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What is new in Java 14

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Java 14 reached General Availability on 17 March 2020, download Java 14 here.

Java 14 features.

Java 14 developer features.

Switch expression (standard), records (preview), pattern matching (preview), text blocks or multi-lines (second preview), foreign-memory access APIs (incubator)

1. JEP 305: Pattern Matching for instanceof (Preview)

Before Java 14, we use instanceof-and-cast to check the object’s type and cast to a variable.


  if (obj instanceof String) {        // instanceof
    String s = (String) obj;          // cast
    if("jdk14".equalsIgnoreCase(s)){
        //...
    }
  }else {
	   System.out.println("not a string");
  }

Now Java 14, we can refactor above code like this:


  if (obj instanceof String s) {      // instanceof, cast and bind variable in one line.
      if("jdk4".equalsIgnoreCase(s)){
          //...
      }
  }else {
	   System.out.println("not a string");
  }

if obj is an instance of String, then it is cast to String and assigned to the binding variable s.

History
This pattern matching is a standard feature in Java 16, JEP 394.

Further Reading

2. JEP 343: Packaging Tool (Incubator)

New jpackage tool to package a Java application into a platform-specific package like:

  • Linux: deb and rpm
  • macOS: pkg and dmg
  • Windows: msi and exe

P.S This packaging tool is a standard feature in Java 16, visit this jpackage example.

Further Reading

3. JEP 345: NUMA-Aware Memory Allocation for G1

New NUMA-aware memory allocation mode, improves the G1 performance on large machines. Add +XX:+UseNUMA option to enable it.

Further Reading

4. JEP 349: JFR Event Streaming

Improved the existing JFR to support event streaming, it means now we can stream the JFR events in real-time, without the need to dump the recorded events to disk and parse it manually.

The JDK Flight Recorder (JFR) is a tool for collecting diagnostic and profiling data about a running Java application. Normally, we start a recording, stop it, dump the recorded events to disk for parsing, it works well for profiling, analysis, or debugging.

Further Reading

5. JEP 352: Non-Volatile Mapped Byte Buffers

Improved FileChannel API to create MappedByteBuffer that access to non-volatile memory (NVM) – a memory that can retrieve stored data even after having been power cycled. For example, this feature ensures that any changes which might still be in the cache are written back to memory.

P.S Only Linux/x64 and Linux/AArch64 OS support this!

Further Reading

6. JEP 358: Helpful NullPointerExceptions

Improved the description of NullPointerExceptions by telling which variable was null. Add -XX:+ShowCodeDetailsInExceptionMessages option to enable this feature.

A simple Java file that throws an NullPointerException.

Test.java

import java.util.Locale;

public class Test {

    public static void main(String[] args) {

        String input = null;
        String result = showUpperCase(input); // NullPointerException
        System.out.println(result);

    }

    public static String showUpperCase(String str){
        return str.toUpperCase(Locale.US);
    }

}

Before Java 14.


$ /usr/lib/jvm/jdk-14/bin/java Test

Exception in thread "main" java.lang.NullPointerException
	at Test.showUpperCase(Test.java:15)
	at Test.main(Test.java:9)

Java 14 with -XX:+ShowCodeDetailsInExceptionMessages option.


$ /usr/lib/jvm/jdk-14/bin/java -XX:+ShowCodeDetailsInExceptionMessages Test

Exception in thread "main" java.lang.NullPointerException:
  Cannot invoke "String.toUpperCase(java.util.Locale)" because "<parameter1>" is null
	at Test.showUpperCase(Test.java:15)
	at Test.main(Test.java:9)

Further Reading

7. JEP 359: Records (Preview)

A new class called record (aka data class), it is a final class, not abstract, and all of its fields are final as well. The record will automatically generate the tedious constructors, public get, equals(), hashCode(), toString() during compile time.

P.S No setters, all fields are final.

A record or data class, create the class name and variables, and we can start using it.

