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Exploring JDK 21 new features: Java 21 Advancements with examples

Java is used worldwide. Its platform-independent, portable, and resilient nature attracts developers. The latest JDK 21 provides comprehensive knowledge for both new and experienced coders. Java provides many features.

What is JDK?

The JDK is a complete toolset for developing Java apps. It includes tools, utilities, and libraries for creating, building, debugging, and deploying Java programmes and applets. The JDK is built on the Java compiler, ‘javac’. The JVM understands and builds the translated bytecode at runtime. Aside from the compiler and JVM, the JDK provides tools such as the debugger ‘jdb’ and the executable file ‘.jar’, which bundle Java files into a single package for convenient distribution. JDK 21 introduces new capabilities and provides a complete environment for creating robotic and portable Java programmes.

Why Does Java 21 Need New Features? 

• Getting used to software updates and new issues.

• Adding new features in response to user input to promote contemporary coding and productive application development.

• Improving Java platform performance to enable speedier, less memory-intensive, and more responsive apps.

• Addressing known vulnerabilities and enhancing the overall security system.

• Producing Java Enhancement Proposals (JEPs) for feature addition.

• Improving compatibility with other technologies by introducing new tools, platforms, and services.

• Offering improved alternatives for outdated features.

• Produce predictable and consistent linguistic work.

• Efficient code writing using modern libraries, tools, and syntax.

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The Best New Features in Java 21

1. Language Feature

Better pattern matching in switch expressions and statements is now possible with Java 21’s Language feature, enabling developers to deconstruct complicated data. In switch scenarios, pattern matching is now included in this version, enabling developers to match sequences straight instead of verifying conditions. A further addition to Java 21 is the ‘String Template’ feature, which makes it simpler to combine expressions and code. With this version, nameless patterns and variables can now disregard the name or kind of data by using underscores.

2. Improvements to Libraries

JDK 21 includes virtual threads, which allow for efficient activities without needing considerable memory allocation. It also has sequenced collections, which allow developers to simply determine the order of objects in collections. Key encapsulation methods (KEM) are established to provide safe storage of secret keys. The vector API and vector tools are intended to improve performance in applications such as graphics rendering and scientific computing. These developments improve the overall capabilities of the Java platform.

3. Improved performance

Java’s Z Garbage Collection (ZBC) is a powerful cleaning tool that can conduct costly chores simultaneously without interfering with application thread execution. It separates unused memory into ‘new’ and ‘old’ notes to avoid memory cluttering and slowing down. ZGC divides unused memory into ‘new’ and ‘old’ notes, guaranteeing that newer notes are no longer required after a short period while older notes remain vital. By focusing on and cleaning up fresh information more regularly, ZBC keeps the memory desk simpler and more efficient.

4. Tool Enhancement

Java 21 offers better tools for creating new processes, such as ‘Runtime.exec’ and ‘ProcessBuilder’. This feature tracks or logs these operations, especially by monitoring the logger ‘java.lang.ProcessBuilder’. For example, to test a ping command, use ‘ProcessBuilder processBuilder’. The process details are continuously logged based on the logger’s level, which can be either DEBUG or TRACE. For example, if the log level is set to TRACE, the procedure will begin.

5. Java Emoji Compatibility Tools 

Java has added a method to the ‘java.lang.Character’ class that works with different emoji attributes as described by the Unicode Standard UTS#51. This function may detect if a given code leads to a unique integer that represents a character as an emoji or whether a code point is capable of having an emoji modifier applied, such as the hand emoji with varying skin tones.

6. Improved Lifecycle Management using HttpClient

The ‘HttpClient’ is now ‘AutoCloseable’, which means it may be used in a try-with-resources block in Java. JDK 21 has additional methods such as close(), shutdown(), shutdownNow(), awaitTerminationDuration(), and isTerminated() to manage resource closure when they are no longer required. Close() waits for active requests to complete before shutting, whereas shutdown() closes the HttpClient immediately with no waiting for all tasks to complete. The awaitTerminationDuration function waits for the client to shut down in a specified time frame, whereas isTerminated() determines if the HttpClient has completely shut down.

7. Enhanced Repetition of Adding an in StringBuilder and StringBuffer

JDK 21 adds capabilities to ‘java.lang.StringBuilder’ and ‘java.lang.StringBuffer’ that enable the insertion of Unicode characters or sequences numerous times. The int codePoint function adds the same letter repeatedly, but the CharSequence method adds a word or phrase several times. These techniques provide a neater, more succinct approach to appending repeated letters or sequences, removing the need for manual loops and enhancing code readability.

8. Developing Java Collections using Sequenced Interface 

The Java 21 version adds new interfaces to the Java collections framework, improving its explicit sequence order and enabling simple addition and removal of items from both the beginning and end. It also makes it easy to navigate lists from end to beginning, making them more natural and powerful. However, compatibility issues must be addressed while implementing these new functionalities.


Java’s followers are continually working to improve their apps with new features. The most recent version, JDK 21, shows Java’s ongoing progress by introducing new capabilities for both novices and professionals, making writing easier and faster. Java remains a favourite among Java experts, and those anxious to try out JDK 21 are excited to discover what new features it delivers.