Install HomeBrew first
```sh
brew update
brew tap caskroom/cask
brew install brew-cask
```
If you get the error "already installed", follow the instructions to unlink it, then install again:
```sh
brew unlink brew-cask
brew install brew-cask
```
upgrade brew:
```brew update && brew upgrade brew-cask && brew cleanup && brew cask cleanup```
Install Java 7 and 8
People on the Stackoverflow cautioned not to install 8 until 7 is installed. So we are going to install JDK 7 first.
Unlike other version managers such as NVM, jEnv itself doesn’t install JDKs. You have to do it yourself. Luckily, Homebrew Cask made this task really easy. But before doing that, let’s check if we already have JDK 7 installed by Homebrew Cask:
```sh
brew tap caskroom/versions
brew cask info java7
```
install Java 7:
```brew cask install java7```
If you run into permission issue, add sudo at the beginning of the above command.
As of today, Java 8 is the latest stable. Run the following command to install Java 8:
```brew cask install java```
These two JDKs will be installed at the following directories. Your JDKs’ minor and patch versions might be different.
```
/Library/Java/JavaVirtualMachines/jdk1.7.0_79.jdk/Contents/Home/
/Library/Java/JavaVirtualMachines/jdk1.8.0_66.jdk/Contents/Home/
```
Enter jEnv
Now it is time to install jEnv:
```brew install jenv```
Add the following lines to ~/.bash_profile. This will initialize jEnv.
```
# Init jenv
if which jenv > /dev/null; then eval "$(jenv init -)"; fi
```
jEnv doesn’t install JDKs, so we have to tell jEnv where to look for them. Type these commands to register JDKs in jEnv (replace the minor and patch versions with yours):
```sh
jenv add /Library/Java/JavaVirtualMachines/jdk1.7.0_79.jdk/Contents/Home/
jenv add /Library/Java/JavaVirtualMachines/jdk1.8.0_66.jdk/Contents/Home/
```
After that, run this command to list all registered JDKs:
```jenv versions```
The version with an asterisk is the active version.
In my case, I need to keep JDK 7 as my default version, so I set the global version to 1.7:
```jenv global oracle64-1.7.0.79```
And in my project, I set the local JDK version to 1.8:
```sh
cd <my project>
jenv local oracle64-1.8.0.66
```
The above command will create a .java-version file at project root. Its content is the version I just picked for this project:
```oracle64-1.8.0.66```