Unable to compile simple Java 10 / Java 11 project with Maven

Solution 1:

As of 30Jul, 2018 to fix the above issue, one can configure the java version used within maven to any up to JDK/11 and make use of the maven-compiler-plugin:3.8.0 to specify a release of either 9,10,11 without any explicit dependencies.

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.8.0</version>
    <configuration>
        <release>11</release>  <!--or <release>10</release>-->
    </configuration>
</plugin>

Note:- The default value for source/target has been lifted from 1.5 to 1.6 with this version. -- release notes.

Edit [30.12.2018]

In fact, you can make use of the same version of maven-compiler-plugin while compiling the code against JDK/12 as well.

More details and a sample configuration in how to Compile and execute a JDK preview feature with Maven.

Solution 2:

UPDATE

The answer is now obsolete. See this answer.

maven-compiler-plugin depends on the old version of ASM which does not support Java 10 (and Java 11) yet. However, it is possible to explicitly specify the right version of ASM:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.7.0</version>
    <configuration>
        <release>10</release>
    </configuration>
    <dependencies>
        <dependency>
            <groupId>org.ow2.asm</groupId>
            <artifactId>asm</artifactId>
            <version>6.2</version> <!-- Use newer version of ASM -->
        </dependency>
    </dependencies>
</plugin>

You can find the latest at https://search.maven.org/search?q=g:org.ow2.asm%20AND%20a:asm&core=gav

Solution 3:

It might not exactly be the same error, but I had a similar one.

Check Maven Java Version

Since Maven is also runnig with Java, check first with which version your Maven is running on:

mvn --version | grep -i java 

It returns:

Java version 1.8.0_151, vendor: Oracle Corporation, runtime: C:\tools\jdk\openjdk1.8

Incompatible version

Here above my maven is running with Java Version 1.8.0_151. So even if I specify maven to compile with Java 11:

<properties>
    <java.version>11</java.version>
    <maven.compiler.source>${java.version}</maven.compiler.source>
    <maven.compiler.target>${java.version}</maven.compiler.target>
</properties>

It will logically print out this error:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.0:compile (default-compile) on project efa-example-commons-task: Fatal error compiling: invalid target release: 11 -> [Help 1]

How to set specific java version to Maven

The logical thing to do is to set a higher Java Version to Maven (e.g. Java version 11 instead 1.8).

Maven make use of the environment variable JAVA_HOME to find the Java Version to run. So change this variable to the JDK you want to compile against (e.g. OpenJDK 11).

Sanity check

Then run again mvn --version to make sure the configuration has been taken care of:

mvn --version | grep -i java

yields

Java version: 11.0.2, vendor: Oracle Corporation, runtime: C:\tools\jdk\openjdk11

Which is much better and correct to compile code written with the Java 11 specifications.

Solution 4:

Specify maven.compiler.source and target versions.

1) Maven version which supports jdk you use. In my case JDK 11 and maven 3.6.0.

2) pom.xml

<properties>
    <maven.compiler.source>11</maven.compiler.source>
    <maven.compiler.target>11</maven.compiler.target>
</properties>

As an alternative, you can fully specify maven compiler plugin. See previous answers. It is shorter in my example :)

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.0</version>
            <configuration>
                <release>11</release>
            </configuration>
        </plugin>
    </plugins>
</build>

3) rebuild the project to avoid compile errors in your IDE.

4) If it still does not work. In Intellij Idea I prefer using terminal instead of using terminal from OS. Then in Idea go to file -> settings -> build tools -> maven. I work with maven I downloaded from apache (by default Idea uses bundled maven). Restart Idea then and run mvn clean install again. Also make sure you have correct Path, MAVEN_HOME, JAVA_HOME environment variables.

I also saw this one-liner, but it does not work.

<maven.compiler.release>11</maven.compiler.release>

I made some quick starter projects, which I re-use in other my projects, feel free to check:

• https://github.com/yan-khonski-it/mvn-pmd-java11
• https://github.com/yan-khonski-it/pmd-java-14