Last checked and updated on 19 May 2026
What is New in Java 17
Java 17 is a Long-Term Support (LTS) release that brings several important language improvements, security enhancements, and performance updates. It stabilizes features like sealed classes and pattern matching for switch, removes outdated components, and prepares the platform for modern development needs.
Sealed Classes (Standard)
Sealed classes and interfaces restrict which other classes or interfaces may extend or implement them. This provides better control over inheritance and makes code more predictable.
public abstract sealed class Shape
permits Circle, Rectangle, Square {
// class body
}
public final class Circle extends Shape { ... }
public final class Rectangle extends Shape { ... }
public non-sealed class Square extends Shape { ... }Pattern Matching for switch (Preview)
Switch statements and expressions now support type patterns and guarded patterns. This reduces boilerplate and handles null cases safely.
String formatted = switch (obj) {
case Integer i -> "int " + i;
case Long l -> "long " + l;
case Double d -> "double " + d;
case String s -> "String " + s;
default -> obj.toString();
};Security Enhancements
Context-Specific Deserialization Filters
New factory method allows different filters for each deserialization operation, improving security against malicious data streams.
Stronger Pseudorandom Number Generators
New implementations provide better randomness for security-sensitive applications.
Deprecate the Security Manager for Removal
The old Security Manager is marked for future removal as it is rarely used and replaced by modern alternatives.
Platform and Runtime Updates
Support for macOS/AArch64
Official ports for Apple Silicon (ARM-based Macs) with improved performance.
New macOS Rendering Pipeline
Switches to the Metal API for better graphics performance on macOS.
Foreign Function & Memory API (Incubator)
Safe and efficient access to native code and memory outside the Java heap.
Vector API (Incubator)
Reliable runtime compilation for high-performance vector operations.
Removals and Deprecations
| Feature | Status |
|---|---|
| RMI Activation Mechanism | Removed |
| Experimental AOT and JIT Compiler (jaotc) | Removed |
| Security Manager | Deprecated for removal |
| Old Applets API | Further deprecated |
Other Notable Changes
- Hidden classes cannot be discovered by default for better encapsulation.
- Improved support for containers with better CPU awareness.
- Enhanced pseudo-random number generators with new algorithms.
- Updated flight recorder for better low-overhead profiling.
- Thousands of bug fixes and small performance improvements.
Why Choose Java 17
As a Long-Term Support release, Java 17 offers extended updates and stability for production environments. It combines mature language features with modern security and platform support, making it a solid upgrade path from Java 11 or earlier versions. Developers gain cleaner code through sealed classes and pattern matching while benefiting from improved performance on new hardware.