无法执行目标 org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile)

Question

i want to generate a jar but every time I get this error

Console logs

[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.160 s
[INFO] Finished at: 2021-11-27T00:37:06+01:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler- 
 plugin:3.1:compile (default-compile) on project qengine: Fatal error compiling: invalid 
 target release: 9 -> [Help 1]

[ERROR] [ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch. [ERROR] Re-run Maven using the -X switch to enable full debug logging. [ERROR] [ERROR] For more information about the errors and possible solutions, please read the following articles: [ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionExceptions

---

4.0.0 napd qengine 0.0.1-SNAPSHOT

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.eclipse.rdf4j</groupId>
            <artifactId>rdf4j-bom</artifactId>
            <version>3.7.3</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>


<dependencies>


    <dependency>
        <groupId>org.eclipse.rdf4j</groupId>
        <artifactId>rdf4j-client</artifactId>
        <type>pom</type>
    </dependency>


    <dependency>
        <groupId>org.apache.jena</groupId>
        <artifactId>apache-jena</artifactId>
        <type>pom</type>
        <version>3.9.0</version>
    </dependency>
</dependencies>


<build>
    <plugins>
        <!-- <plugin> <artifactId>maven-compiler-plugin</artifactId> <version>3.8.1</version> 
            <configuration> <source>8</source> <target>8</target> </configuration> </plugin> 
            <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-jar-plugin</artifactId> 
            <configuration> <archive> <manifest> <mainClass>qengine.Main</mainClass> 
            </manifest> </archive> </configuration> </plugin> -->
    
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-dependency-plugin</artifactId>
            <version>3.2.0</version>
            <executions>
                <execution>
                    <id>copy-dependencies</id>
                    <phase>package</phase>
                    <goals>
                        <goal>copy-dependencies</goal>
                    </goals>
                    <configuration>
                        <outputDirectory>${project.build.directory}/allJars</outputDirectory>
                        <overWriteReleases>false</overWriteReleases>
                        <overWriteSnapshots>false</overWriteSnapshots>
                        <overWriteIfNewer>true</overWriteIfNewer>
                    </configuration>
                </execution>
            </executions>
        </plugin>

        <!-- <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> 
            <configuration> <source>9</source> <target>9</target> </configuration> </plugin> -->

        <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
            <source>9</source>
            <target>9</target>
        </configuration>
    </plugin>
        
    </plugins>
</build>

Answer 1

(1) Is the JAVA_HOME variable configured to the JDK 1.9 path?

(2) Try replacing the configuration for maven-compiler-plugin :

<configuration>
  <fork>true</fork>
  <executable>javac9</executable>
</configuration>