Java-Funktionshandbuch 8-14

Es bietet alles, was Sie über die verschiedenen Versionen und Funktionen von Java wissen müssen.

Java 8, Java 11, Java 13, Java 14 - was ist der Unterschied?

In diesem Handbuch erhalten Sie praktische Informationen zum Auffinden und Installieren der neuesten Java-Version, zum Verständnis der Unterschiede zwischen Java-Distributionen (AdoptOpenJdk, OpenJDK, OracleJDK usw.) und um einen Überblick über Java-Funktionen einschließlich Java-Versionen zu erhalten 8-14.

17 Java
Julegg
java-14 . ?

09 2020 .

-, , Java .

TL;DR . ?

AdoptOpenJDK, Java, . , , , - Java.

TL;DR (. too long; didn't read — , )

Java?

2020 Java 14 Java.

Java ?

Java 6 . , Java 15 2020 , Java 16 2021 . Java , 3-5 . :

:

• Java 8 (. « Java 8?» ). , Java 8.
• Java 1.5 ( 2004 .) 1.6 ( 2006 .) — , !
• , IDE, , Java 11 (LTS) Java 14.
• Android, Java Java 7, Java 8. Kotlin.

Java 8?

, Java 8. :

• (Maven, Gradle ..) Java > 8 . , , Java 9+, «reflective access» Java, « », .
• Java 8 JDK- Oracle, . 2019 Oracle , , , , «Java », — . , « Java» .
• , LTS, , .

, ( , , ) .

Java 1.X?

Java 9 . , Java 8 1.8, Java 5 1.5 .. java -version , :

c:\Program Files\Java\jdk1.8.0_191\bin>java -version
java version "1.8.0_191" (1)
Java(TM) SE Runtime Environment (build 1.8.0_191-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.191-b12, mixed mode)

Java 8. Java 9 , Java 1.x. :

c:\Program Files\Java\jdk11\bin>java -version
openjdk version "11" 2018-09-25 (1)
OpenJDK Runtime Environment 18.9 (build 11+28)
OpenJDK 64-Bit Server VM 18.9 (build 11+28, mixed mode)

Java?

?

, , , Python 2–3, , Java.

Java , . , Java 5 8 Java 8-14 — , .

, , , Java 14, Java 8 JVM.

:

• «» Java, Java 12.
• , Java 8.
• , , Java 9-14, , .

Java?

« Java 8-14» .

, : , (3-5 , Java 8) .

, Java 9-14.

JRE JDK?

Java. «Java»?

-, JRE (Java Runtime Environment) JDK (Java Development Kit).

, JRE, Java. JRE , , Java (JVM) «java».

Java JDK. JDK , JRE, javac , javadoc ( Java) jdb ( Java).

, ?

Java 8 - Oracle JRE JDK , JDK JRE . Java 9 , JDK. JDK , JRE.

, (. « Java») - JRE, , JDK. , Java JDK .

Java JDK?

Java-Docker, MSI . , Java — .zip; .

, , Java , — jdk-{5-14}.zip. .

Java :

Directory C:\dev\jdk-11
12.11.2019  19:24    <DIR>          .
12.11.2019  19:24    <DIR>          ..
12.11.2019  19:23    <DIR>          bin
12.11.2019  19:23    <DIR>          conf
12.11.2019  19:24    <DIR>          include
12.11.2019  19:24    <DIR>          jmods
22.08.2018  19:18    <DIR>          legal
12.11.2019  19:24    <DIR>          lib
12.11.2019  19:23             1.238 release

/bin, Windows :

Directory C:\dev\jdk-11\bin
...
12.11.2019  19:23           272.736 java.exe
...
12.11.2019  19:23            20.832 javac.exe
...

, , /bin PATH, java .

, , , Oracle AdoptOpenJDK, PATH .

, Java, java -version. , , !

openjdk version "11" 2018-09-25
OpenJDK Runtime Environment 18.9 (build 11+28)
OpenJDK 64-Bit Server VM 18.9 (build 11+28, mixed mode)

: .zip Java? .

Java

, Java (: JDK), , « ». .

OpenJDK

Java (: JRE / JDK) — OpenJDK.

, (: .zip java ). , , , MarcoJDK, . , Java SE.

, , (. TCK) .

, , String Java, (ay!) (, CLI), . Java.

OpenJDK ( Oracle) OracleJDK

, Java , — Oracle. Java, .

1. OpenJDK Oracle (!). , Oracle , , Java 14, Java 15.
2. OracleJDK — , 2019 . , , Oracle, . , , , JVM .

( Java 8) OpenJDK OracleJDK, , OracleJDK «». , .

, ( ) Java.

AdoptOpenJDK

2017 , Java User Group (Amazon, Microsoft, Pivotal, Red Hat ) AdoptOpenJDK.

OpenJDK / Java: HotSpot OpenJ9.

, Java.

Azul Zulu, Amazon Corretto, SAPMachine

OpenJDK OpenJDK Wikipedia. Azul Zulu, Amazon Corretto, SapMachine . , , / .

, .

OpenJDK

(Rafael Winterhalter) OpenJDK, : , , , .

: https://rafael.codes/openjdk/.

, 2019 , , jdk.zip (.tar.gz/.msi/.pkg) https://adoptopenjdk.net , .

Java 8-14

: ( ) Java 8 Java 14. Java .

