JDK 16 · JSR 391

Java 16

JDK 16 is Java SE 16, JSR 391, generally available on 16 March 2021. Records and pattern matching for instanceof become permanent. Sealed classes are still a preview. jpackage leaves the incubator. Stream.toList() arrives in this release.

How to read the status

Final. The change shipped in this release as a permanent part of that release.
Preview. It can be tried with --enable-preview. A preview is not a permanent language or API guarantee.
Incubator. An incubator API is not a supported standard API. It can change or be removed.

Status

Language

Records

JEP 395 · Final · Language

A record declares a final carrier with a canonical constructor, accessors, and value-based equals, hashCode, and toString.

Preview in Java 14 (JEP 359) and Java 15 (JEP 384).

OpenJDK JEP 395 (leaves JavaMastery)

Related reading: Records and sealed classes

Curriculum file: versions5Java17Features.java

Pattern Matching for instanceof

JEP 394 · Final · Language

instanceof can test a type and bind a pattern variable in the same expression.

Preview in Java 14 (JEP 305) and Java 15 (JEP 375).

OpenJDK JEP 394 (leaves JavaMastery)

Curriculum file: versions5Java17Features.java

Sealed Classes (Second Preview)

JEP 397 · Preview · Language

Sealed classes are previewed again. They are not final.

First preview in Java 15 (JEP 360). Final in Java 17 (JEP 409).

OpenJDK JEP 397 (leaves JavaMastery)

Related reading: Records and sealed classes

APIs / Libraries

Stream.toList()

Final · APIs / Libraries

Stream gains toList(), which returns an unmodifiable list. The Java 9–11 example does not call it. It keeps Collectors.toList() so that file can stay a Java 11 program.

Vector API (Incubator)

JEP 338 · Incubator · APIs / Libraries

An incubator API for vector computations. It is not a standard API.

It is still incubating in Java 25, as the tenth incubator (JEP 508).

OpenJDK JEP 338 (leaves JavaMastery)

Unix-Domain Socket Channels

JEP 380 · Final · APIs / Libraries

SocketChannel and ServerSocketChannel can use Unix-domain sockets.

OpenJDK JEP 380 (leaves JavaMastery)

JVM / Runtime

Strongly Encapsulate JDK Internals by Default

JEP 396 · Final · JVM / Runtime

JDK-internal APIs are strongly encapsulated by default. The choice can still be relaxed. Java 17 removes that relaxation for most internals.

OpenJDK JEP 396 (leaves JavaMastery)

Tools / Platform

Packaging Tool

JEP 392 · Final · Tools / Platform

jpackage is a supported tool for producing platform packages.

Incubated in Java 14 (JEP 343).

OpenJDK JEP 392 (leaves JavaMastery)

Examples

versions5Java17Features.javaCumulative Java 12–17 example · Requires Java 17Final forms only: switch expressions from Java 14, text blocks from Java 15, records and instanceof patterns from Java 16, and sealed classes from Java 17. This is not a Java 12 preview program. Pattern matching for switch was still a preview in Java 17 and is not used.

Historical notes

The cumulative example’s records and instanceof patterns match this release. Its sealed classes match the Java 17 final form, so the file is not a Java 16 program.

Sources. General availability and the JEP list: OpenJDK JDK 16. JSR 391: Oracle Java SE specifications. OpenJDK JDK 16 (leaves JavaMastery)

All versions