How do I run mutiple Java applications with different versions?

I am using Ubuntu 18.04 LTS and I have 2 apps which need to run with different Java versions. My 1st app (Mirth Connect) needs to run on jre1.8.0_171 and my second app (Power Assist) needs to run on java-11-openjdk-amd64.

$ sudo update-alternatives --config java
There are 3 choices for the alternative java (providing /usr/bin/java).
0 /usr/lib/jvm/java-11-openjdk-amd64/bin/java
1 /usr/lib/jvm/java-11-openjdk-amd64/bin/java
2 /usr/lib/jvm/jdk-16.0.2/bin/java
3 /usr/local/java/jre1.8.0_171/bin/java 

How do I make my 1st app to work with 3 and my 2nd app to work with 1?

$ sudo gedit /etc/profile
if [ "${PS1-}" ]; then if [ "${BASH-}" ] && [ "$BASH" != "/bin/sh" ]; then # The file bash.bashrc already sets the default PS1. # PS1='\h:\w\$ ' if [ -f /etc/bash.bashrc ]; then . /etc/bash.bashrc fi else if [ "`id -u`" -eq 0 ]; then PS1='# ' else PS1='$ ' fi fi
fi
if [ -d /etc/profile.d ]; then for i in /etc/profile.d/*.sh; do if [ -r $i ]; then . $i fi done unset i
fi
JAVA_HOME=/usr/local/java/jre1.8.0_171
PATH=$PATH:$HOME/bin:$JAVA_HOME/bin
export JAVA_HOME
export PATH

1 Answer

Your best bet would probably be to launch these applications from scripts, where you first change some of the environment variables.

export PATH=/usr/lib/jvm/java-11-openjdk-amd64/bin:$PATH
export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64

The first change causes the java executable at /usr/lib/jvm/java-11-openjdk-amd64/bin/ to be the one that is found when you launch java. The second change updates the JAVA_HOME environmental variable.