Exploring Java's Latest Features: What's New in Java 17

Table of Contents

1. Sealed Classes
2. Pattern Matching for instanceof
3. Enhanced Pseudo - Random Number Generators
4. New macOS Rendering Pipeline
5. Deprecation of the Applet API
6. Conclusion
7. References

Sealed Classes

Fundamental Concepts

Sealed classes in Java 17 allow you to restrict which other classes or interfaces can extend or implement them. You can specify a permitted list of sub - classes, giving you more control over the class hierarchy. This helps in writing more maintainable and secure code by preventing unauthorized sub - classing.

Usage Methods

To define a sealed class, you use the sealed keyword, followed by the permits clause that lists the permitted sub - classes.

// Sealed class
sealed class Shape permits Circle, Rectangle {
    // Common methods for shapes can be defined here
}

// Permitted sub - class
final class Circle extends Shape {
    private double radius;

    public Circle(double radius) {
        this.radius = radius;
    }

    public double getRadius() {
        return radius;
    }
}

// Permitted sub - class
final class Rectangle extends Shape {
    private double length;
    private double width;

    public Rectangle(double length, double width) {
        this.length = length;
        this.width = width;
    }

    public double getLength() {
        return length;
    }

    public double getWidth() {
        return width;
    }
}

Common Practices

• Use sealed classes when you want to limit the set of sub - classes for a particular class or interface. For example, in a geometric shapes library, you may want to restrict the types of shapes that can be created.
• Combine sealed classes with pattern matching for more concise and type - safe code.

Best Practices

• Make the permitted sub - classes final to prevent further sub - classing. This further enforces the intended hierarchy.
• Keep the list of permitted sub - classes small and well - defined to maintain clarity.

Pattern Matching for instanceof

Fundamental Concepts

Pattern matching for instanceof simplifies the process of checking an object’s type and casting it. Instead of writing a separate instanceof check followed by a cast, you can do it in a single step.

Usage Methods

Object obj = "Hello, World!";
if (obj instanceof String str) {
    // str is already cast to String
    System.out.println(str.toUpperCase());
}

Common Practices

• Use pattern matching for instanceof in conditional statements where you need to check the type of an object and perform operations on it. For example, in a method that handles different types of objects, you can use pattern matching to handle each type appropriately.

Best Practices

• Use descriptive variable names for the pattern - matched variable. This makes the code more readable.
• Avoid over - complicating the pattern matching expressions. Keep them simple and focused.

Enhanced Pseudo - Random Number Generators

Fundamental Concepts

Java 17 provides enhanced support for pseudo - random number generators (PRNGs). It offers a more flexible and pluggable architecture, allowing you to choose from different PRNG algorithms easily.

Usage Methods

import java.util.random.RandomGenerator;
import java.util.random.RandomGeneratorFactory;

public class RandomNumberExample {
    public static void main(String[] args) {
        RandomGenerator random = RandomGeneratorFactory.of("L128X1024MixRandom").create();
        int randomNumber = random.nextInt(100);
        System.out.println("Random number: " + randomNumber);
    }
}

Common Practices

• Use the new PRNG API when you need to generate random numbers in your application. For example, in a game application, you can use it to generate random positions or scores.

Best Practices

• Choose the appropriate PRNG algorithm based on your application’s requirements. For example, if you need high - quality random numbers for cryptographic purposes, choose a more secure algorithm.
• Reuse the RandomGenerator instance whenever possible to improve performance.

New macOS Rendering Pipeline

Fundamental Concepts

Java 17 introduces a new rendering pipeline for macOS applications. This new pipeline provides better performance and compatibility with modern macOS systems.

Usage Methods

There is no direct code - level usage for this feature. It is mainly an internal improvement by the Java development team. However, if you are developing Java applications for macOS, you will benefit from the improved rendering performance.

Common Practices

• When developing Java GUI applications for macOS, simply use the standard Java GUI libraries (such as JavaFX or Swing). The new rendering pipeline will be used automatically.

Best Practices

• Keep your Java version up - to - date to ensure you are getting the latest improvements in the rendering pipeline.

Deprecation of the Applet API

Fundamental Concepts

The Applet API has been deprecated in Java 17. Applets were small Java applications that could be embedded in web pages. With the decline in the use of applets due to security and performance issues, Java has decided to deprecate this API.

Usage Methods

Since it is deprecated, you should avoid using the Applet API in new Java projects. If you have existing projects that use the Applet API, you should consider migrating them to other technologies, such as web - based JavaScript frameworks.

Common Practices

• If you are maintaining an old Java project that uses applets, start planning the migration process as soon as possible.
• Educate your development team about the deprecation of the Applet API to prevent new code from using it.

Best Practices

• Use modern web technologies for creating interactive web - based applications instead of relying on applets.

Conclusion

Java 17 brings several exciting new features and improvements that enhance developer productivity and performance. Sealed classes provide better control over class hierarchies, pattern matching for instanceof simplifies type checking and casting, enhanced PRNGs offer more flexibility in random number generation, the new macOS rendering pipeline improves GUI performance on macOS, and the deprecation of the Applet API encourages the use of modern web technologies. By understanding and using these new features, Java developers can write more maintainable, secure, and efficient code.

References

• Java 17 Release Notes
• The Java Tutorials