Exploring the New Features of Java 17: What Developers Need to Know

Java 17, released on September 14, 2021, is the latest Long-Term Support (LTS) release from Oracle, bringing with it a host of new features and improvements. As developers, it’s essential to stay updated with the latest enhancements to leverage the full potential of the language and platform. In this article, we’ll dive into the key features and changes introduced in Java 17 that can help streamline your development process and improve your applications.

1. Sealed Classes and Interfaces

One of the most anticipated features in Java 17 is sealed classes and interfaces. This feature allows you to control which classes or interfaces can extend or implement them, providing better control over the class hierarchy and ensuring more robust design.

public abstract sealed class Shape permits Circle, Square, Rectangle {}

public final class Circle extends Shape {}
public final class Square extends Shape {}
public final class Rectangle extends Shape {        

By using sealed classes, you can enforce stricter control over the class hierarchy, making your code more maintainable and secure.

2. Pattern Matching for Switch (Preview)

Pattern matching for switch statements simplifies the code and enhances readability by allowing more expressive and concise patterns. This feature is still in preview but offers a glimpse into the future of switch statements in Java.

public String formatter(Object obj) {
    return switch (obj) {
        case Integer i -> String.format("int %d", i);
        case Long l -> String.format("long %d", l);
        case Double d -> String.format("double %f", d);
        case String s -> String.format("String %s", s);
        default -> obj.toString();
    };
}        

This feature reduces boilerplate code and makes switch statements more powerful and flexible.

3. Strong Encapsulation of JDK Internals

Java 17 enforces strong encapsulation of internal APIs, which enhances the security and maintainability of the platform. By restricting access to internal APIs, Java ensures that applications are more robust and less likely to break due to internal changes.

4. Removal of the Applet API

The Applet API, once a popular way to embed Java applications in web browsers, has been deprecated and removed in Java 17. This change streamlines the JDK and removes outdated and rarely used features, allowing developers to focus on more modern approaches.

5. New MacOS Rendering Pipeline

Java 17 introduces a new rendering pipeline for MacOS, providing better performance and integration with the MacOS ecosystem. This change ensures that Java applications run more smoothly and efficiently on MacOS devices.

6. Enhanced Pseudo-Random Number Generators

Java 17 brings new interfaces and implementations for pseudo-random number generation, offering more flexibility and power for applications requiring random data. The new API includes support for various algorithms and enhancements to existing ones.

RandomGenerator generator = RandomGeneratorFactory.of("L128X256MixRandom").create();
int randomValue = generator.nextInt();        

This feature allows developers to choose the best-suited random number generator for their specific use case.

7. Deprecate and Future Removal of RMI Activation

Java 17 deprecates the RMI Activation framework, with plans for future removal. This change is part of an ongoing effort to modernize the platform and remove less-used features. Developers are encouraged to explore alternative solutions for remote method invocation.

8. Foreign Function & Memory API (Incubator)

The Foreign Function & Memory API, introduced as an incubator feature, provides a more efficient and safer way to interact with native code. This API allows Java applications to call native libraries and access native memory without the complexities and risks associated with JNI.

9. Vector API (Second Incubator)

The Vector API, now in its second incubator phase, introduces first-class support for vector computations, enabling developers to harness the power of SIMD (Single Instruction, Multiple Data) for performance-intensive tasks. This feature is particularly useful for applications requiring high-performance computations.

Vector<Short> v1 = ShortVector.fromArray(SPECIES, shortArray, 0);
Vector<Short> v2 = ShortVector.fromArray(SPECIES, shortArray, SPECIES.length());
Vector<Short> v3 = v1.add(v2);
v3.intoArray(resultArray, 0);        

This API provides a way to write more efficient code by leveraging the parallel processing capabilities of modern CPUs.

10. Deprecation of the Security Manager for Removal

The Security Manager, which has been part of Java since version 1.0, is deprecated for removal in a future release. This move reflects the fact that most applications and libraries no longer rely on it, and other mechanisms have emerged to provide security and sandboxing.

11. New JDK Flight Recorder (JFR) Event Streaming

Java 17 enhances JDK Flight Recorder (JFR) by introducing event streaming capabilities. This allows continuous monitoring and logging of JFR events, which can help in real-time performance analysis and troubleshooting.

try (var es = new EventStream()) {
    es.onEvent("jdk.CPULoad", event -> {
        System.out.println(event);
    });
    es.start();
}        

This feature provides a powerful tool for developers to monitor and debug applications more effectively.

12. Enhanced JavaDoc

Java 17 improves the JavaDoc tool, making it more useful and user-friendly. Enhancements include improved search functionality, better HTML rendering, and additional tags that help document code more effectively.

13. Enhanced Deprecation

Java 17 introduces enhanced deprecation, providing more detailed information about deprecated APIs. This includes suggestions for alternatives and information about when the API will be removed.

@Deprecated(forRemoval = true, since = "17")
public void oldMethod() {
    // ...
}        

This helps developers manage the lifecycle of their code and plan for future changes.

Conclusion

Java 17 is a significant release that brings many new features and enhancements to the language and platform. From sealed classes and pattern matching to improved random number generators and new APIs for native code interaction, Java 17 has something for every developer. Additionally, the deprecation of outdated features and enhancements to tools like JavaDoc and JFR make Java 17 a robust and modern platform for building applications.

As an LTS release, Java 17 offers a stable and robust foundation for building the next generation of Java applications. By adopting Java 17, developers can take advantage of these new features to write cleaner, more maintainable, and more efficient code. Stay updated and explore these new capabilities to enhance your Java development experience.

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