Htykuut

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)

For macOS Sierra 420

This guide was cobbled together from various sources (replies above as well as other posts), and works perfect.

0. If you haven't already, install homebrew.

See https://brew.sh/

1. Install jenv

brew install jenv

2. Add jenv to the bash profile

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

3. Add jenv to your path

export PATH="$HOME/.jenv/shims:$PATH"

4. Tap "caskroom/versions"

FYI: "Tap" extends brew's list of available repos it can install, above and beyond brew's default list of available repos.

brew tap caskroom/versions

5. Install the latest version of java

brew cask install java

6. Install java 6 (or 7 or 8 whatever you need)

brew cask install java6

#brew cask install java7

#brew cask install java8

? Maybe close and restart Terminal so it sees any new ENV vars that got setup.

7. Review Installations

All Java version get installed here: /Library/Java/JavaVirtualMachines lets take a look.

ls -la /Library/Java/JavaVirtualMachines

8. Add each path to jenv one-at-a-time.

We need to add "/Contents/Home" to the version folder.
WARNING: Use the actual paths on your machine... these are just EXAMPLE's

jenv add /Library/Java/JavaVirtualMachines/1.6.0___EXAMPLE___/Contents/Home

jenv add /Library/Java/JavaVirtualMachines/jdk-9.0.1.jdk___EXAMPLE___/Contents/Home

9. Check if jenv registered OK

jenv versions

10. Set java version to use (globably)

Where XX matches one of the items in the versions list above.

jenv global XX

Check java version

java -version

Check jenv versions

Should also indicate the current version being used with an asterisk.

jenv versions

DONE

Quick future reference

To change java versions

... See the list of available java versions

jenv versions

... then, where XX matches an item in the list above

jenv global XX

SDKMAN! is a great tool for using multiple versions of Java, Gradle, Groovy, Kotlin, and other JVM tools on Mac OS. Installation and usage doc are plainly on the main site.

(I have no affiliation, just a happy user).

As an example usage, if I type the following in a Terminal window, there is a list of available Java SDK versions (edited for brevity):

$ sdk list java

Available Java Versions

   + 9ea170                                                                        

 > + 8u131                                                                         

     7u141-zulu                     

Here + denotes that the version is installed. > denotes which version is currently in use. To install a version:

$ sdk install java 7u141-zulu

To use a version in this Terminal window:

$ sdk use java 9ea170

As found on this website
So Let’s begin by installing jEnv

1. 
   

   Run this in the terminal

   
   
   

   brew install https://raw.github.com/gcuisinier/jenv/homebrew/jenv.rb
   
   

   
   


2. 
   

   Add jEnv to the bash profile

   
   
   

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

   
   


3. 
   

   When you first install jEnv will not have any JDK associated with it.

   
   
   

   For example, I just installed JDK 8 but jEnv does not know about it. To check Java versions on jEnv

   
   
   

   At the moment it only found Java version(jre) on the system. The * shows the version currently selected. Unlike rvm and rbenv, jEnv cannot install JDK for you. You need to install JDK manually from Oracle website.

   
   



4. Install JDK 6 from Apple website. This will install Java in /System/Library/Java/JavaVirtualMachines/. The reason we are installing Java 6 from Apple website is that SUN did not come up with JDK 6 for MAC, so Apple created/modified its own deployment version.




5. Similarly install JDK7 and JDK8.



6. 
   

   Add JDKs to jEnv.

   
   
   

   JDK 6:

   
   
   

   JDK 7:
   

   
   
   

   JDK 8:
   

   
   


7. 
   

   Check the java versions installed using jenv

   
   
   

   

   
   


8. 
   

   So now we have 3 versions of Java on our system. To set a default version use the command

   
   
   

   jenv local <jenv version>
   
   

   
   
   

   Ex – I wanted Jdk 1.6 to start IntelliJ

   
   
   

   jenv local oracle64-1.6.0.65
   
   

   
   


9. 
   

   check the java version

   
   
   

   java -version
   

   
   

That’s it. We now have multiple versions of java and we can switch between them easily. jEnv also has some other features, such as wrappers for Gradle, Ant, Maven, etc, and the ability to set JVM options globally or locally. Check out the documentation for more information.

I find this Java version manager called Jabba recently and the usage is very similar to version managers of other languages like rvm(ruby), nvm(node), pyenv(python), etc. Also it's cross platform so definitely it can be used on Mac.

After installation, it will create a dir in ~/.jabba to put all the Java versions you install. It "Supports installation of Oracle JDK (default) / Server JRE, Zulu OpenJDK (since 0.3.0), IBM SDK, Java Technology Edition (since 0.6.0) and from custom URLs.".

Basic usage is listed on their Github. A quick summary to start:

curl -sL https://github.com/shyiko/jabba/raw/master/install.sh | bash && . ~/.jabba/jabba.sh



# install Oracle JDK

jabba install 1.8 # "jabba use 1.8" will be called automatically  

jabba install 1.7 # "jabba use 1.7" will be called automatically 



# list all installed JDK's

jabba ls



# switch to a different version of JDK

jabba use 1.8

I am using Mac OS X 10.9.5. This is how I manage multiple JDK/JRE on my machine when I need one version to run application A and use another version for application B.

I created the following script after getting some help online.

#!bin/sh

function setjdk() {

  if [ $# -ne 0 ]; then

   removeFromPath '/Library/Java/JavaVirtualMachines/'

   if [ -n "${JAVA_HOME+x}" ]; then

    removeFromPath $JAVA_HOME

   fi

   export JAVA_HOME=/Library/Java/JavaVirtualMachines/$1/Contents/Home

   export PATH=$JAVA_HOME/bin:$PATH

  fi

 }

 function removeFromPath() {

  export PATH=$(echo $PATH | sed -E -e "s;:$1;;" -e "s;$1:?;;")

 }

#setjdk jdk1.8.0_60.jdk

setjdk jdk1.7.0_15.jdk

I put the above script in .profile file. Just open terminal, type vi .profile, append the script with the above snippet and save it. Once your out type source .profile, this will run your profile script without you having to restart the terminal. Now type java -version it should show 1.7 as your current version. If you intend to change it to 1.8 then comment the line setjdk jdk1.7.0_15.jdk and uncomment the line setjdk jdk1.8.0_60.jdk. Save the script and run it again with source command. I use this mechanism to manage multiple versions of JDK/JRE when I have to compile 2 different Maven projects which need different java versions.

Jenv on Mac Sierra:

if not working after install, do this bug fix to add java executable to path

export PATH="$HOME/.jenv/shims:$PATH"

even though eval "$(jenv init -)" could do this job. The reason is /bin folder is not there anymore as describe in it's homepage, but shim folder is used as /bin instead.

• Make sure ~/.jenv is there


• 
  which java may print /Library/...


• jenv global 1.8


• jenv shell 1.8

Eventually, which java gives you:

/Users/xxxx/.jenv/shims/java

Here's a more DRY version for bash (Based on Vegard's answer)

Replace 1.7 and 1.8 with whatever versions you are interested with
and you'll get an alias called 'javaX'; where 'X' is the java version (7 / 8 in the snippet below) that will allow you to easily switch versions

for version in 1.7 1.8; do

    v="${version: -1}"

    h=JAVA_"$v"_HOME



    export "$h"=$(/usr/libexec/java_home -v $version)



    alias "java$v"="export JAVA_HOME=$$h"

done