On my machine (GNU/Linux Arch distribution) I’m usually running the latest version of the JDK (at the moment of writing this post JDK 1.8.0_60 (build 1.8.0_60-b27).
Till now, I had a small script “/etc/profile.d/java-env.sh” which was defining the JAVA_HOME parameter and when I need to use a different version of the JDK i would just open the terminal edit the file, reload the profile and start the Java app.

The contents of “/etc/profile.d/java-env.sh” were:

#$ export JAVA_HOME=<PATH_TO_THE_JAVA_7_INSTALLATION>
$ export JAVA_HOME=<PATH_TO_THE_JAVA_8_INSTALLATION>
$ export PATH=$PATH:$JAVA_HOME/bin

I was doing this for a while… I was a bit lazy to find a better solution, but I wanted to save myself from doing this over and over again. Recently I did a fresh install of my GNU/Linux so I thought it was time to fix this problem too.
When I was searching for a solution for this problem I came across this answer on Stack Exchange. The answer was good enough, but I didn’t want to write the whole path to the Java installation so I edited it this way:

#!/bin/bash
case "$1" in
   7)
       JAVA_HOME=<PATH_TO_THE_JAVA_7_INSTALLATION>
       ;;
   8)
       JAVA_HOME=<PATH_TO_THE_JAVA_8_INSTALLATION>
       ;;
   *)
       JAVA_HOME=$1
esac

export JAVA_HOME; shift
PATH=${JAVA_HOME}/bin:$PATH
$*

I named this script “javawrapper.sh”. To test if it works try executing the following commands in the terminal

$ ./javawrapper.sh 7 <APPLICATION_TO_START>
$ ./javawrapper.sh 7 java -version
$ ./javawrapper.sh 8 java -version

You will see the version of your Java 7 or 8

Someone my ask why does this work because after the second JAVA_HOME we have two java versions defined in our PATH. It works because we are adding the new, temporal JAVA_HOME at beginning of the PATH variable and when the GNU/Linux operating system processes the PATH variable value the first java executable that will be found and executed is in our newly added JAVA_HOME path.

After adding this script my “/etc/profile.d/java-env.sh” looks like this:

$ export JAVA_HOME=<PATH_TO_THE_JAVA_8_INSTALLATION>
$ export PATH=$PATH:$JAVA_HOME/bin

I hope this helps and I would like to hear how did the other solve this problem. Just one more quick note for the Debian users who will probably suggest using “update-alternatives”: there is no such thing in Arch Linix.

Happy hacking