Introduction
Java 17 was released on September 14, 2021. Java 17 is the next LTS version after Java 11. It’s expected that users of Java 11 will gradually migrate to Java 17. This book summaries all major changes from Java 11 to Java 17, so you can easily migrate from Java 11 to Java 17.
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Spring Framework 6 is released with requirements of JDK 17+, so you have to upgrade to JDK 17 to use Spring Framework 6. |
If you are currently using Java 8, then you may need to know how to upgrade from Java 8 to Java 11 first. You can check out my book Exploring Java 9 for changes in Java 9.
If you want to upgrade from Java 17 to Java 21, you can check out my book From Java 17 to Java 21.
Java Releases Schedule After Java 9
After Java 9, the Java community has adopted a new release mode. There will be a new Java release every six months, which means two releases per year. One version will be released in March, while the other version will be released in September. For example, Java 16 was released in March 2021, while Java 17 was released in September 2021.
For each release, there will be only six months support, until the next version is released. During these six months, there will be two quarterly security updates. For example, Java 15 only has the initially released version 15.0.0 and two security updates 15.0.1 and 15.0.2. After Java 16 is released, there will be no more updates for Java 15. You have to upgrade to Java 16 to get updates.
For most projects, it’s not practical to frequently update Java versions. Java also has LTS (Long-term support) versions. When using LTS versions, you can get updates for a long time. Java 8 and Java 11 are both LTS versions. Java 17 will be the next LTS version. For Java 11, you can get free public updates until at least 2024. Some companies offer free public updates for an extended period. So for most projects, LTS versions should be used.
JEPs in Different Java Releases
Java Enhancement Proposal (JEP) is used to organize changes to OpenJDK. A Java release may contain a list of JEPs. Below are lists of JEPs added in each Java release from Java 12 to Java 17.
Java 12
Java 12 has 8 JEPs, see the table below.
| Number | Name |
|---|---|
| 189 | Shenandoah: A Low-Pause-Time Garbage Collector (Experimental) |
| 230 | Microbenchmark Suite |
| 325 | Switch Expressions (Preview) |
| 334 | JVM Constants API |
| 340 | One AArch64 Port, Not Two |
| 341 | Default CDS Archives |
| 344 | Abortable Mixed Collections for G1 |
| 346 | Promptly Return Unused Committed Memory from G1 |
Java 13
Java 13 has 5 JEPs, see the table below.
| Number | Name |
|---|---|
| 350 | Dynamic CDS Archives |
| 351 | ZGC: Uncommit Unused Memory |
| 353 | Reimplement the Legacy Socket API |
| 354 | Switch Expressions (Preview) |
| 355 | Text Blocks (Preview) |
Java 14
Java 14 has 16 JEPs, see the table below.
| Number | Name |
|---|---|
| 305 | Pattern Matching for instanceof (Preview) |
| 343 | Packaging Tool (Incubator) |
| 345 | NUMA-Aware Memory Allocation for G1 |
| 349 | JFR Event Streaming |
| 352 | Non-Volatile Mapped Byte Buffers |
| 358 | Helpful NullPointerExceptions |
| 359 | Records (Preview) |
| 361 | Switch Expressions (Standard) |
| 362 | Deprecate the Solaris and SPARC Ports |
| 363 | Remove the Concurrent Mark Sweep (CMS) Garbage Collector |
| 364 | ZGC on macOS |
| 365 | ZGC on Windows |
| 366 | Deprecate the ParallelScavenge + SerialOld GC Combination |
| 367 | Remove the Pack200 Tools and API |
| 368 | Text Blocks (Second Preview) |
| 370 | Foreign-Memory Access API (Incubator) |
Java 15
Java 15 has 14 JEPs, see the table below.
