Java Version Comparator

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Java 17

LTS

Released: Sep 2021
Class file version: 61
Spring Boot: Supported by Spring Boot 3.x and 4.x. Virtual threads need Java 21.

Java 25

LTS

Released: Sep 2025
Class file version: 69
Spring Boot: Supported by Spring Boot 3.x and 4.x; spring.threads.virtual.enabled=true turns on virtual threads.

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34 changes from Java 17 to 25, 6 of them removals or breaking changes

Check the removed / breaking items before upgrading

They are the usual reasons an application compiles on Java 17 but fails on Java 25. Run jdeps --jdk-internals on your JARs to find uses of JDK internals.

Java 18Mar 2022
- APIs
  UTF-8 by default
  Files and streams default to UTF-8 on every OS, not the platform charset.
  JEP 400
- Tools
  Simple web server
  jwebserver serves a directory over HTTP.
  JEP 408
- Tools
  Code snippets in Javadoc
  {@snippet} for compilable examples.
  JEP 413
- Removed / breaking
  Finalization deprecated for removal
  Use Cleaner or try-with-resources instead of finalize().
  JEP 421
Java 21LTSSep 2023
- APIs
  Virtual threads
  Executors.newVirtualThreadPerTaskExecutor(): millions of cheap threads for blocking I/O.
  JEP 444
- Language
  Pattern matching for switch
  switch (shape) { case Circle c -> …; case Square s -> …; }
  JEP 441
- Language
  Record patterns
  if (obj instanceof Point(int x, int y)) …
  JEP 440
- APIs
  Sequenced collections
  getFirst(), getLast(), reversed() on List, Deque, LinkedHashSet and LinkedHashMap.
  JEP 431
- JVM & GC
  Generational ZGC
  ZGC with generations for better throughput.
  JEP 439
- APIs
  Key Encapsulation Mechanism API
  JEP 452
- Removed / breaking
  Dynamic agent loading warns
  Agents attached at runtime print a warning; load them with -javaagent instead.
  JEP 451
Java 22Mar 2024
- Language
  Unnamed variables and patterns
  catch (Exception _) and case Point(var x, _).
  JEP 456
- APIs
  Foreign Function & Memory API
  Call native code and manage off-heap memory without JNI.
  JEP 454
- Tools
  Multi-file source programs
  java Main.java can use other source files.
  JEP 458
- JVM & GC
  Region pinning for G1
  No more GC stalls during JNI critical regions.
  JEP 423
Java 23Sep 2024
- Tools
  Markdown documentation comments
  /// comments in Markdown.
  JEP 467
- JVM & GC
  Generational mode by default for ZGC
  JEP 474
- Removed / breaking
  sun.misc.Unsafe memory access deprecated for removal
  Libraries should move to VarHandle and the FFM API.
  JEP 471
Java 24Mar 2025
- APIs
  Stream gatherers
  Custom intermediate operations: stream.gather(Gatherers.windowFixed(3)).
  JEP 485
- APIs
  Class-File API
  Read and write class files without ASM.
  JEP 484
- JVM & GC
  Virtual threads no longer pin on synchronized
  synchronized blocks no longer tie a virtual thread to its carrier.
  JEP 491
- JVM & GC
  Ahead-of-time class loading and linking
  Faster startup from a training run's cache.
  JEP 483
- APIs
  Quantum-resistant cryptography
  ML-KEM and ML-DSA.
  JEP 496
- Removed / breaking
  Security Manager permanently disabled
  Enabling it at startup or runtime fails.
  JEP 486
- Removed / breaking
  Windows 32-bit x86 port removed
  JEP 479
Java 25LTSSep 2025
- Language
  Compact source files and instance main methods
  void main() { IO.println("Hello"); } in a file without a class.
  JEP 512
- Language
  Module import declarations
  import module java.base; imports every package of a module.
  JEP 511
- Language
  Flexible constructor bodies
  Statements before super(…), e.g. to validate arguments.
  JEP 513
- APIs
  Scoped values
  Share immutable data with callees and child threads; the virtual-thread-friendly ThreadLocal.
  JEP 506
- APIs
  Key Derivation Function API
  JEP 510
- JVM & GC
  Compact object headers
  Smaller object headers (-XX:+UseCompactObjectHeaders) cut heap use.
  JEP 519
- JVM & GC
  AOT method profiling and simpler AOT cache creation
  Faster warm-up from a training run.
  JEP 515
- JVM & GC
  Generational Shenandoah
  Production-ready.
  JEP 521
- Removed / breaking
  32-bit x86 port removed
  JEP 503

Compare Java 8, 11, 17, 21 and 25 features and changes.

How to use the Java Version Comparator

Pick the Java version you run today and the one you're moving to, or click a common upgrade.
Read the changes release by release. Filter by category, or show preview features too.
Before upgrading, work through the Removed / breaking items: removed modules, stronger encapsulation and changed defaults.

What is an LTS release?

A new Java version ships every six months. Every two years one of them is a long-term support (LTS) release that vendors keep patching for years: Java 8, 11, 17, 21 and 25. Most teams move from one LTS to the next.

Frequently asked questions

What does "Unsupported class file major version 65" mean?

The class was compiled for a newer Java than the one running it (or than a tool such as an old Gradle or ASM supports). The class file version is the Java version plus 44, so 65 is Java 21. The Java Stack Trace Analyzer explains this and other errors.

What breaks most often when upgrading from Java 8?

JAXB and the other Java EE modules (removed in 11: add them as dependencies), libraries that use JDK internals (blocked since 16 and 17: upgrade them or add --add-opens) and old build plugins or bytecode tools that don't understand the new class file version.

Which features need --enable-preview?

Preview features must be switched on with --enable-preview both when compiling and when running, and can change in the next release. The list hides them by default; the release that made each one final lists it as usual.

All tools

Java 18Mar 2022

Java 21LTSSep 2023

Java 22Mar 2024

Java 23Sep 2024

Java 24Mar 2025

Java 25LTSSep 2025