Java 15 and 16 Features
✅ Java 15 Features (Released: Sept 2020)
1. 🔹 Text Blocks (Standard – JEP 378)
Final version of multi-line string literals introduced as preview in Java 13/14.
Example:
String html = """
<html>
<body>Hello, Java 15!</body>
</html>
""";
2. 🔹 Sealed Classes (Preview – JEP 360)
Restricts which classes can extend or implement a class/interface.
Example:
public sealed class Shape permits Circle, Square {}
final class Circle extends Shape {}
final class Square extends Shape {}
✅ Useful for better control in inheritance and modeling domain logic.
3. 🔹 Hidden Classes (JEP 371)
Classes intended for framework use only, not discoverable via reflection.
Example use case: proxies or dynamically generated code (e.g., in frameworks like Spring, Hibernate).
4. 🔹 Records (2nd Preview – JEP 384)
Continued preview of record types, compact syntax for data-holding classes.
5. 🔹 Pattern Matching for instanceof (2nd Preview – JEP 375)
Further refinement of instanceof pattern matching from Java 14.
6. 🔹 ZGC Improvements (JEP 377)
-
ZGC becomes a production feature (low-latency GC)
-
Now supports heap sizes from a few MBs to multiple TBs
7. 🔹 Removal of Nashorn JavaScript Engine (JEP 372)
The Nashorn engine was deprecated in Java 11 and fully removed in Java 15.
✅ Java 16 Features (Released: March 2021)
1. 🔹 Records (Standard – JEP 395)
Records became a final feature!
Example:
public record Person(String name, int age) {}
Person p = new Person("Alice", 30);
System.out.println(p.name()); // Alice
✅ Great for DTOs and immutable objects with less boilerplate.
2. 🔹 Pattern Matching for instanceof (Standard – JEP 394)
Now a final feature!
Example:
if (obj instanceof String s) {
System.out.println(s.toUpperCase());
}
✅ Cleaner and safer casting.
3. 🔹 Sealed Classes (2nd Preview – JEP 397)
Improved from Java 15 preview.
4. 🔹 JEP 376 – JDK Internal APIs Encapsulation (Strong Encapsulation)
Further encapsulates internal JDK APIs — breaks reflection-based access unless explicitly opened.
✅ Improves modularity and security.
5. 🔹 JEP 338 – Unix-Domain Socket Channels
Java can now communicate using Unix domain sockets (used in inter-process communication).
Example:
UnixDomainSocketAddress address = UnixDomainSocketAddress.of("/tmp/mysocket");
SocketChannel socketChannel = SocketChannel.open(StandardProtocolFamily.UNIX);
6. 🔹 Foreign Linker API (Incubator – JEP 389)
Allows calling native code (like C functions) from Java in a safer and more portable way.
7. 🔹 Packaging Tool (JEP 392)
A cross-platform tool to create native installers (.msi, .pkg, .deb, etc.)
Command:
jpackage --input out/ --name MyApp --main-jar myapp.jar --type exe
✅ Useful for desktop application deployment.
🔚 Summary Comparison Table
| Feature | Java 15 | Java 16 |
|---|---|---|
| Text Blocks | ✅ Final | ✅ |
| Records | 🧪 Preview 2 | ✅ Final |
Pattern Matching (instanceof) |
🧪 Preview 2 | ✅ Final |
| Sealed Classes | 🧪 Preview | 🧪 Preview 2 |
| Hidden Classes | ✅ | — |
| ZGC Enhancements | ✅ | — |
| Packaging Tool | — | ✅ |
| Unix-Domain Sockets | — | ✅ |
| Foreign Linker API | — | 🧪 Incubator |
| JDK Internals Encapsulation | — | ✅ Stronger enforcement |