| Number | Name |
|---|---|
| 339 | Edwards-Curve Digital Signature Algorithm (EdDSA) |
| 360 | Sealed Classes (Preview) |
| 371 | Hidden Classes |
| 372 | Remove the Nashorn JavaScript Engine |
| 373 | Reimplement the Legacy DatagramSocket API |
| 374 | Disable and Deprecate Biased Locking |
| 375 | Pattern Matching for instanceof (Second Preview) |
| 377 | ZGC: A Scalable Low-Latency Garbage Collector |
| 378 | Text Blocks |
| 379 | Shenandoah: A Low-Pause-Time Garbage Collector |
| 381 | Remove the Solaris and SPARC Ports |
| 383 | Foreign-Memory Access API (Second Incubator) |
| 384 | Records (Second Preview) |
| 385 | Deprecate RMI Activation for Removal |
Java 16
Java 16 has 17 JEPs, see the table below.
| Number | Name |
|---|---|
| 338 | Vector API (Incubator) |
| 347 | Enable C++14 Language Features |
| 357 | Migrate from Mercurial to Git |
| 369 | Migrate to GitHub |
| 376 | ZGC: Concurrent Thread-Stack Processing |
| 380 | Unix-Domain Socket Channels |
| 386 | Alpine Linux Port |
| 387 | Elastic Metaspace |
| 388 | Windows/AArch64 Port |
| 389 | Foreign Linker API (Incubator) |
| 390 | Warnings for Value-Based Classes |
| 392 | Packaging Tool |
| 393 | Foreign-Memory Access API (Third Incubator) |
| 394 | Pattern Matching for instanceof |
| 395 | Records |
| 396 | Strongly Encapsulate JDK Internals by Default |
| 397 | Sealed Classes (Second Preview) |
Java 17
Java 17 has 14 JEPs, see the table below.
| Number | Name |
|---|---|
| 306 | Restore Always-Strict Floating-Point Semantics |
| 356 | Enhanced Pseudo-Random Number Generators |
| 382 | New macOS Rendering Pipeline |
| 391 | macOS/AArch64 Port |
| 398 | Deprecate the Applet API for Removal |
| 403 | Strongly Encapsulate JDK Internals |
| 406 | Pattern Matching for switch (Preview) |
| 407 | Remove RMI Activation |
| 409 | Sealed Classes |
| 410 | Remove the Experimental AOT and JIT Compiler |
| 411 | Deprecate the Security Manager for Removal |
| 412 | Foreign Function & Memory API (Incubator) |
| 414 | Vector API (Second Incubator) |
| 415 | Context-Specific Deserialization Filters |
Install Java 17
You can get Java 17 binaries from several different places. Since Java 17 is a LTS version, many vendors will provide Java 17 releases. For most users, Eclipse Temurin is the best choice as it’s not vendor-specific.
- Download OpenJDK 17 build from jdk.java.net.
- Download Eclipse Temurin from Adoptium.
- Use IDE to download. IntelliJ IDEA can download JDK.
Below is the output of java -version for Eclipse Temurin 17.
1 openjdk version "17.0.13" 2024-10-15
2 OpenJDK Runtime Environment Temurin-17.0.13+11 (build 17.0.13+11)
3 OpenJDK 64-Bit Server VM Temurin-17.0.13+11 (build 17.0.13+11, mixed mode, sharing)
Build Tools
When using Java 17 with build tools, Maven or Gradle, you may need to add the --enable-preview argument to enable preview features. The following code shows an example of the configuration of Maven compiler plugin. jdk.incubator.foreign is an incubating module, so it needs to be added explicitly using --add-modules.
1 <plugin>
2 <groupId>org.apache.maven.plugins</groupId>
3 <artifactId>maven-compiler-plugin</artifactId>
4 <version>3.13.0</version>
5 <configuration>
6 <source>17</source>
7 <target>17</target>
8 <compilerArgs>
9 <arg>--enable-preview</arg>
10 <arg>--add-modules</arg>
11 <arg>jdk.incubator.foreign</arg>
12 </compilerArgs>
13 </configuration>
14 </plugin>
Source Code
Source code of this book can be found on GitHub.