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java 21 features

Java 21 Features (java 21 features): The Ultimate Guide to What’s New in JDK 21

TECH SHITANSHU
java 21 features

Java 21 Features

With the new capabilities of Java 21, millions of developers are currently using more than 60 billion Java Virtual Machines (JVM) globally. For developers and businesses, Java remains the preferred development platform. The creation of Java applications is now more secure, stable, and performant thanks to this Java release. According to JSR 396 in the Java Community Process, the most recent long-term support (LTS) update of Oracle’s standard Java implementation, Java Development Kit (JDK) 21, contains a number of new features that we will learn about in depth.

Java has been the foundation of enterprise and backend programming for more than two decades. With the release of Java 21 (java 21 features), developers may enjoy one of the most feature-rich and performance-optimized versions in recent years.

In this detailed article, we will look at every major and minor feature present in Java 21 (java 21 features). Whether you’re a newbie or an experienced developer, this is your go-to resource for grasping Java 21’s capability.

✅ Java 21 was released in September 2023 and is a Long-Term Support (LTS) release.

Features of Java 21

Why Java 21 (java 21 features) is Important:

Java 21 is not just another version — it’s an LTS release, which means it will be supported for several years, making it ideal for production-grade applications.

Key Highlights:

  • Long-Term Support (LTS)

  • Major performance boosts

  • Enhanced language features

  • Better memory management

  • Greater support for native compilation

Java 21 is the bridge between modern Java (post-Java 8) and future innovation.

Below are Complete List of Java 21 Features (java 21 features)

✅ Final Features (Standard)

  1. String Templates (JEP 430)

  2. Unnamed Patterns and Variables (JEP 443)

  3. Record Patterns (JEP 440)

  4. Pattern Matching for Switch (JEP 441)

  5. Sequenced Collections (JEP 431)

  6. Virtual Threads (JEP 444)

🔍 Preview or Incubating Features:

  1. Scoped Values (JEP 446)

  2. Foreign Function & Memory API (JEP 442)

  3. Unnamed Classes and Instance Main Methods (JEP 445)

  4. Deprecation of Finalization (JEP 451)

Each of these Java 21 features (java 21 features) significantly enhances Java’s readability, maintainability, and performance.

1. String Templates

One of the features of java 21 is String templates allow text and expressions to be composed without using the + operator. The result is going to be a string,  but it can also be an object of another type. Each string template has a template processor that validates the text and expressions before composing them, achieving greater safety than basic ‘string interpolation’ features in other languages.

The following example declares a template expression which uses the template processor STR and contains one embedded expression, name:
       String name = “TechShitanshu”;

       String info = STR.”My name is \{name}”;

        System.out.println(info);

    It prints the following:

        My name is TechShitanshu

2. Pattern Matching for Switch (JEP 441)

This feature brings expressiveness and conciseness to switch statements.

java
switch (obj) { case String s -> System.out.println("It's a String"); case Integer i -> System.out.println("It's an Integer"); default -> System.out.println("Unknown type"); }

✅ Makes switch more type-safe and readable — a game changer for large applications.

3. Virtual Threads (JEP 444)

Java’s biggest concurrency upgrade in decades!

Virtual threads are lightweight and managed by the JVM, not OS.

🔹 Benefits:

  • Massive scalability

  • Ideal for high-concurrency apps (web servers, microservices)

  • Non-blocking performance

🔹 Code Sample:
java
Thread.startVirtualThread(() -> { System.out.println("Running async task"); });

4. Sequenced Collections (JEP 431)

Java 21 introduces a unified interface for ordered collections.

🔹 Features:

  • getFirst(), getLast()

  • Works with List, Deque, Queue

✅ Great for developing queues, sliding windows, and history logs.

5. Math.clamp() and StrictMath.clamp() Methods

To conveniently clamp the numerical value between the specified minimum and maximum values, the methods Math.clamp() and StrictMath.clamp() are added. For int, long, float, and double types, there are four overloads available in both Math and StrictMath classes. A long value can also be safely narrowed to int using a clamp(long value, int min, int max) overload.