Point.java

record Point(int x, int y) { }
Test.java

public class Test {

    public static void main(String[] args) {

        Point p1 = new Point(10, 20);      
        System.out.println(p1.x());         // 10
        System.out.println(p1.y());         // 20

        Point p2 = new Point(11, 22);
        System.out.println(p2.x());         // 11
        System.out.println(p2.y());         // 22

	      Point p3 = new Point(10, 20);     
        System.out.println(p3.x());         // 10
        System.out.println(p3.y());         // 20

        System.out.println(p1.hashCode());  // 330
        System.out.println(p2.hashCode());  // 363
        System.out.println(p3.hashCode());  // 330

        System.out.println(p1.equals(p2));  // false
        System.out.println(p1.equals(p3));  // true
        System.out.println(p2.equals(p3));  // false

    }

}

Test it with --enable-preview.


$ /usr/lib/jvm/jdk-14/bin/javac --enable-preview --release 14 Point.java
$ /usr/lib/jvm/jdk-14/bin/javac --enable-preview --release 14 Test.java

$ /usr/lib/jvm/jdk-14/bin/java --enable-preview Test

Output


10
20
11
22
10
20
330
363
330
false
true
false

History

  • Java 15 JEP 384 has the second preview of records, with new features like sealed types, local records, annotation on records, and Reflection APIs.
  • Java 16 JEP 395, record or data class is the standard feature.

Further Reading

8. JEP 361: Switch Expressions (Standard)

The switch expression was a preview feature in Java 12 and Java 13; now it is officially JDK standard feature, it means from Java 14 and onward, we can return value via switch expressions without specifying the --enable-preview option.

See a recap; we can use yield to return a value from a switch.


	private static int getValueViaYield(String mode) {
        int result = switch (mode) {
            case "a", "b":
                yield 1;
            case "c":
                yield 2;
            case "d", "e", "f":
								// do something here...
							 	System.out.println("Supports multi line block!");
                yield 3;
            default:
                yield -1;
        };
        return result;
    }

Or via a label rules or arrows.


	private static int getValueViaArrow(String mode) {
        int result = switch (mode) {
            case "a", "b" -> 1;
            case "c" -> 2;
            case "d", "e", "f" -> {
                // do something here...
                System.out.println("Supports multi line block!");
                yield 3;
            }
            default -> -1;
        };
        return result;
    }

Further Reading

9. JEP 362: Deprecate the Solaris and SPARC Ports

Dropping support for Solaris/SPARC, Solaris/x64, and Linux/SPARC ports, fewer platforms support means faster delivery for new features.

P.S Java 15 JEP 381 removed the above ports.

Further Reading

10. JEP 363: Remove the Concurrent Mark Sweep (CMS) Garbage Collector

Java 9 JEP 291 deprecated this Concurrent Mark Sweep (CMS) Garbage Collector, and now it is officially removed.


/usr/lib/jvm/jdk-14/bin/java -XX:+UseConcMarkSweepGC Test

OpenJDK 64-Bit Server VM warning: Ignoring option UseConcMarkSweepGC; support was removed in 14.0

Further Reading

11. JEP 364: ZGC on macOS (Experimental)

Java 11 JEP 333 introduced the Z Garbage Collector (ZGC) on Linux, and now it ports to macOS.

P.S This ZGC is a product feature in Java 15 JEP 377.

Further Reading

12. JEP 365: ZGC on Windows (Experimental)

Java 11 JEP 333 introduced the Z Garbage Collector (ZGC) on Linux, and now it ports to Windows version >= 1803.

P.S This ZGC is a product feature in Java 15 JEP 377.

Further Reading

13. JEP 366: Deprecate the ParallelScavenge + SerialOld GC Combination

Due to less use and high maintenance effort, Java 14 deprecates the combination of the parallel young generation and serial old generation GC algorithms.


/usr/lib/jvm/jdk-14/bin/java -XX:-UseParallelOldGC Test

OpenJDK 64-Bit Server VM warning: Option UseParallelOldGC was deprecated in version 14.0 and will likely be removed in a future release.

