Setting the Java Version in Maven with system Java version as 11.0

Question

I am currently using jdk version as 11 in my local machine, Set using JAVA_HOME.

I need to run a maven project with java_version as 9. for doing the same took reference from https://www.baeldung.com/maven-java-version

here is my pom.xml file

<properties>
    <java.version>8</java.version>
    <maven.compiler.plugin.version>3.8.0</maven.compiler.plugin.version>
</properties>
<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>${maven.compiler.plugin.version}</version>
            <configuration>
                <release>8</release>
            </configuration>
        </plugin>
    </plugins>
</build>

Then i ran the command "mvn clean install" and the jar file generated is having java-version as 11 in its manifest file. here is the snippet of Manifest file of the gemnerated jar

Manifest-Version: 1.0
Archiver-Version: Plexus Archiver
Created-By: Apache Maven 3.5.0
Built-By: test
Build-Jdk: 11.0.2

Why it is still picking java version as 11, why not 8?

You can perform `mvn -v` to check what version of Java is your Maven configured (`~/.mvnrc`) with. Also, note `release` as a flag would only be identified by Java-9 (value 9) and above. Besides which Java-8 is supposed to be `1.8` and not `8`. — Naman, Dec 20 '19 at 11:26
I am not sure whether you know this: The JDK with which you build and the Java version you build for can be different. It is perfectly possible to build _for_ Java 8 _with_ JDK 11. — J Fabian Meier, Dec 20 '19 at 11:55

Vishwa Ratna · Answer 1 · 2019-12-20T12:02:43.523

3

You can explicitly change the java version on the go for the particular project so that it gets compliled with the version you want.

Use : JAVA_HOME=/path/to/jdk1.8/ mvn build

Beside above you can explicitly set the version in your pom.

<properties>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>

edited Dec 20 '19 at 12:02

answered Dec 20 '19 at 11:52

Vishwa Ratna

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M A · Accepted Answer · 2019-12-20T12:07:40.027

3

Setting java.version in the POM <properties> section does not change the Java version used to compile with the maven-compiler-plugin. It is instead used by Spring Boot (see Specifying java version in maven - differences between properties and compiler plugin for a related discussion).

Your build is still using the JDK 11 installed on your machine (this is reflected by the manifest attribute Build-Jdk: 11.0.2), however, your code is actually compiled with source and target of Java 8. JDK 11 knows how to compile against earlier versions like JDK 8, so your build is working fine as expected.

edited Dec 20 '19 at 12:07

answered Dec 20 '19 at 12:00

M A

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Say you have jdk1.8 somewhere in your PC, then if you run `JAVA_HOME=/path/to/jdk1.8/ mvn build` then build will be from 1.8 – Vishwa Ratna Dec 20 '19 at 12:07
@VishwaRatna Yes, but you can still use JDK 11 to compile against 8, 9 or 10. No need to switch the JDK. – M A Dec 20 '19 at 12:08
Yeah,There is always a backward compatibility. – Vishwa Ratna Dec 20 '19 at 12:09

score 1 · Answer 3 · answered May 15 '22 at 11:08

1

set fist of all JAVA_HOME then execute the mvn clean install

export JAVA_HOME="C:/Program Files/Java/jdk-11.0.15"

Then excute maven commands

mvn clean install

Note: export command will not work on CMD use gitbash for this command.

answered May 15 '22 at 11:08

sajeeth

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2
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Setting the Java Version in Maven with system Java version as 11.0

3 Answers3