Testing in Space

As a nerd, I always tend to use the latest technologies and try them out in experimental ways, but I never wanted to do that with the old ones. I installed recently one media application which required Java 6.

Java 6? Huh, that’s like 2006.

Alright, I needed to keep Java 8 for all my other projects while also having Java 6 for non work related things.

A solution that allows this is to use jEnv.

jEnv is a simple command line tool that allows you to manage multiple Java versions. I will assume you have Homebrew already on your Mac.

Install jEnv via Homebrew:

brew update 
brew install jenv

To make jEnv available from anywhere in your PATH, you should add following to .bash_profile :

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

Now, that you have jEnv, we can check what Java versions are installed:

$ jenv versions
 system
 1.8
* oracle64-1.8.0.131 (set by /Users/user/.java-version)

We can see that it detected the system Java and 1.8. The Asterisk in front of the system version marks the current selection.

You can’t install any version of Java with jEnv, so we need to do it other way.

Initially I needed Java 6, which I downloaded from Apple.

Installation goes to:

/System/Library/Java/JavaVirtualMachines/

We can add it to jEnv:

jenv add /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home/

Now, if you check versions again:

$ jenv versions
system
  1.6
  1.6.0.65
  1.8
  1.8.0.131
  oracle64-1.6.0.65
* oracle64-1.8.0.131 (set by /Users/user/.java-version)

Ok, so far I am happy.

In case you need Java 7, you can install it from Oracle.

It is installed in:

/Library/Java/JavaVirtualMachines/

And add it to jEnv:

jenv add /Library/Java/JavaVirtualMachines/jdk1.7.0_67.jdk/Contents/Home/

I have Java 8, as you could see, but if you do not, you can install it from Oracle.

And, add it to jEnv:

jenv add /Library/Java/JavaVirtualMachines/jdk1.8.0_131.jdk/Contents/Home/

Java 7 and 8 you can also install using Homebrew Cask:

If you don’t have Homebrew Cask installed, you can easily do that:

brew update
brew tap caskroom/cask
brew install brew-cask

Now, let’s check if there is already java 7:

brew tap caskroom/versions
brew cask info java7

Now that we have all versions installed and added to jEnv, we just need to select them.

jEnv helps there.

To select a specific version we run:

jenv local [version]

For example:

jenv local oracle64-1.6.0.65

If we check what is the selected Java version:

$ java -version
java version "1.6.0_65"
Java(TM) SE Runtime Environment (build 1.6.0_65-b14-462-11M4609)
Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-462, mixed mode)

jEnv comes with some more handy commands. You can select a default version with:

jenv global [version]

You can also set a version of Java to certain directories by creating a file .java-version with content of the version, for instance, oracle64-1.6.0.65. jEnv will make sure to use that local version when you change to this directory.