Text Blocks
Text blocks are a permanent multi-line string literal.
Preview in Java 13 (JEP 355) and Java 14 (JEP 368).
OpenJDK JEP 378 (leaves JavaMastery)
Related reading: Strings
Curriculum file: versions5Java17Features.java
JDK 15 · JSR 390
Java 15
JDK 15 is Java SE 15, JSR 390, generally available on 15 September 2020. Text blocks become permanent. Sealed classes are a preview, and records and instanceof patterns are in a second preview. ZGC and Shenandoah leave experimental status.
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.
Language
Sealed Classes (Preview)
A sealed type lists the classes and interfaces that may extend or implement it. In Java 15 this is a preview.
Second preview in Java 16 (JEP 397). Final in Java 17 (JEP 409).
OpenJDK JEP 360 (leaves JavaMastery)
Related reading: Records and sealed classes
Records (Second Preview)
Records are previewed again. They are not yet a permanent class form.
First preview in Java 14 (JEP 359). Final in Java 16 (JEP 395).
OpenJDK JEP 384 (leaves JavaMastery)
Related reading: Records and sealed classes
Pattern Matching for instanceof (Second Preview)
instanceof patterns are previewed again, without becoming final.
First preview in Java 14 (JEP 305). Final in Java 16 (JEP 394).
APIs / Libraries
Edwards-Curve Digital Signature Algorithm (EdDSA)
The JDK implements EdDSA signatures, a cryptographic API addition.
JVM / Runtime
ZGC: A Scalable Low-Latency Garbage Collector
ZGC becomes a product feature. It is not the default collector.
Experimental in Java 11 (JEP 333).
OpenJDK JEP 377 (leaves JavaMastery)
Related reading: JVM and memory
Shenandoah: A Low-Pause-Time Garbage Collector
Shenandoah becomes a product feature. It is not the default collector.
Experimental in Java 12 (JEP 189).
OpenJDK JEP 379 (leaves JavaMastery)
Related reading: JVM and memory
Tools / Platform
Remove the Nashorn JavaScript Engine
Nashorn is removed.
It shipped in Java 8 and was deprecated in Java 11 (JEP 335).
Examples
- versions5Java17Features.javaFinal 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.
Related reading
Historical notes
Hidden classes (JEP 371) also ship. They are a JVM feature for frameworks that generate classes, not a new source construct for typical programs.
Sources. General availability and the JEP list: OpenJDK JDK 15. JSR 390: Oracle Java SE specifications. OpenJDK JDK 15 (leaves JavaMastery)