Java 9 Features

> ~ jshell
|  Welcome to JShell -- Version 9-ea
|  For an introduction type: /help intro

jshell> 3 + 4 * 7
$1 ==> 31

jshell> int add(int a, int b) {
...>   return a+b;
...> }
|  created method add(int,int)

jshell> add(25, $1)
$3 ==> 56

"C:\Program Files\Java\jdk-9\bin\jdeps"
-summary
guava-23.0.jar

"C:\Program Files\Java\jdk-9\bin\jdeps"
--dot-output
-summary
guava-23.0.jar

"C:\Program Files\Java\jdk-9\bin\jmod"
create --class-path target\classes
target\jmods\org.wildcraft.tooling.jmod

"C:\Program Files\Java\jdk-9\bin\jlink"
--module-path "%JAVA_HOME%\jmods";target\jmods
--add-modules org.wildcraft.tooling
--output target/executable

"C:\Program Files\Java\jdk-9\bin\jdeprscan"
guava-23.0.jar

"C:\Program Files\Java\jdk-9\bin\jdeprscan"
--release 9
--list

JAR content root
  A.class
  B.class
  C.class
  D.class
  META-INF
     MANIFEST.MF
     versions
        9
           A.class
           B.class
        10
           A.class

/* Comment sections would break ... */
List<Integer> listOfNumbers = List.of(1, 2, 3, 4, 5
                                        /*, null*/);

Set<Integer> setOfNumbers = Set.of(1, 2, 3, 4, 5/*, 1*/);

Map<String, String> mapOfString =
    Map.of("key1", "value1", "key2", "value2");

Map<String, String> moreMapOfString =
    Map.ofEntries(
        Map.entry("key1", "value1"),
        Map.entry("key2", "value2")/*,
        Map.entry("key1", "value3")*/
);

Stream.of("a", "b", "c", "", "e")
                .takeWhile(s -> !s.isEmpty())
                .forEach(System.out::print);

Stream.of("a", "b", "c", "de", "f")
                .dropWhile(s -> s.length() <= 1)
                .forEach(System.out::print);

Stream.iterate(1, i -> 2 * i)
                .filter(i->i<=10)
                .forEach(System.out::println);

Stream.iterate(1, i -> i <= 10, i -> 2 * i)
                .forEach(System.out::println);

FileReader fileReader
                  = new FileReader(new File(fileURI));
BufferedReader bufferedReader
                  = new BufferedReader(fileReader);
try (fileReader; bufferedReader) {

    String line = "";
    while ((line = bufferedReader.readLine()) != null) {
        fileContent =line;
    }
}

<T> Box<T> createBox(T content) {
    // we have to put the `T` here :(
    return new Box<T>(content) { };
}

<T> Box<T> createBox(T content) {
    // Java 9 can infer `T`
    // because it is a denotable type
    return new Box<>(content) { };
}

Box<?> createCrazyBox(Object content) {
    List<?> innerList = Arrays.asList(content);
    // we can't do the following
    // because the inferred type is non-denotable
    return new Box<List<?>>(innerList) { };
}

@Deprecated(since = "3.0")
public class Asset {

    @Deprecated(since = "1.0", forRemoval=true)
    public void getAssertValue() {

    }
}

@SafeVarargs
private <T> Optional<T> privateNonStatic(T... args) {
    if (args.length == 0)
        return Optional.empty();
    else
        return Optional.of(args[0]);
}

/**
 * The HTTP API functions asynchronously
 * and synchronously. In
 * asynchronous mode,
 * work is done in threads (ExecutorService).
 */
public static void main(String[] args) throws Exception {
  HttpClient.getDefault()
    .request(URI.create("https://www.exxcellent.de"))
    .GET()
    .responseAsync() // CompletableFuture :D
    .thenAccept(httpResponse ->
        out.println(httpResponse
        .body(HttpResponse.asString()))
    );
  Thread.sleep(999); // Give worker thread some time.
}