Mac OS X and multiple Java versions

Question

How can I install an additional java on MacOS? I installed jdk8 and that works fine. But now I need a jdk7 installation for development purposes. When trying to install the old version via DMG file, i get a warning, that there is already a newer version of java installed and the installer quits.

    /usr/libexec/java_home -verbose     Matching Java Virtual Machines (1):         1.8.0_20, x86_64:   "Java SE 8" /Library/Java/JavaVirtualMachines/jdk1.8.0_20.jdk/Contents/Home         /Library/Java/JavaVirtualMachines/jdk1.8.0_20.jdk/Contents/Home 

How to install jdk7 in addition to this one?

Answer 1

The cleanest way to manage multiple java versions on Mac is to use Homebrew.

And within Homebrew, use:

• homebrew-cask to install the versions of java
• jenv to manage the installed versions of java

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As seen on http://hanxue-it.blogspot.ch/2014/05/installing-java-8-managing-multiple.html , these are the steps to follow.

1. install homebrew
2. install homebrew jenv
3. install homebrew-cask
4. install a specific java version using cask (see "homebrew-cask versions" paragraph below)
5. add this version for jenv to manage it
6. check the version is correctly managed by jenv
7. repeat steps 4 to 6 for each version of java you need

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homebrew-cask versions

Add the homebrew/cask-versions tap to homebrew using:

brew tap homebrew/cask-versions 

Then you can look at all the versions available:

brew search java 

Then you can install the version(s) you like:

brew cask install java7 brew cask install java6 

And add them to be managed by jenv as usual.

jenv add <javaVersionPathHere> 

I think this is the cleanest & simplest way to go about it.

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Another important thing to note, as mentioned in Mac OS X 10.6.7 Java Path Current JDK confusing :

For different types of JDKs or installations, you will have different paths

You can check the paths of the versions installed using /usr/libexec/java_home -V, see How do I check if the Java JDK is installed on Mac?

On Mac OS X Mavericks, I found as following:

1) Built-in JRE default: /Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin/Contents/Home

2) JDKs downloaded from Apple: /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home/

3) JDKs downloaded from Oracle: /Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home

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Resources

• Removing Java 8 JDK from Mac
• http://hanxue-it.blogspot.ch/2014/05/installing-java-8-managing-multiple.html
• http://sourabhbajaj.com/mac-setup/index.html
• http://brew.sh
• https://github.com/Homebrew/homebrew/tree/master/share/doc/homebrew#readme
• http://sourabhbajaj.com/mac-setup/Homebrew/README.html
• "brew tap” explained https://github.com/Homebrew/homebrew/blob/master/share/doc/homebrew/brew-tap.md
• “brew versions” explained Homebrew install specific version of formula? and also https://github.com/Homebrew/homebrew-versions
• https://github.com/caskroom/homebrew-cask
• “cask versions”, similar to “brew versions”, see https://github.com/caskroom/homebrew-versions and also https://github.com/caskroom/homebrew-cask/issues/9447
• http://www.jenv.be
• https://github.com/gcuisinier/jenv

Answer 2

Uninstall jdk8, install jdk7, then reinstall jdk8.

My approach to switching between them (in .profile) :

export JAVA_7_HOME=$(/usr/libexec/java_home -v1.7) export JAVA_8_HOME=$(/usr/libexec/java_home -v1.8) export JAVA_9_HOME=$(/usr/libexec/java_home -v9)  alias java7='export JAVA_HOME=$JAVA_7_HOME' alias java8='export JAVA_HOME=$JAVA_8_HOME' alias java9='export JAVA_HOME=$JAVA_9_HOME'  #default java8 export JAVA_HOME=$JAVA_8_HOME 

Then you can simply type java7 or java8 in a terminal to switch versions.

(edit: updated to add Dylans improvement for Java 9)