JRE • Includes only the necessary components to run your application • Default JRE size is 200+ MB • Applications built with jlink can be much smaller
• 23.
  Some Caveats • Thisis a (woefully incomplete) overview. • Tooling Support is still being developed • Gradle for example does not currently support building or jlinking modules without the use of an incubating plugin. • Existing libraries may require rework – e.g, repackaged jars. • Module system is easily circumvented by using CLASSPATH instead of MODULEPATH
• 24.
  Java 10
• 25.
  Local Variable TypeInference • var keyword (but it’s not JavaScript) • Before Java 7 • Map<String, List<String>> tagged = new HashMap<String,List<String>>(); • Java 7: • Map<User, List<String>> tagged = new HashMap<>(); • Java 10 • var tagged = new HashMap<User, List<String>>();
• 26.
  Use Cases • Doesexactly what it says it does. • Local variables only, in contexts where type can be inferred. • You can’t do this: • var x = null; • var y; • But you can do this: • var list = new ArrayList<>(); • Inferred as ArrayList<Object> which is probably not what you want.
• 27.
  Better Containerized Behavior •Memory • Before - JVM defaults to 1/4th physical memory of the server. • After - JVM reads memory limits from container cgroup. • Similar issue with CPUs. • JVMs assume they have greater access to resources. • Especially if code uses Runtime.availableProcessors() • Attach Protocol • Before - not possible to attach from host to container JVM. • After - container JVM finds its PID in the root namespace and uses that to watch for JVM attachment.
• 28.
  Under the Hood •Garbage Collector Interface (improve the modularity of various GC implementations) (JEP 304) • Parallel full GC for G1 (improve worst-case latencies with the default collector) (JEP 307) • Experimental Graal Java-based JIT compiler (can be enabled on Linux) (JEP 317) • Remove the Native Header generation tool (javah) (JEP 313)
• 29.
  Under the Hood(cont) • Root Certificates and Certification Authority (JEP 319) • Thread-local Handshakes (Makes it both possible and cheap to stop individual threads and not just all threads or none)(JEP 312) • Heap Allocation on Alternative Memory Devices (JEP 316) • Additional Unicode Language-Tag Extensions (JEP 314)
• 30.
  Java 11
• 31.
  What’s In Java11 • Local Variable Syntax for Lambda Parameters (JEP 323) • Allow var to be used to declare the formal parameters of an implicitly typed lambda expression. • Instead of (var x, var y) -> x.process(y) • We’ll be able to simply write: (x, y) -> x.process(y)
• 32.
  What’s In Java11 • Epsilon: A No-op Garbage Collector (JEP 318) • Dynamic Class File Constants (JEP 309) • "seek[s] to reduce the cost and disruption of creating new forms of materializable class-file constants, which in turn offers language designers and compiler implementors broader options for expressivity and performance."
• 33.
  What’s Not inJava 11 • Java EE and CORBA Modules
• 34.
  Here There BeRanting …
• 35.
  Versioning
• 36.
  JDK Release Cadence •Release every six months • LTS Release every 3 years • 8 is an LTS release • 11 is an LTS release • 17 will be the next LTS release in 2021
• 37.
  Version Identifiers • Java8 is 1.8 • Java 9 is 9.0 • Java 10 is 18.3* • Java 11 is 18.9* *Proposed versioning scheme (year.month)
• 38.
  Long Term Support Forvarying definitions of Support
• 39.
  Public Updates • Supportfor a release ends with the next release. • Java 8 - No updates after Jan. 2019 • Java 9 - No updates after Mar. 2018 (Java 10 release date) • Java 10 - No updates after Sept. 2018 (Java 11 release date) • Java 11 - TBA • should in theory end with the next LTS version 17 in 2021 • but only if you’re paying for support, otherwise, no updates after Java 12
• 40.
  Other Support Options •https://www.azul.com/products/zulu-and-zulu-enterprise/ • https://adoptopenjdk.net/
• 41.
  Questions
• 42.
  Resources • https://docs.oracle.com/javase/9/whatsnew/toc.htm • https://www.pluralsight.com/blog/software-development/java-9-new-features •https://blog.takipi.com/5-features-in-java-9-that-will-change-how-you-develop-software-and-2-that-wont/ • http://www.baeldung.com/new-java-9 • https://www.opsian.com/blog/java-on-docker/ • http://www.oracle.com/technetwork/java/javase/10-relnote-issues-4108729.html • https://dzone.com/articles/java-10-new-features-and-enhancements • https://blog.takipi.com/java-11-will-include-more-than-just-features/ • https://dzone.com/articles/an-early-look-at-features-targeted-for-java-11 • https://medium.com/@afinlay/java-11-sneak-peek-local-variable-type-inference-var-extended-to-lambda-expression- parameters-e31e3338f1fe • http://www.oracle.com/technetwork/java/javase/eol-135779.html • https://jaxenter.com/end-life-comes-early-jdk-8-140824.html