Further Reading

14. JEP 367: Remove the Pack200 Tools and API

Java 11 JEP 336 deprecated the pack200 and unpack200 tools, and the Pack200 API in the java.util.jar package, and now it is officially removed.

Further Reading

15. JEP 368: Text Blocks (Second Preview)

The first preview appeared in Java 13 JEP 354, now added two more new escape sequences:

  • \<end-of-line> suppresses the line termination.
  • \s is translated into a single space.
Test.java

public class Test {

    public static void main(String[] args) {

        String html = "<html>\n" +
                      "   <body>\n" +
                      "      <p>Hello, World</p>\n" +
                      "   </body>\n" +
                      "</html>\n";

        String java13 = """
                        <html>
                            <body>
                                <p>Hello, World</p>
                            </body>
                        </html>
                        """;

        String java14 = """
                        <html>
                            <body>\
                                <p>Hello, '\s' World</p>\
                            </body>
                        </html>
                        """;

        System.out.println(html);
        System.out.println(java13);
        System.out.println(java14);

    }

}


$ /usr/lib/jvm/jdk-14/bin/javac --enable-preview --release 14 Test.java
$ /usr/lib/jvm/jdk-14/bin/java --enable-preview Test

Output


html>
   <body>
      <p>Hello, World</p>
   </body>
</html>

<html>
    <body>
        <p>Hello, World</p>
    </body>
</html>

<html>
    <body>        <p>Hello, ' ' World</p>    </body>
</html>

P.S This text blocks is a permanent feature in Java 15.

Further Reading

16. JEP 370: Foreign-Memory Access API (Incubator)

An incubator module, allow Java API to access foreign memory outside of the Java heap.

Test.java

import jdk.incubator.foreign.*;
import java.lang.invoke.VarHandle;
import java.nio.ByteOrder;

public class Test {

    public static void main(String[] args) {

	     VarHandle intHandle = MemoryHandles.varHandle(
            int.class, ByteOrder.nativeOrder());

        try (MemorySegment segment = MemorySegment.allocateNative(1024)) {

            MemoryAddress base = segment.baseAddress();

            // print memory address
            System.out.println(base);                 

            // set value 999 into the foreign memory
	          intHandle.set(base, 999);                 

            // get the value from foreign memory
            System.out.println(intHandle.get(base));  

        }

    }

}

Compile and run with incubator module jdk.incubator.foreign.


$ /usr/lib/jvm/jdk-14/bin/javac --add-modules jdk.incubator.foreign Test.java

warning: using incubating module(s): jdk.incubator.foreign
1 warning

$ /usr/lib/jvm/jdk-14/bin/java --add-modules jdk.incubator.foreign Test

WARNING: Using incubator modules: jdk.incubator.foreign
MemoryAddress{ region: MemorySegment{ id=0x4aac6dca limit: 1024 } offset=0x0 }
999

History

  • Java 15 JEP 383 has the second Incubator.
  • Java 16 JEP 393 has the third Incubator.

Further Reading

Download Source Code

$ git clone https://github.com/mkyong/core-java

$ cd java-14

References

About Author

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Founder of Mkyong.com, love Java and open source stuff. Follow him on Twitter. If you like my tutorials, consider make a donation to these charities.

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Cristobal
4 years ago

Hi mkyong. Please check your Test.java example. I think this line of code: System.out.println(p1.equals(p3)); // Point[x=10, y=20] should be System.out.println(p1); Best regards

2
Reply
mkyong
3 years ago
Reply to  Cristobal

Thanks, article is update.

1
Reply
Michel ten Voorde
3 years ago

There’s something wrong with the paragraph numbering, there are two paragraphs 3.

1
Reply
Viktor
3 years ago

Thank you for human readable format of new java features.

Add a donate button somewhere.

0
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Shubham
3 years ago

In para 14 example, Following worked for me.
String java14 = “””

Hello,\sWorld
\

“””;

0
Reply