Java/Java 8 vs Java 11 vs Java 17 vs Java 21 - A Comprehensive Comparison.md
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+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://miro.medium.com/v2/resize:fill:88:88/1*sxiMiGMfNGe5n-_GdSWaIw.jpeg)
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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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+-----------------
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+1. Overview of Java Release Cycle
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+2. Key Features of Each Java Version
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+
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+* Java 8 (LTS)
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+* Java 11 (LTS)
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+* Java 17 (LTS)
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+* Java 21 (LTS)
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+1. Performance Improvements
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+2. New Language Features
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+3. Tooling and API Enhancements
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+4. Deprecations and Removed Features
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+5. Migration Considerations
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+6. Conclusion
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+1\. Overview of Java Release Cycle
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+----------------------------------
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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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+![](https://miro.medium.com/v2/resize:fit:720/format:webp/1*OMT2HWZOra_UEgo5h8Dc0w.png)
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+2\. Key Features of Each Java Version
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+-------------------------------------
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+Java 8 (LTS)
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+------------
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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.
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+* **Streams API**: Provides a powerful way to process collections of objects.
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+* **Default Methods**: Allowed interfaces to have method implementations, improving backward compatibility.
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+* **Optional Class**: Reduces null checks and helps prevent `NullPointerException`.
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+Java 11 (LTS)
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+-------------
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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.
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+* **HTTP Client (Standard)**: New `HttpClient` API replaces `HttpURLConnection`, with support for HTTP/2 and WebSockets.
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+* **Nest-Based Access Control**: Improved encapsulation of nested classes.
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+* **Deprecation of Pack200**: Various libraries were deprecated and removed, encouraging modernization.
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+Java 17 (LTS)
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+-------------
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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.
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+* **Pattern Matching for** `**instanceof**`: Simplifies type checking.
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+* **Records**: Introduces compact syntax for immutable data classes.
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+* **Strong Encapsulation by Default**: Further improves module system enforcement introduced in Java 9.
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+* **Foreign Function & Memory API (Incubator)**: Facilitates better native interoperation.
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+Java 21 (LTS)
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+-------------
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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.
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+* **Record Patterns**: Enables pattern matching for record deconstruction.
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+* **Virtual Threads (Project Loom)**: Lightweight threads to simplify writing high-throughput, scalable applications.
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+* **Scoped Values**: An enhancement in Project Loom to enable flexible state passing in threads.
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+* **Structured Concurrency (Incubator)**: Provides a model for concurrent tasks with lifecycles bound to parent tasks.
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+* **Foreign Function & Memory API (Final)**: Finalized API for efficient interoperation with native code.
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+3\. Performance Improvements
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+----------------------------
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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.
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+* **Java 11**: Introduces **Z Garbage Collector (ZGC)** and **G1GC** as the default GC for low-latency applications.
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+* **Java 17**: G1GC and ZGC have been further optimized.
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+* **Java 21**: Includes enhancements in **Virtual Threads** and improved garbage collection algorithms.
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+4\. New Language Features
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+-------------------------
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+A quick comparison of language feature improvements:
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+![](https://miro.medium.com/v2/resize:fit:720/format:webp/1*4QbOiNQnp8omayYV5likdg.png)
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+5\. Tooling and API Enhancements
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+--------------------------------
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+* **Java 8**: Introduced some of the most widely adopted features like Lambda and Stream APIs.
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+* **Java 11**: Introduced improvements like the new `HttpClient` and removed tools like `javaws`.
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+* **Java 17**: Enhanced APIs like RandomGenerator, Stream, and Optional. Sealed Classes and Record Types became permanent.
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+* **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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+-------------------------------------
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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`.
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+* **Java 17**: Deprecated the Security Manager and finalized the removal of older APIs like Nashorn JavaScript Engine.
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+* **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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+----------------------------
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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.
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+* **Newer APIs**: Adopting new APIs like the HTTP Client or Record Types may require code changes.
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+* **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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+--------------
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+* **Java 8**: Still widely used but lacks modern features.
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+* **Java 11**: A stable LTS release, offering modern features while still being compatible with legacy systems.
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+* **Java 17**: The most recommended LTS version due to its balance of modern features and long-term support.
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+* **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.
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