Built by Maven

Setting the --release of the Java Compiler

Starting with JDK 9, the javac executable can accept the --release option to specify against which Java SE release you want to build the project. For example, you have JDK 17 installed and used by Maven, but you want to build the project against Java 11. The --release option ensures that the code is compiled following the rules of the programming language of the specified release, and that generated classes target the release as well as the public API of that release. This means that, unlike the old --source and --target options, the compiler will detect and generate an error when using APIs that don't exist in previous releases of Java SE.

The preferred was to specify the release depends on the Maven version in use.

Maven 3

Since version 3.6 of the Compiler Plugin, this option can be provided either via a property:

<project>
  [...]
  <properties>
    <maven.compiler.release>8</maven.compiler.release>
  </properties>
  [...]
</project>

or by configuring the plugin directly:

<project>
  [...]
  <build>
    [...]
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>...</version>
        <configuration>
          <release>11</release>
        </configuration>
      </plugin>
    </plugins>
    [...]
  </build>
  [...]
</project>

Maven 4

Since version 4 of the compiler plugin, which requires Maven 4, the preferred way to specify the release is together with the source declaration. This is the recommended way because it makes the creation of multi-release projects easier.

<project>
  [...]
  <sources>
    <source>
      <targetVersion>11</targetVersion>
    </source>
  </sources>
  [...]
</project>

Note: The value in the release parameter follows Java's new Version-String Scheme (JEP 223) adopted since Java 9. As such, the release number does not start with 1.x anymore. Also note that the supported release targets include the release of the currently used JDK plus a limited number of previous releases.