Java 17 Features

Clean, structured and easy-to-navigate Java reference

Category	Feature	Description	Status
Language	Sealed Classes	Restrict which classes can extend or implement a class/interface	Final
Language	Pattern Matching for instanceof	Simplifies type casting after instanceof check	Final
Language (Preview)	Pattern Matching for switch	Use patterns in switch statements	Preview
Language (Preview)	Record Patterns (early incubations toward deconstruction)	Destructure record components	Preview (early stage)
Core API	Enhanced Pseudo-Random Number Generators	New RandomGenerator interface & implementations	Final
Core API	New macOS Rendering Pipeline	Metal-based rendering for macOS	Final
Core API	Context-Specific Deserialization Filters	More control over object deserialization	Final
JVM	Strongly Encapsulate JDK Internals	Internal APIs inaccessible by default	Final
JVM	Restore Always-Strict Floating Point Semantics	Strict FP behavior like earlier Java versions	Final
Security	Deprecate Security Manager	Security Manager marked for removal	Deprecated
Security	Remove RMI Activation	Removed outdated RMI activation mechanism	Removed
Security	Remove Experimental AOT & JIT Compiler	Removed jaotc and experimental Graal JIT	Removed
Garbage Collection	ZGC Improvements	Better performance & lower latency	Improved
Garbage Collection	Deprecate Applet API	Applets officially deprecated for removal	Deprecated

public sealed class Shape

permits Circle, Rectangle {}

final class Circle extends Shape {}

final class Rectangle extends Shape {}

Ø Controls inheritance
Better domain modeling

Before Java 17:

if (obj instanceof String) {

String s = (String) obj;

System.out.println(s.length());

}

Java 17:

if (obj instanceof String s) {

System.out.println(s.length());

}

✔ No explicit casting
✔ Cleaner code

static String format(Object obj) {

return switch (obj) {

case Integer i -> "Integer: " + i;

case String s -> "String: " + s;

default -> "Unknown";

};

}

RandomGenerator generator = RandomGenerator.getDefault();

int number = generator.nextInt();

✔ Multiple algorithms
✔ Better randomness control

Ø LTS version (supported long term)

Ø Stable for enterprise apps

Ø Better performance

Ø Stronger security

Ø Cleaner language features