How to set specific java version to Maven

Question

On my machine I have two java versions installed: (1.6 and 1.7 installed manually by me). I need both of them for different projects. But for Maven I need 1.7, now my Maven uses 1,6 java version, how can I set Maven to use 1.7?

Answer 1

Maven uses the JAVA_HOME parameter to find which Java version it is supposed to run. I see from your comment that you can't change that in the configuration.

• You can set the JAVA_HOME parameter just before you start maven (and change it back afterwards if need be).
• You could also go into your mvn(non-windows)/mvn.bat/mvn.cmd(windows) and set your java version explicitly there.

Answer 2

To avoid any impact to your project and to your Environment Variables, you can configure the Maven Compiler Plugin just to the project's POM, specifying the Source and Target java version

  <plugins>
    <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.5.1</version>
        <configuration>
            <source>1.7</source>
            <target>1.7</target>
        </configuration>
    </plugin>
    ...
  </plugins>

Answer 3

One simple solution to the problem -

JAVA_HOME=/usr/lib/jvm/java-6-sun/ mvn clean install

On Mac, it would look something like -

JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.7.0_21.jdk/Contents/Home/ mvn clean install

PS: One special case that i found is the above given command does not work on 'fish' shell. I also had bash shell available and it worked fine there. just use command 'bash' to switch to bash shell.

Answer 4

On windows

If you do not want to change your JAVA_HOME variable inside the system variables.

Edit your mvn.bat file and add a line like this

set JAVA_HOME=C:\Program Files\Java\jdk1.7.0_45\jre

This can be done after @REM ==== START VALIDATION ==== like mentionned by @Jonathan

On Mac (& Linux ?)

If you do not want to change your JAVA_HOME variable inside your ~/.bashrc or ~/.bash_profile

you can create a ~/.mavenrc file and redefine your JAVA_HOME using the java_home tool

export JAVA_HOME=`/usr/libexec/java_home -v 1.7.0_45`

Sanity Check

You can verify that everything is working fine by executing the following commands. The jdk version should be different.

mvn -version

then

java -version

Answer 5

Also you can have two versions of maven installed, and edit one of them, editing here:

mvn(non-windows)/mvn.bat/mvn.cmd(windows)

replacing your %java_home% appearances to your java desired path. Then just execute maven from that modified path

Answer 6

Without changing Environment Variables, You can manage java version based on the project level by using Maven Compiler Plugin.

Method 1

<properties>
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
</properties>
<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

Method 2

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
                <source>1.7</source>
                <target>1.7</target>
            </configuration>
        </plugin>
    </plugins>
</build>