6. Record Patterns (JEP 440)

🔹 Description:

Combines records and pattern matching for cleaner data handling.

🔹 Syntax:
java

record Person(String name, int age) {}

if (obj instanceof Person(String name, int age)) {
System.out.println(name + ” is “ + age + ” years old.”);
}

✅ Eliminates boilerplate code.

7. Unicode Emoji Properties

Below six new methods are added to java.lang.Character for obtaining Emoji character properties, which are defined in the Unicode Emoji Technical Standard (UTS #51) :

  • isEmoji(int codePoint)
  • isEmojiPresentation(int codePoint)
  • isEmojiModifier(int codePoint)
  • isEmojiModifierBase(int codePoint)
  • isEmojiComponent(int codePoint)
  • isExtendedPictographic(int codePoint)

8. Scoped Values (JEP 446 – Preview)

Scoped values offer a better alternative to thread-local variables.

🔹 Benefits:

  • Better data sharing across threads

  • Works perfectly with virtual threads

✅ Useful in concurrent processing, logging, or passing user context.

9. Foreign Function & Memory API (JEP 442 – 3rd Preview)

This is Java’s modern alternative to JNI (Java Native Interface).

🔹 Capabilities:

  • Directly call C libraries

  • Manage memory outside JVM

✅ High-performance applications like gaming engines and databases benefit hugely.

10. Unnamed Classes & Instance Main Methods (JEP 445 – Preview)

🔹 Java becomes more beginner-friendly!

This simplifies entry-level Java syntax:

java
void main() { System.out.println("Hello, Java 21!"); }

✅ Reduces ceremony for learning and scripting.

11. Deprecation of Finalization (JEP 451)

Finalization is finally being deprecated. It’s been error-prone and slow.

✅ Encourages developers to use try-with-resources and other reliable patterns.

12. Performance Improvements in Java 21 (java 21 features)

🔹 Enhancements:

  • Improved JIT compiler

  • Better GC pause time (G1 and ZGC)

  • Memory footprint reduction

  • Virtual threads reduce thread contention

✅ Java 21 is significantly faster than Java 17 or Java 11.

Java 21 vs Java 20

Feature Java 20 Java 21 (java 21 features)
LTS Support ❌ No ✅ Yes
Virtual Threads Preview ✅ Standard
Pattern Matching for Switch Preview ✅ Standard
Sequenced Collections ❌ No ✅ Yes
String Templates ❌ No ✅ Yes

Impact of new Java 21 Features (java 21 features) in Enterprise

Java 21 Tools Compatibility

Java 21 Release Date & Lifecycle

Internal Link for Java 21 (java 21 features)

➡️ Read more about Java’s evolution on TechShitanshu.com Java Guide

Java 21 Updates: What’s New in Java 21 (java 21 features)

Released: September 19, 2023
Support: Long-Term Support (LTS) until 2029
Version: JDK 21 (Java Development Kit 21)

Java 21 is one of the most significant updates in recent years. It introduces key language enhancements, performance improvements, and API upgrades that make Java more modern, expressive, and efficient.

Conclusion

Java 21 (java 21 features) proves that Java is not slowing down—it’s accelerating. From developer-friendly syntax to cutting-edge performance, Java 21 is a must-upgrade for modern teams.

Whether you’re working on legacy apps or building for the cloud, the java 21 features will shape how we write and maintain code for years to come.

So if you’re still on Java 11 or 17, it’s time to upgrade to Java 21 (java 21 features) and stay ahead of the curve.

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One response to “Java 21 Features (java 21 features): The Ultimate Guide to What’s New in JDK 21”
  1. The Major new functionality in Java 21 – TECH SHITANSHU

    […] is a preview feature and enhance the Java language with unnamed patterns, which match a record component without stating […]

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Shitanshu Kaushik

Shitanshu is a career software developer with a habit of finding novel ways to break things.

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