[java] Why Maven uses JDK 1.6 but my java -version is 1.7

I'm new to maven, and also to MacOS.

I have setup maven in my terminal, and when getting the version settings (using mvn -v) it seems it uses JDK 1.6, while I have JDK 1.7 installed. Is there anything wrong?

The commands I enter are these:

blues:helloworld Ninja$ java -version

java version "1.7.0_05"
Java(TM) SE Runtime Environment (build 1.7.0_05-b06)
Java HotSpot(TM) 64-Bit Server VM (build 23.1-b03, mixed mode)`

blues:helloworld Ninja$ mvn -v

Apache Maven 3.1.0 (893ca28a1da9d5f51ac03827af98bb730128f9f2; 2013-06-28 10:15:32+0800)
Maven home: /usr/local/Cellar/maven/3.1.0/libexec
Java version: 1.6.0_51, vendor: Apple Inc.
Java home: /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
Default locale: zh_CN, platform encoding: EUC_CN
OS name: "mac os x", version: "10.8.4", arch: "x86_64", family: "mac"

It helped me. Just add it in your pom.xml.

By default maven compiler plugin uses Java 1.5 or 1.6, you have to redefine it in your pom.xml.

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
            </configuration>
        </plugin>
    </plugins>
</build>

@MasterGaurav's solution works perfectly.

I normally put the Java switch statement into a zsh function:

alias java_ls='/usr/libexec/java_home -V 2>&1 | grep -E "\d.\d.\d[,_]" | cut -d , -f 1 | colrm 1 4 | grep -v Home'

function java_use() {
    export JAVA_HOME=$(/usr/libexec/java_home -v $1)
    echo export "JAVA_HOME=$(/usr/libexec/java_home -v $1)" > ~/.mavenrc
    export PATH=$JAVA_HOME/bin:$PATH
    java -version
}

You can run java_ls to get all of the available JVMs on your machine,
and then java_use 1.7 to use 1.7 for both Java and Maven.

You can also do,

<properties>
      ...  

      <!-- maven-compiler-plugin , aka JAVA Compiler 1.7 -->
      <maven.compiler.target>1.7</maven.compiler.target>
      <maven.compiler.source>1.7</maven.compiler.source>

      ...  
</properties>

Please check the compatibility. I struggled with mvn 3.2.1 and jdk 1.6.0_37 for many hours. All variables were set but was not working. Finally I upgraded jdk to 1.8.0_60 and mvn 3.3.3 and that worked. Environment Variables as following:

JAVA_HOME=C:\ProgramFiles\Java\jdk1.8.0_60 
MVN_HOME=C:\ProgramFiles\apache-maven\apache-maven-3.3.3 
M2=%MVN_HOME%\bin extend system level Path- ;%M2%;%JAVA_HOME%\bin;

Get into

/System/Library/Frameworks/JavaVM.framework/Versions

and update the CurrentJDK symbolic link to point to

/Library/Java/JavaVirtualMachines/YOUR_JDK_VERSION/Contents/

E.g.

cd /System/Library/Frameworks/JavaVM.framework/Versions
sudo rm CurrentJDK
sudo ln -s /Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/ CurrentJDK

Now it shall work immediately.

You can also explicitly tell maven which java version to compile for. You can try adding the maven-compiler-plugin to your pom.

<project>
  [...]
  <build>
    [...]
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.1</version>
        <configuration>
          <source>1.7</source>
          <target>1.7</target>
        </configuration>
      </plugin>
    </plugins>
    [...]
  </build>
  [...]
</project>

If you imported a maven project into an IDE, then there is probably a maven setting in your IDE for default compiler that your maven runner is using.

For Eclipse Users. If you have a Run Configuration that does clean package for example.

In the Run Configuration panel there is a JRE tab where you can specify against which runtime it should run. Note that this configuration overrides whatever is in the pom.xml.

I am late to this question, but I think the best way to handle JDK versions on MacOS is by using the script described at: http://www.jayway.com/2014/01/15/how-to-switch-jdk-version-on-mac-os-x-maverick/