Deleted Java 8 vs Java 11 vs Java 17 vs Java 21: A Comprehensive Comparison.md

-https://medium.com/@a.r.m.monesan_9577/java-8-vs-java-11-vs-java-17-vs-java-21-a-comprehensive-comparison-aa4635f9c3fe

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-# Java 8 vs Java 11 vs Java 17 vs Java 21: A Comprehensive Comparison | by amirreza moonesan | Medium

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-[amirreza moonesan](https://medium.com/@a.r.m.monesan_9577)

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-Java continues to evolve, with each new version bringing enhancements, deprecations, and new features. In this article, we’ll explore the differences between **Java 8**, **Java 11**, **Java 17**, and the latest **Java 21**. Understanding these differences can help developers and organizations decide which version is the best fit for their projects.

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-Table of Contents

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-1. Overview of Java Release Cycle

-2. Key Features of Each Java Version

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-* Java 8 (LTS)

-* Java 11 (LTS)

-* Java 17 (LTS)

-* Java 21 (LTS)

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-1. Performance Improvements

-2. New Language Features

-3. Tooling and API Enhancements

-4. Deprecations and Removed Features

-5. Migration Considerations

-6. Conclusion

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-1\. Overview of Java Release Cycle

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-Starting with Java 9, Oracle introduced a new **six-month release cycle**. This means a new Java version is released twice a year. However, **Long-Term Support (LTS)** versions — such as Java 8, 11, 17, and now 21 — are released every few years and are supported for longer periods.

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-2\. Key Features of Each Java Version

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-Java 8 (LTS)

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-Released in **March 2014**, Java 8 remains one of the most widely used versions of Java due to its stability and long support cycle. Key features include:

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-* **Lambda Expressions**: Enabled functional programming by allowing methods to be treated as first-class citizens.

-* **Streams API**: Provides a powerful way to process collections of objects.

-* **Default Methods**: Allowed interfaces to have method implementations, improving backward compatibility.

-* **Optional Class**: Reduces null checks and helps prevent `NullPointerException`.

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-Java 11 (LTS)

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-Released in **September 2018**, Java 11 was the first LTS after Java 8 and marked the start of a modern Java. Key features include:

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-* **Local-Variable Syntax for Lambda Parameters**: Use `var` in lambda expressions.

-* **HTTP Client (Standard)**: New `HttpClient` API replaces `HttpURLConnection`, with support for HTTP/2 and WebSockets.

-* **Nest-Based Access Control**: Improved encapsulation of nested classes.

-* **Deprecation of Pack200**: Various libraries were deprecated and removed, encouraging modernization.

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-Java 17 (LTS)

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-Released in **September 2021**, Java 17 is the most popular choice for LTS migration after Java 11. Key features include:

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-* **Sealed Classes**: Allows developers to define restricted class hierarchies.

-* **Pattern Matching for** `**instanceof**`: Simplifies type checking.

-* **Records**: Introduces compact syntax for immutable data classes.

-* **Strong Encapsulation by Default**: Further improves module system enforcement introduced in Java 9.

-* **Foreign Function & Memory API (Incubator)**: Facilitates better native interoperation.

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-Java 21 (LTS)

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-Released in **September 2023**, Java 21 brings significant new features and improvements:

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-* **Pattern Matching for Switch**: Adds a more expressive and safer switch.

-* **Record Patterns**: Enables pattern matching for record deconstruction.

-* **Virtual Threads (Project Loom)**: Lightweight threads to simplify writing high-throughput, scalable applications.

-* **Scoped Values**: An enhancement in Project Loom to enable flexible state passing in threads.

-* **Structured Concurrency (Incubator)**: Provides a model for concurrent tasks with lifecycles bound to parent tasks.

-* **Foreign Function & Memory API (Final)**: Finalized API for efficient interoperation with native code.

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-3\. Performance Improvements

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-Java 11 and beyond have introduced substantial performance improvements, particularly for garbage collection, startup time, and memory usage.

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-* **Java 8**: Uses Parallel GC by default.

-* **Java 11**: Introduces **Z Garbage Collector (ZGC)** and **G1GC** as the default GC for low-latency applications.

-* **Java 17**: G1GC and ZGC have been further optimized.

-* **Java 21**: Includes enhancements in **Virtual Threads** and improved garbage collection algorithms.

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-4\. New Language Features

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-A quick comparison of language feature improvements:

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-5\. Tooling and API Enhancements

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-* **Java 8**: Introduced some of the most widely adopted features like Lambda and Stream APIs.

-* **Java 11**: Introduced improvements like the new `HttpClient` and removed tools like `javaws`.

-* **Java 17**: Enhanced APIs like RandomGenerator, Stream, and Optional. Sealed Classes and Record Types became permanent.

-* **Java 21**: Includes finalized **Foreign Function & Memory API** and new APIs for structured concurrency.

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-6\. Deprecations and Removed Features

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-Each newer version of Java deprecates older features and removes unsupported APIs:

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-* **Java 11**: Removed deprecated modules like `java.xml.ws` and tools like `javaws`.

-* **Java 17**: Deprecated the Security Manager and finalized the removal of older APIs like Nashorn JavaScript Engine.

-* **Java 21**: Continues this trend by further deprecating outdated features, improving the overall performance and security of the language.

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-7\. Migration Considerations

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-Migrating from Java 8 or 11 to newer versions like Java 17 or 21 offers significant advantages in terms of performance and feature sets, but it can come with challenges:

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-* **Dependency Compatibility**: Some libraries or frameworks might not yet be compatible with newer Java versions.

-* **Newer APIs**: Adopting new APIs like the HTTP Client or Record Types may require code changes.

-* **Garbage Collection and Performance Tuning**: Newer versions bring optimized GCs, but they may require tuning based on application needs.

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-8\. Conclusion

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-* **Java 8**: Still widely used but lacks modern features.

-* **Java 11**: A stable LTS release, offering modern features while still being compatible with legacy systems.

-* **Java 17**: The most recommended LTS version due to its balance of modern features and long-term support.

-* **Java 21**: The latest LTS version, bringing cutting-edge features like **Virtual Threads** and **Structured Concurrency**.

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-Choosing the right Java version depends on your application’s specific needs, but moving towards the latest LTS versions like Java 17 or 21 will future-proof your application and provide performance improvements.

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-This article provides a clear comparison and roadmap for developers deciding between Java versions, emphasizing the improvements in performance, language features, and API tooling with each release.