Java 9 - what else is new?

Most Java developers have heard about Jigsaw - the new Java module system. But what else does Java 9 provide when it comes to new features and changes?

Transcript

1. Java 9 - what else is new? Jan Fredrik Wedén 1 / 40
2. Java Shell (jshell)! 2 / 40
3. jshell - some features Trying out snippets of code Tab completion for snippets and commands Changing definitions Forward references Editing and searching in shell, like you expect External editor with /edit Loading external code through classpath or module path Saving and loading external scripts 3 / 40
4. Some jshell commands /exit - first thing to know is how to get out (^D also works) /help - list of available commands /list - lists all snippets /save /open - save and open snippets to and from disk /vars /types /methods - list current vars etc 4 / 40
5. Immutable collections 5 / 40
6. Collections (old school) Set<String> set = new HashSet<>(); set.add("Java"); set.add("eight"); set.add("collections"); set = Collections.unmodifiableSet(set); 6 / 40
7. Collections (old school) Set<String> set = new HashSet<>(); set.add("Java"); set.add("eight"); set.add("collections"); set = Collections.unmodifiableSet(set); Set<String> set = Collections.unmodifiableSet(new HashSet<>(Arrays.asList("Java", "eight", "collections"))); 7 / 40
8. Collections (old school) Set<String> set = new HashSet<>(); set.add("Java"); set.add("eight"); set.add("collections"); set = Collections.unmodifiableSet(set); Set<String> set = Collections.unmodifiableSet(new HashSet<>(Arrays.asList("Java", "eight", "collections"))); Set<String> set = Collections.unmodifiableSet(new HashSet<String>() {{ add("Java"); add("eight"); add("collections"); }}); 8 / 40
9. Collections (old school) Set<String> set = new HashSet<>(); set.add("Java"); set.add("eight"); set.add("collections"); set = Collections.unmodifiableSet(set); Set<String> set = Collections.unmodifiableSet(new HashSet<>(Arrays.asList("Java", "eight", "collections"))); Set<String> set = Collections.unmodifiableSet(new HashSet<String>() {{ add("Java"); add("eight"); add("collections"); }}); Set<String> set = Collections.unmodifiableSet(Stream.of("Java", "eight", "collections").collect(toSet())); 9 / 40
10. Collections (old school) Set<String> set = new HashSet<>(); set.add("Java"); set.add("eight"); set.add("collections"); set = Collections.unmodifiableSet(set); Set<String> set = Collections.unmodifiableSet(new HashSet<>(Arrays.asList("Java", "eight", "collections"))); Set<String> set = Collections.unmodifiableSet(new HashSet<String>() {{ add("Java"); add("eight"); add("collections"); }}); Set<String> set = Collections.unmodifiableSet(Stream.of("Java", "eight", "collections").collect(toSet())); Guava anyone?? 10 / 40
11. New collection factory methods Set<String> mySet = Set.of("Java", "nine", "collections"); 11 / 40
12. New collection factory methods Set<String> mySet = Set.of("Java", "nine", "collections"); List<String> myList = List.of("Java", "nine", "collections"); 12 / 40
13. New collection factory methods Set<String> mySet = Set.of("Java", "nine", "collections"); List<String> myList = List.of("Java", "nine", "collections"); Map<String,String> myMap = Map.of("Duke", "Java", "coolest", "nine", "better", "collections"); 13 / 40
14. New collection factory methods Set<String> mySet = Set.of("Java", "nine", "collections"); List<String> myList = List.of("Java", "nine", "collections"); Map<String,String> myMap = Map.of("Duke", "Java", "coolest", "nine", "better", "collections"); Map<String,String> myEntryMap = Map.ofEntries( Map.entry("Duke", "Java"), Map.entry("coolest", "nine"), Map.entry("better", "collections") ); 14 / 40
15. Such collections Are structurally immutable (mutators throw UnsupportedOperationException) Disallow null elements (and keys) Are serializable if all elements (and keys) are Sets and Maps throw IllegalArgumentException for duplicate elements/keys at creation time Iteration order of Lists behave as expected and is undefined for Sets and Maps Are value based (you should not rely on ==) 15 / 40
16. Optional stu 16 / 40
17. New methods on Optional public void ifPresentOrElse (Consumer<? super T> action, Runnable emptyAction) 17 / 40
18. New methods on Optional public void ifPresentOrElse (Consumer<? super T> action, Runnable emptyAction) public Optional<T> or (Supplier<? extends Optional<? extends T>> supplier) 18 / 40
19. New methods on Optional public void ifPresentOrElse (Consumer<? super T> action, Runnable emptyAction) public Optional<T> or (Supplier<? extends Optional<? extends T>> supplier) public Stream<T> stream () 19 / 40
