Multiple Java versions management and switch on Mac OS X

For my research, I do need at least two different Java versions (6.0 and 7.0 or above) on my Mac OS X. I found this tool jEnv is very useful and the Andrew’s “ Managing multiple versions of Java on OS X” is helpful.

• Check Current Java Version

    $ java -version
    java version "1.6.0_65"
    Java(TM) SE Runtime Environment (build 1.6.0_65-b14-466.1-11M4716)
    Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-466.1, mixed mode)
    $ /usr/libexec/java_home
    /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
    $ ls /System/Library/Java/JavaVirtualMachines/
    1.6.0.jdk
  

Installation of jEnv

• Install

    $brew install jenv
  
    ==> Downloading https://homebrew.bintray.com/bottles/jenv-0.4.3.yosemite.bottle.tar.gz
    ######################################################################## 100.0%
    ==> Pouring jenv-0.4.3.yosemite.bottle.tar.gz
    ==> Caveats
    To enable shims and autocompletion add to your profile:
      if which jenv > /dev/null; then eval "$(jenv init -)"; fi
  
    To use Homebrew's directories rather than ~/.jenv add to your profile:
      export JENV_ROOT=/usr/local/opt/jenv
  
    ==> Summary
    🍺  /usr/local/Cellar/jenv/0.4.3: 74 files, 308K 
  

• Follow the instruction

    $ echo 'if which jenv > /dev/null; then eval "$(jenv init -)"; fi' >> .bash_profile
  

• Check

    $ jenv versions
    * system (set by /Users/ykf_2001/.jenv/version)
  

Installation of Java 8

• Download and install it manually from Oracle
• Check it

    $java -version
    java version "1.8.0_45"
    Java(TM) SE Runtime Environment (build 1.8.0_45-b14)
    Java HotSpot(TM) 64-Bit Server VM (build 25.45-b02, mixed mode)
    $ /usr/libexec/java_home
    /Library/Java/JavaVirtualMachines/jdk1.8.0_45.jdk/Contents/Home
    $ ls /Library/Java/JavaVirtualMachines/
    jdk1.8.0_45.jdk
  

• So now the OS comes with Java 8
• List all javas installed

    $ /usr/libexec/java_home -verbose
    Matching Java Virtual Machines (3):
        1.8.0_45, x86_64:    "Java SE 8"    /Library/Java/JavaVirtualMachines/jdk1.8.0_45.jdk/Contents/Home
        1.6.0_65-b14-466.1, x86_64:    "Java SE 6"    /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
  

Add of old Java 6 and Java 8 to jEnv

    $ jenv add /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
    oracle64-1.6.0.65 added
    1.6.0.65 added
    1.6 added
    $ jenv versions
    * system (set by /Users/ykf_2001/.jenv/version)
      1.6
      1.6.0.65
      oracle64-1.6.0.65
    $ jenv add /Library/Java/JavaVirtualMachines/jdk1.8.0_45.jdk/Contents/Home/
    oracle64-1.8.0.45 added
    1.8.0.45 added
    1.8 added
    $ jenv versions
    * system (set by /Users/ykf_2001/.jenv/version)
      1.6
      1.6.0.65
      1.8
      1.8.0.45
      oracle64-1.6.0.65
      oracle64-1.8.0.45

Configurations

• Set global Java version to Java 8

    $ jenv global oracle64-1.6.0.65
    $ jenv versions
      system
      1.6
      1.6.0.65
      1.8
      1.8.0.45
    * oracle64-1.6.0.65 (set by /Users/ykf_2001/.jenv/version)
      oracle64-1.8.0.45
    $ jenv global oracle64-1.8.0.45
    $ jenv versions
      system
      1.6
      1.6.0.65
      1.8
      1.8.0.45
      oracle64-1.6.0.65
    * oracle64-1.8.0.45 (set by /Users/ykf_2001/.jenv/version)
    $ cat ~/.jenv/version
    oracle64-1.8.0.45
    $ java -version
    java version "1.8.0_45"
    Java(TM) SE Runtime Environment (build 1.8.0_45-b14)
    Java HotSpot(TM) 64-Bit Server VM (build 25.45-b02, mixed mode)
  

• Set the Java 6 for local directories

    ~/Programs/eclipse-kepler-for-czt$ jenv local oracle64-1.6.0.65
    ~/Programs/eclipse-kepler-for-czt$ jenv versions
      system
      1.6
      1.6.0.65
      1.8
      1.8.0.45
    * oracle64-1.6.0.65 (set by /Users/ykf_2001/Programs/eclipse-kepler-for-czt/.java-version)
      oracle64-1.8.0.45
    ~/Programs/eclipse-kepler-for-czt$ cd ~/Workspace/czt-code-20150622/
    ~/Workspace/czt-code-20150622$ jenv local oracle64-1.6.0.65
    ~/Workspace/czt-code-20150622$ jenv versions
      system
      1.6
      1.6.0.65
      1.8
      1.8.0.45
    * oracle64-1.6.0.65 (set by /Users/ykf_2001/Workspace/czt-code-20150622/.java-version)
      oracle64-1.8.0.45
  

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