Java 9 - 16

# Java 9 - 16
## What happened the last 7 years
### Matthias

----
## Disclaimer
* Part I (tried to focus on language Features & API)
  * maybe following parts with
    * java "internal" changes (e.g. Garbage Collector, Performance, tooling)
    * deprecations
* no guarantee on completeness

----
## Sources
* [OpenJDK](https://openjdk.java.net/jeps/0)
* [Marcobehler.com](https://www.marcobehler.com/guides/a-guide-to-java-versions-and-features#_why_are_companies_still_stuck_with_java_8)
* [.Lost in Coding](https://ondro.inginea.eu/index.php/new-features-in-java-versions-since-java-8/)
* [Advanced Web Machinery](https://advancedweb.hu/a-categorized-list-of-all-java-and-jvm-features-since-jdk-8-to-16/#new-apis)

----
## Java history

----
## Why Java 8
* rich feature set
  * Stream API (Collections)
  * Lambda Functions & Functional Interfaces
  * Optionals
  * New Date Time API
* changed licensing which lead to confusion (Java Distributions)
* initial problems with commonly used build tools
* is a LTS version

---
# Java 9

> [OpenJDK 9](https://openjdk.java.net/projects/jdk9/)

----
## Collection factory methods

```Java
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```](https://docs.oracle.com/javase/8/docs/api/java/util/stream/Stream.html#iterate-T-java.util.function.UnaryOperator-) with condition

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

## Optionals: ifPresentOrElse()

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

----
## JShell (Java Playground)
```
% jshell
|  Welcome to JShell -- Version 16.0.1
|  For an introduction type: /help intro

jshell> int x = 10
x ==> 10

jshell> System.out.println(x > 5 ? "big number" : "small number")
big number
```

### Exit with

```
jshell> /exit
|  Goodbye
```

(You are welcome ;-) )

----
## misc
* [TLS1.3 Support](https://openjdk.java.net/jeps/332)
* [Java Platform module System](https://openjdk.java.net/jeps/332)
* Flow API (reactive Streams)
* [MultiResolutionImage](https://docs.oracle.com/javase/9/docs/api/java/awt/image/MultiResolutionImage.html)
* [Class.getPackageName()](https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/lang/Class.html#getPackageName())

---
# Java 10

> [OpenJDK 10](https://openjdk.java.net/projects/jdk/10/)

----
## Local-variable type Inference: ```var```-keyword

```Java
// Pre-Java 10
String myName = "Volker";

// With Java 10
var myName = "Volker"
```

---
# Java 11

> [OpenJDK 11](https://openjdk.java.net/projects/jdk/11/)

----
## new methods on ```String```

* ```repeat()```, ```isBlank()```, ```strip()```, ```lines()```

```Java
"".isBlank();                           // -> true
"Each\nline\ncounts".lines().toList();  // -> Stream of lines
"   we messed ist up  ".strip();        // -> "we messed it up"
"Hello".repeat(3)                       // -> "HelloHelloHello"
```

## ```var``` supported by lambda parameters

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

----
## HTTPClient (Preview >= 9)

<div>
```Java
import java.io.IOException;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.URI;
import java.net.http.HttpResponse;

public class HttpClientExample {

public static void main(String[] args) throws IOException, InterruptedException {
        HttpClient httpClient = HttpClient.newBuilder().build();

HttpRequest request =
                HttpRequest.newBuilder()
                        .uri(URI.create("https://www.google.com/"))
                        .GET()
                        .build();

HttpResponse<String> response =
                httpClient.send(request, HttpResponse.BodyHandlers.ofString());

System.out.println(response.statusCode());
        System.out.println(response.body());
    }
}
```
</div>

---
# Java 12

> [OpenJDK 12](https://openjdk.java.net/projects/jdk/12/)

----
## new methods on ```String```

* ```indent()```, ```transform()```

## [CompactNumberFormat class](https://docs.oracle.com/en/java/javase/12/docs/api/java.base/java/text/CompactNumberFormat.html)

* formating numbers for a Local
  * US: 1000 -> 1K, 1000000 -> 1M
  * IN: 1000 -> 1 हज़ार, 50000000 -> 5 क
  * DE: 1000 -> 1.000, 1000000 -> 1 Mio

## Unicode 11 support

---
# Java 13

> [OpenJDK 13](https://openjdk.java.net/projects/jdk/13/)

## Unicode 12.1 support

---
# Java 14

> [OpenJDK 14](https://openjdk.java.net/projects/jdk/14/)

----
## Switch Expression (Preview: 12, 13)

* new (including new ```yield``` keyword)
  * no fall-through
  * single statement and code block
  * supporting value return (with yield)

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

---
# Java 15

> [OpenJDK 15](https://openjdk.java.net/projects/jdk/15/)

----
## Helpfull NullPointerException message

<div>
```Java
public class NullPointerExample {

public static void main(String[] args) {

System.out.println("NullPointer Exception message:");

MyClass myClass = null;
        try {
            System.out.println(myClass.myName.length());
        }catch (Exception e){
            e.printStackTrace();
        }

myClass = new MyClass();
        try {
            System.out.println(myClass.myName.length());
        }catch (Exception e){
            e.printStackTrace();
        }
    }

private static class MyClass{
        protected String myName;
        protected MyClass meAgain;
    }
}
```
</div>

* old
<div>
```
NullPointer Exception message:
java.lang.NullPointerException: null
	at de.mubn.java15.NullPointerExample.main(NullPointerExample.java:11)
java.lang.NullPointerException: null
  	at de.mubn.java15.NullPointerExample.main(NullPointerExample.java:20)
```
</div>

* new
<div>
```
NullPointer Exception message:
java.lang.NullPointerException: Cannot read field "myName" because "myClass" is null
	at de.mubn.java15.NullPointerExample.main(NullPointerExample.java:11)
java.lang.NullPointerException: Cannot invoke "String.length()" because "myClass.myName" is null
  	at de.mubn.java15.NullPointerExample.main(NullPointerExample.java:20)
```
</div>

----
## Text Blocks (Preview: 13, 14)

* old

<div>
```Java
String html = "<html>\n" +
              " <body>\n" +
              "   <p>Hello, world</p>\n" +
              " </body>\n" +
              "</html>";
```
</div>

* new

<div>
```Java
String html = """
            <html>
              <body>
                <p>Hello, world</p>
              </body>
            </html>
            """;
```
</div>

---
# Java 16

> [OpenJDK 16](https://openjdk.java.net/projects/jdk/16/)

----
## Pattern Matching for instanceof

```Java
if (x instanceOf String s) {
  String a = s;
}
```

## Record Type

* immutable data Class
* implicit methods -> avoiding boiler plate code
  * getters, constructor, equals, hashCode, toString

```Java
record Point(int x, int y){ }

Point myPoint = new Point(10, 15);

myPoint.x();                  // -> 10
System.out.println(myPoint);  // -> "Point[x=10, y=15]"

```

----
## Sealed Classes (still PREVIEW)

```Java
public abstract sealed class Shape permits Circle, Rectangle, Square {
  // ...
}
```