Maven Not Using JDK 11

Question

I recently downloaded the JDK11 and the OpenJ9 JRE for JDK11. I have set the Java classpath fine.

When I run java -version command I get:

openjdk version "11.0.10" 2021-01-19
OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.10+9)
Eclipse OpenJ9 VM AdoptOpenJDK (build openj9-0.24.0, JRE 11 Windows 10 amd64-64-Bit Compressed References 20210120_899 (JIT enabled, AOT enabled)
OpenJ9   - 345e1b09e
OMR      - 741e94ea8
JCL      - 0a86953833 based on jdk-11.0.10+9)

But my Maven is still pointing to the old Java8 that I have installed. Running mvn -version gives me:

Apache Maven 3.6.3 (cecedd343002696d0abb50b32b541b8a6ba2883f)
Maven home: H:\apache-maven-3.6.3\bin\..
Java version: 1.8.0_271, vendor: Oracle Corporation, runtime: C:\Program Files\Java\jdk1.8.0_271\jre
Default locale: en_US, platform encoding: Cp1252
OS name: "windows 10", version: "10.0", arch: "amd64", family: "windows"

Hence when I compile a maven module I get the following error:

Caused by: java.lang.IllegalArgumentException: invalid target release: 11

I have this set in my parent pom.xml:

<properties>

    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    
    <maven.compiler.target>11</maven.compiler.target>
    <maven.compiler.source>11</maven.compiler.source>

If you want to override java version for Maven, you need to set `JAVA_HOME` environment variable. — Ali Can, Feb 24 '21 at 13:59
`java -version` gives you "the first from `${PATH}`", whereas maven (if you not hacked the built in scripts) relies heavily on `${JAVA_HOME}` environment variable... — xerx593, Feb 24 '21 at 14:12
My `JAVA_HOME` is set to `C:\Program Files\Java\jdk-11.0.10` — hell_storm2004, Feb 24 '21 at 14:21
Your output would seem to suggest otherwise. What does `echo %JAVA_HOME%` print out? — Gimby, Feb 24 '21 at 14:26
Same as above. It prints the JDK 11 path. I will try to upload a screenshot to my original post. — hell_storm2004, Feb 24 '21 at 14:42
Okay, but the reason for this train of comments is because this is how it is documented to work and how it has worked for many years; it works like that for me right now. So then when I see a situation where the reality is deviating from how it is supposed to work, I can only assume a human has intervened somewhere. For example by manually editing the mvn.cmd file. — Gimby, Feb 24 '21 at 15:27
yes, from your screenshot, this is the only possible conclusion: Someone modified the `mvn.cmd`! Please compare/replace yours with the [(3.6.3) release version](https://github.com/apache/maven/blob/maven-3.6.3/apache-maven/src/bin/mvn.cmd) — xerx593, Feb 26 '21 at 16:07
@Gimby You were right. My colleague sent me an updated cmd file long ago, which I copied, and that had the JDK hard coded. I am not sure of the validity of the question anymore! — hell_storm2004, Mar 03 '21 at 12:21

Alexander Petrov · Answer 1 · 2021-02-24T14:09:03.443

2

You can use the element inside maven-compiler-plugin.

As described here How to tell compiler to use openjdk 11 via pom.xml Here is a bit more advanced example that allows you to compile Java 11 while your main java version is 8. Most of my projects are still java 8 so I find it usefull.

<plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.0</version>
            <configuration>
                <release>11</release>
                <fork>true</fork>
                <executable>C:\Program Files\Java\jdk-11.0.2\bin\javac</executable>
            </configuration>
        </plugin>

edited Feb 24 '21 at 14:09

answered Feb 24 '21 at 13:53

Alexander Petrov

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I dont mind doing this option. But i would like to have a little bit more permanent solution if that is possible. – hell_storm2004 Feb 24 '21 at 14:45
No matter if you configure or not configure. This plugin aways runs. – Alexander Petrov Feb 24 '21 at 15:12
`C:\Program Files\Java\jdk-11.0.2\bin\javac`. This. Its a shared codebase, so just dont want to hard code the java path in the pom file. – hell_storm2004 Feb 24 '21 at 15:12
This part is optional configuration. You can just remove it. – Alexander Petrov Feb 24 '21 at 15:13
I just added it because on a build server very often you have more than one jvm – Alexander Petrov Feb 24 '21 at 15:14
Same with – Alexander Petrov Feb 24 '21 at 15:15
Okay... Giving it a try without the path. – hell_storm2004 Feb 24 '21 at 15:20
That gives me something totally different `Caused by: java.lang.IllegalArgumentException: invalid flag: --release`. My compiler plugin is 3.8.1. – hell_storm2004 Feb 24 '21 at 15:24
Did you remove - fork ? Fork is only if you use own execute. – Alexander Petrov Feb 24 '21 at 15:33
Yes, I didn't even add it. – hell_storm2004 Feb 24 '21 at 15:37

score 0 · Answer 2 · answered Feb 26 '21 at 15:26

I use the toolchain mechanism of maven, works fine, you can switch easily of jdk compiler regarding which the project :

    <toolchains xmlns="http://maven.apache.org/TOOLCHAINS/1.1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
      xsi:schemaLocation="http://maven.apache.org/TOOLCHAINS/1.1.0 http://maven.apache.org/xsd/toolchains-1.1.0.xsd">
      <toolchain>
        <type>jdk</type>
        <provides>
          <version>1.8</version>
        </provides>
        <configuration>
          <jdkHome>your_java_8_local_path</jdkHome>
        </configuration>
      </toolchain>
      <toolchain>
        <type>jdk</type>
        <provides>
          <version>11</version>
        </provides>
        <configuration>
          <jdkHome>your_java_11_local_path</jdkHome>      
        </configuration>
      </toolchain>
    </toolchains>

Then just declare it in your pom.xml like this (compiling with jdk 11 by example here) :

<build>     
    <pluginManagement>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-toolchains-plugin</artifactId>
                <version>1.1</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>toolchain</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <toolchains>
                        <jdk>
                            <version>11</version>
                        </jdk>
                    </toolchains>
                </configuration>
            </plugin>
        </plugins>
    </pluginManagement>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-toolchains-plugin</artifactId>
            </plugin>
     </plugins>
</build>

Maven Not Using JDK 11

2 Answers2