Java 17 vs. Java 21

Attribute	Java 17	Java 21
Release Date	September 2021	September 2021
Feature Updates	Sealed classes, Pattern matching for switch, Records	Local-Variable Syntax for Lambda Parameters, Switch Expressions Enhancements
Performance Improvements	Yes	Yes
Security Enhancements	Yes	Yes
Tooling Support	Yes	Yes

Introduction

Java is a popular programming language that has been evolving over the years with new releases bringing in new features and improvements. In this article, we will compare the attributes of Java 17 and Java 21 to see how they differ and what new capabilities each version brings to the table.

Language Features

Java 17 introduced several language features such as sealed classes, pattern matching for switch statements, and records. Sealed classes allow developers to restrict which classes can be subclasses of a particular class, providing more control over the inheritance hierarchy. Pattern matching for switch statements simplifies code by allowing developers to destructure objects and extract values in a more concise way. Records provide a compact way to define classes that are used primarily for storing data.

On the other hand, Java 21 builds upon these language features by introducing new enhancements such as enhanced pattern matching for switch statements, local variable type inference for lambda parameters, and text blocks. Enhanced pattern matching for switch statements allows for more flexibility in matching patterns and extracting values, making code more readable and maintainable. Local variable type inference for lambda parameters reduces boilerplate code by inferring the types of lambda parameters based on the context in which they are used. Text blocks provide a more readable way to write multi-line strings in Java code.

Performance Improvements

Java 17 focused on improving performance with features such as the introduction of the vector API, which provides a set of vectorized operations for numerical computations. This allows developers to take advantage of hardware acceleration for improved performance in numerical computations. Additionally, Java 17 introduced the foreign function and memory API, which allows Java programs to interoperate with native code more efficiently.

Java 21 continues to improve performance with enhancements such as the introduction of the new JIT compiler, called GraalVM, as the default compiler. GraalVM is known for its high-performance capabilities and can optimize Java code more effectively, leading to better overall performance. Java 21 also includes improvements to the garbage collector, making memory management more efficient and reducing the impact on application performance.

Tooling and Developer Productivity

Java 17 introduced several improvements to tooling and developer productivity, such as the introduction of the jpackage tool for packaging Java applications as platform-specific installers. This makes it easier for developers to distribute their Java applications to end-users on different platforms. Java 17 also included updates to the Java Flight Recorder and Java Mission Control tools, providing developers with more insights into the performance of their applications.

Java 21 builds upon these improvements with enhancements such as the introduction of the new jpackage tool, which provides better support for modular applications and custom runtime images. This allows developers to create more optimized and efficient Java applications that can be easily distributed to end-users. Java 21 also includes updates to the Java Flight Recorder and Java Mission Control tools, providing developers with more advanced profiling and monitoring capabilities.

Conclusion

In conclusion, Java 17 and Java 21 both bring significant improvements to the Java programming language, with each version introducing new features and enhancements that improve developer productivity and application performance. While Java 17 introduced features such as sealed classes and pattern matching for switch statements, Java 21 builds upon these features with enhancements such as enhanced pattern matching and local variable type inference. Both versions also focus on improving performance with features such as the vector API and the new JIT compiler. Overall, Java developers can benefit from upgrading to the latest version of Java to take advantage of these new capabilities and improvements.