20. New methods on Optional public void ifPresentOrElse (Consumer<? super T> action, Runnable emptyAction) public Optional<T> or (Supplier<? extends Optional<? extends T>> supplier) public Stream<T> stream () List<Optional<String>> optionals = List.of( Optional.of("Java"), Optional.of("nine"), Optional.empty(), Optional.of("Optional") ); System.out.println("Optionals in list:") optionals.stream().forEach(System.out::println) System.out.println("All Optional values (or null):") optionals.stream().map(o -> o.orElse(null)).forEach(System.out::println) System.out.println("Only present Optional values:") optionals.stream().flatMap(Optional::stream).forEach(System.out::println) 20 / 40
21. I/O and resources 21 / 40
22. I/O and resources "Effectively final" variables allowed in try-with-resources void copyFile(InputStream in, OutputStream out) throws IOException { try (in; out) { in.transferTo(out); } } InputStream inFile = Files.newInputStream(Paths.get("in.txt")); OutputStream outFile = Files.newOutputStream(Paths.get("out.txt")); copyFile(inFile, outFile); try (InputStream inFileAgain = Files.newInputStream(Paths.get("in.txt"));) { byte[] allBytes = inFileAgain.readAllBytes(); } 22 / 40
23. I/O and resources New methods on InputStream void copyFile(InputStream in, OutputStream out) throws IOException { try (in; out) { in.transferTo(out); } } InputStream inFile = Files.newInputStream(Paths.get("in.txt")); OutputStream outFile = Files.newOutputStream(Paths.get("out.txt")); copyFile(inFile, outFile); try (InputStream inFileAgain = Files.newInputStream(Paths.get("in.txt"));) { byte[] allBytes = inFileAgain.readAllBytes(); } 23 / 40
24. HTTP/2 24 / 40
25. New HTTP client in Java! Supports HTTP/2 and WebSockets Supports sync and async request modes Supports multiple HTTP/2 push responses Replaces the legacy HttpURLConnection 25 / 40
26. Caveats Incubator module Not all (expected) features currently available Apparently vulnerable to attacks (BREACH and CRIME) Apparently sloppy about cookie security HTTP/1.1 encryption 26 / 40
27. HttpClient Example import jdk.incubator.http.*; HttpClient.newHttpClient() .sendAsync( HttpRequest.newBuilder(URI.create("https://www.google.no")) .GET() .build(), HttpResponse.BodyHandler.asString()) .thenAccept(response -> System.out.println(response.statusCode())); 27 / 40
28. HttpClient Example import jdk.incubator.http.*; HttpClient.newHttpClient() .sendAsync( HttpRequest.newBuilder(URI.create("https://www.google.no")) .GET() .build(), HttpResponse.BodyHandler.asString()) .thenAccept(response -> System.out.println(response.statusCode())); Must add incubator module to jshell When starting: $ jshell --add-modules jdk.incubator.httpclient Or inside jshell jshell> /env -add-modules jdk.incubator.httpclient 28 / 40
29. Deprecation Stu is actually going to be removed from Java! 29 / 40
30. Enhanced @Deprecated Added since attribute Added forRemoval attribute @Deprecated(since="9", forRemoval=true) 30 / 40
31. New deprecations Applet API Observer and Observable boxed primitive constructors Object.finalize java.security.acl API com.sun.jarsigner package policytool 31 / 40
32. Stu to be gone CORBA sun.misc.Unsafe.defineClass pre 1.2 SecurityManager methods java.activation java.se.ee java.transaction (subset of JTA to support CORBA interoperation) java.xml.bind java.xml.ws java.xml.ws.annotation 32 / 40
33. Stu gone in 9 _ as identifier hprof and jhat tools Demos and Samples 33 / 40
34. In other news 34 / 40
35. Streams Stream (and primitive streams) now have takeWhile(Predicate) dropWhile(Predicate) //Expected 0,1,2,3,4 IntStream.of(0,1,2,3,4,5,6,7,8,9).takeWhile(i -> i < 5).forEach(System.out::println) //Expected 5,6,7,8,9 IntStream.of(0,1,2,3,4,5,6,7,8,9).dropWhile(i -> i < 5).forEach(System.out::println) 35 / 40
36. Multi-release JARs jar root - A.class - B.class - C.class - D.class - META-INF - versions - 9 - A.class - B.class - 10 - A.class 36 / 40
37. Private methods in interfaces interface Greeter { ... default void greetSomeone(String personName, boolean female) { System.out.println("Hi " + getTitle(female) + " " + personName); } default void farewellSomeone(String personName, boolean female) { System.out.println("Bye " + getTitle(female) + " " + personName); } private String getTitle(boolean female) { return female ? "Ms" : "Mr"; } } 37 / 40
38. Finally Process import statements correctly javac --release N (no more source and target versions, rt.jar etc) Flow class (with Publisher, Subscriber, Processor, Subscription for reactive streams) HTML5 JavaDoc (with search) UDP security (DTLS) UTF-8 property files and Unicode 7.0 support New version string schema for all JDK $MAJOR.$MINOR.$SECURITY.$PATCH 38 / 40
39. Thanks! @jfweden janwe.github.io/java9-presentation/ github.com/janwe/java9-presentation 39 / 40
40. Resources and inspiration JavaZone 2017: Java SE 9, and its hidden treasures walkthrough https://docs.oracle.com/javase/9/jshell/toc.htm http://openjdk.java.net/projects/jdk9/ http://www.oracle.com/technetwork/java/javase/9-deprecated-features-3745636.html https://docs.oracle.com/javase/9/docs/api/overview-summary.html https://dzone.com/articles/java-9-besides-modules https://dzone.com/articles/java-9-http-20 40 / 40