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What's New in Java 21

  • Writer: V V
    V V
  • Jun 2, 2024
  • 3 min read

Java 21, the latest LTS version of the popular programming language, introduces a plethora of new features and enhancements. This post provides a look at the key innovations presented in this release, based on official documentation. Additionally, we will review the new features introduced in Java 18, 19, and 20.


Java 21

New Features in Java 21

1. Record Types

Record Types offer a simplified way to create immutable objects. They automatically generate constructors, getters, equals(), hashCode(), and toString() methods.

2. Switch Patterns

Switch Patterns allow the use of patterns directly in switch statements, making them more expressive.

3. Sealed Classes

Sealed Classes restrict which classes can extend or implement them, allowing developers to control class hierarchies.

4. Record Patterns

Introduced in Java 21, Record Patterns allow for more efficient use of patterns with records in instanceof and switch expressions.

5. Vector API

The Vector API provides a new way to handle vector data for high-performance computations.

6. Foreign Function & Memory API

The Foreign Function & Memory API (FFM API) provides a new way to interact with code and data outside the JVM, enabling safe and efficient use of native libraries.

7. Scoped Values

Scoped Values replace ThreadLocal for passing data through call chains, making code less error-prone.

8. Compiler Optimizations

Java 21 includes numerous compiler optimizations that enhance code performance, including improvements to the JIT (Just-In-Time) compiler and new capabilities for AOT (Ahead-Of-Time) compilation.

9. Support for New Hardware Architectures

Support for new hardware architectures, such as ARM64, allows Java to run efficiently on various devices, including servers and mobile devices.

10. Collections Updates

The Collections library has new methods that simplify working with collections, such as the toList() method for the Stream API.

11. Sequenced Collections

New interfaces for ordered collections, such as SequencedCollection, SequencedMap, and SequencedSet, have been introduced.

12. New Methods in String

New methods String.indexOf(int ch, int beginIndex, int endIndex) and String.indexOf(String str, int beginIndex, int endIndex) support index ranges for searching characters and strings.

13. Security Enhancements

Java 21 includes updates to encryption algorithms and improvements to standard libraries to protect applications from modern threats.

14. Improved Memory Management

Garbage collectors ZGC and Shenandoah continue to improve, providing more efficient memory management and reducing pause times.

15. String Templates (Preview)

String Templates provide a convenient way to embed expressions within string literals. This feature enhances readability and helps avoid common pitfalls like SQL injection by ensuring secure string construction.

16. Unnamed Patterns and Variables (Preview)

Unnamed patterns and variables, indicated by an underscore (_), allow developers to ignore specific variables or patterns that are not used, simplifying the code.


17. Unnamed Classes and Instance Main Methods (Preview)

Java 21 allows writing and running simple programs without explicitly defining a class. This is particularly useful for beginners and quick prototyping.

18. Virtual Threads

Virtual threads in Java 21 enable the creation of millions of lightweight threads, making it easier to write scalable concurrent applications.

New Features in Java 18, 19, and 20

Java 18

  1. UTF-8 by Default - UTF-8 is now the default charset, enhancing international support.

  2. Simple Web Server - A lightweight built-in web server for testing and debugging.

  3. Vector API (Third Incubation) - Continued development of the Vector API for SIMD instructions.

Java 19

  1. Virtual Threads (Project Loom, preview) - Virtual threads simplify multithreaded development.

  2. Structured Concurrency (preview) - Ensures convenient and safe parallelism management.

  3. Pattern Matching for switch (Fourth Incubation) - Continued development of pattern matching for switch.

Java 20

  1. Scoped Values (preview) - Local values for safer data management in multithreaded applications.

  2. Foreign Function & Memory API (Third Incubation) - Continued development of the API for interacting with native libraries.

  3. Pattern Matching for switch (Fifth Incubation) - Further enhancements to pattern matching for switch.

Conclusion

Java 21 represents a significant step forward in the development of the programming language and platform. New features and improvements make development more efficient and convenient. Record Types, switch patterns, Sealed Classes, and new APIs such as Vector API and Foreign Function & Memory API highlight the language's ongoing evolution. The enhancements in security, compiler optimizations, and support for new hardware architectures further solidify Java's position as a robust and versatile programming language.

We highly recommend upgrading to the latest version to take full advantage of all the new features and improvements Java 21 has to offer. Happy coding!

For more information, you can refer to the official Java 21 documentation.

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