, , Java 8 Java, (Java 9-14) .

, :

— Java 8 -

Java 8 , - Oracle. :

: ..

Java 8 , , , Runnable, , , :

 Runnable runnable = new Runnable(){
       @Override
       public void run(){
         System.out.println("Hello world !");
       }
     };

:

Runnable runnable = () -> System.out.println("Hello world two!");

, , .

Java 8 , Stream API. :

List<String> list = Arrays.asList("franz", "ferdinand", "fiel", "vom", "pferd");

Java 8, for, - .

API Streams :

list.stream()
    .filter(name -> name.startsWith("f"))
    .map(String::toUpperCase)
    .sorted()
    .forEach(System.out::println);

Java 8

, Stream, Lambda Optional Java 8. , — — Java 8.

— Java 9 -

Java 9 , :

, .

List<String> list = List.of("one", "two", "three");
Set<String> set = Set.of("one", "two", "three");
Map<String, String> map = Map.of("foo", "one", "bar", "two");

Streams

, takeWhile, dropWhile iterate.

Stream<String> stream = Stream.iterate("", s -> s + "s")
  .takeWhile(s -> s.length() < 10);

Optionals

Optionals ifPresentOrElse, .

user.ifPresentOrElse(this::displayAccount, this::displayLogin);

private :

public interface MyInterface {
    private static void myPrivateMethod(){
        System.out.println("Yay, I am private!");
    }
}

, try-with-resources diamond .

JShell

, Java , .

% jshell
|  Welcome to JShell -- Version 9
|  For an introduction type: /help intro
jshell> int x = 10
x ==> 10

HTTPClient

Java 9 HttpClient. Http Java , , Apache HttpClient OkHttp (, ).

Java 9 Java — , , Java.

Jigsaw: Java Jar

Java 9 Jigsaw Module System, - OSGI. Jigsaw — , .

Multi-Release .jar .jar, JVM. , - / , Java 8 Java 10, .

— Java 10 -

Java 10 , .. , , , , , — var, .

: var

// Pre-Java 10
String myName = "Marco";
// With Java 10
var myName = "Marco"

Javascript-, ? Java var (, dpash, , ).

— Java 11 -

Java 11 .

( ):

"Marco".isBlank();
"Mar\nco".lines();
"Marco  ".strip();
Path path = Files.writeString(Files.createTempFile("helloworld", ".txt"), "Hi, my name is!");
String s = Files.readString(path);

Java 10, Java . .

ubuntu@DESKTOP-168M0IF:~$ java MyScript.java

(var) -

:

(var firstName, var lastName) -> firstName + lastName

HttpClient

HttpClient Java 9, , .

Flight Recorder ( ), No-Op, Nashorn-Javascript-Engine deprecated () ..

— Java 12 -

Java 12 , Unicode 11 switch, .

— Java 13 -

, , , Unicode 12.1, ( ):

Switch (Preview — )

Switch . - , :

switch :

switch(status) {
  case SUBSCRIBER:
    // code block
    break;
  case FREE_TRIAL:
    // code block
    break;
  default:
    // code block
}

Java 13 switch :

boolean result = switch (status) {
    case SUBSCRIBER -> true;
    case FREE_TRIAL -> false;
    default -> throw new IllegalArgumentException("something is murky!");
};

()

- Java:

String htmlBeforeJava13 = "<html>\n" +
              "    <body>\n" +
              "        <p>Hello, world</p>\n" +
              "    </body>\n" +
              "</html>\n";
String htmlWithJava13 = """
              <html>
                  <body>
                      <p>Hello, world</p>
                  </body>
              </html>
              """;

Java 14

Switch ()

Switch , 12 13, .

int numLetters = switch (day) {
    case MONDAY, FRIDAY, SUNDAY -> 6;
    case TUESDAY                -> 7;
    default      -> {
      String s = day.toString();
      int result = s.length();
      yield result;
    }
};

Records ()

Records (), Java. Java 14, , () / , equals / hashcode, toString.

final class Point {
    public final int x;
    public final int y;

    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }
}
    // state-based implementations of equals, hashCode, toString
    // nothing else

:

record Point(int x, int y) { }

, .

NullPointerException

, NullPointerExceptions , null.

author.age = 35;
---
Exception in thread "main" java.lang.NullPointerException:
     Cannot assign field "age" because "author" is null

InstanceOf ()

(cast) instanceof, :

if (obj instanceof String) {
    String s = (String) obj;
    // use s
}

, , cast.

if (obj instanceof String s) {
    System.out.println(s.contains("hello"));
}

()

jpackage (), Java- , .

• Linux: deb rpm
• macOS: pkg dmg
• Windows: MSI EXE

Concurrent Mark Sweep (CMS) , Z.

Java 15

, . !

:

• Wie man Java installiert, welche Version man bekommt und wo man es bekommt (Hinweis: AdoptOpenJDK ).
• Was ist eine Java-Distribution, was gibt es und was sind die Unterschiede?
• Was sind die Unterschiede zwischen bestimmten Versionen von Java.

Feedback, Korrekturen und Ihre Eingabe sind immer willkommen! Hinterlasse einfach einen Kommentar unten.

Danke fürs Lesen!

Danksagung

Stephen Coleburn hat einen fantastischen Artikel über die verschiedenen verfügbaren Java-Distributionen geschrieben. Danke Steven!