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Java 18 Features With Examples

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Java Duke surfing

Since version 9, Java has new features every 6 months and it's very hard to keep track of these new changes. Most of the information on the internet describes changes between the last 2 Java versions. However, if you're in a similar situation as me, you're not using one of the latest Java versions but a version several releases older.

Then it's useful to know which new features were added since the version you use now, or between the versions that you use now and the one you want to start using next. Therefore I've compiled a table with all new features added since Java 8 for each new Java version.

Below you can find tables for:

  • New Java language features – additions to the Java language or APIs
  • New tools and features in OpenJDK – additions outside of the language, such as command line tools or JVM improvements
  • Deprecated/removed features and APIs

Note that I didn't include all the new features and API additions, only those that are useful for most developers, to keep the list brief.

This article isn't about choosing the right Java version for you to use. But I'll at least summarize all the Java versions since Java 8 and for your convenience:

  • Java 8 – LTS release (Long Term Support), last LTS release before JPMS (modules) were introduced in Java 9
  • Java 11 – LTS release
  • Java 17 – LTS release, the latest LTS release until March 2023
  • Java 18 – non-LTS release, the latest version in March 2022
  • all other Java versions – non-LTS releases

In most cases, you should only use LTS releases in production. That is unless you have specific needs to use the greatest and latest and are willing to upgrade to a new Java version every 6 months. To find out more about Java LTS releases, you can read The art of long-term support and what LTS means for the Java ecosystem by Oracle.

New Java language features since Java 8

Feature

Since

Preview since

Simple Web Server (a.k.a com.sun.net.httpserver.SimpleFileServer)

Java API: SimpleFileServer.createFileServer(new InetSocketAddress(9000), path, logLevel).start();

Cmd Line: jwebserver -p 9000

18

Code Snippets in Java API Documentation
{@snippet : lines of code} instead of <pre>{@code lines of code }</pre>

18

UTF-8 by Default – instead of the charset defined by the system.
Run javac -encoding UTF-8 with JDK 8-17 to check for Java source encoding issues.

18

Context-Specific Deserialization Filters – allow applications to configure deserialization filters, either specify a pattern via a system property, or a filter factory via a system property or via ObjectInputFilter.Config

17

Pattern Matching for switch – like instanceof for switch; switch is an expression and can be assigned
String result = switch (o) {
case null -> null;
case 0 -> throw new RuntimeException("Cannot be 0"); // Special cases
case Integer i && i > 0 -> "Positive number";
case Integer i -> "Negative number"; // 0 and positive numbers handled by above rules
case String s -> s;
case Point p -> p.toString();
case int[] ia -> "Array length" + ia.length;
default -> "Something else";
}

17

Foreign Function & Memory API (an alternative to JNI)

16

Vector API – express computations that compile to optimal hardware instructions

16

Sealed classes (inheritance only for allowed classes):
public abstract sealed class Shape permits Circle, Rectangle, Square {...}

17

15

Record type – data classes with implicit getters, constructor, equals, hashCode and toString methods:
record Point(int x, int y) { }

16

14

Static members in inner classes (part of Record type JEP)
new Object() {
static record MyData(String data) {};
public static final int CONSTANT = 1;
};

16

16

Pattern Matching for instanceof:
if (x instanceOf String s) { String a = s; }

16

14

Text blocks:
String query = """
SELECT "EMP_ID", "LAST_NAME"
FROM "EMPLOYEE_TB";
"""

15

13

New String methods (formatted, stripIndent, translateEscapes)

15

Switch expressions:
boolean isWeekend = switch (day) {
case SATURDAY, SUNDAY -> true;
default -> false;
};

14

12

New String methods (indent, transform)

12

CompactNumberFormat class

12

New String methods (repeat, isBlank, strip, lines)

11

var type allowed in Lambda Parameters:
(@NonNull var x) -> process(x)

11

New HTTP client API

11

9

TLS v1.3 – support for a new SSL/TLS protocol version

11

var type allowed for local variables:
var length = str.length();

10

Flow API (reactive streams)

9

Java Platform Module System (modules)

9

Collection factory methods:
List.of(a, b, c); Set.of(d, e, f, g); Map.of(k1, v1, k2, v2);

9

Stream API improvements (takeWhile, dropWhile, ofNullable, iterate with condition)

9

Multi-Resolution Image API

9

Stack-Walking API

9

this.getClass().getPackageName()

9

Process API updates (detailed info about processes, e.g. ID, onExit, destroy)

9

new methods in CompletableFuture API (delay, timeout)

9

Interface private methods

9

since and forRemoval in @Deprecated

9

Interface Default and Static Methods

8

Method References

8

Optional class

8

Lambda expressions

8

Functional interfaces

8

Stream API

8

Effectively Final Variables

8

Repeating Annotations

8

New Date Time API

8

Tool / feature

Since

Experimental since

Packaging Tool

14

Epsilon (no-op) GC

11

Experimental Java-Based JIT Compiler (Graal VM)

10

Shenandoah GC

15

12

Z GC (JEP 377)

15

11

Helpful NullPointerExceptions

14

Launching Java files as scripts

11

Flight recorder (data collection framework for troubleshooting)

11

Docker Container Support:
-XX:-UseContainerSupport

10,
8u191

Flexible heap size selection:
-XX:MaxRAMPercentage

10,
8u191

Application Class-Data Sharing (CDS)

10

jlink – custom JRE image, subset of JRE

9

JShell (Java REPL) – run Java commands interactively

9

Multi-Release JAR Files

9

Compact Strings

9

Deprecated/removed features and APIs:

Feature / API

Deprecated since

Removed since

Deprecate Finalization for Removal (finalize() and similar methods)

18

Deprecate the Security Manager for Removal

17

Deprecate the Applet API for Removal

17

Constructors of primitive wrapper classes (e.g. new Integer(1))

16

RMI Activation

15

17

ParallelScavenge + SerialOld GC Combination

14

Strongly Encapsulate JDK Internals (except sun.misc.Unsafe and some more)
– internal JDK classes won't be available anymore

9

17

Nashorn JavaScript Engine

11

15

Solaris and SPARC Ports

14

15

CMS GC

9

14

Pack200 Tools and API

11

14

Java FX (moved to OpenJFX)

11

Java EE and CORBA modules (JAX-WS, JAXB, JAF, Common Annotations, CORBA, JTA)
Look here to find replacements for the removed modules

9

11

javah Native-Header Generator

10

Applet API (Deprecated For Removal in Java 17)

9

jhat Heap Visualizer

9

Launch-Time JRE Version Selection

9

rt.jar and tools.jar

9

The extension mechanism (java.ext.dirs property)

9

Rarely-Used GC Combinations

8

9

For more details, the javaalmanac.io/ catalog is very useful to browse the changes in Java thoughout all its history. It can give you complete diff of APIs between selected Java versions, e.g. between Java 8 and Java 11. Very useful If you're thinking about migrating to a specific Java version.

Dávid Csákvári also wrote a similar article as mine for new features between Java 8 and Java 17, which is more detailed and with a lot of useful examples.

If you want to get started with Java 17 quickly and try out all the new features, here's a nice article to follow to get you started fast: Java 17 New Features Tutorial.

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Source: https://ondro.inginea.eu/index.php/new-features-in-java-versions-since-java-8/

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