Comment 17 for bug 1720670

Hello sinus_asperitatis

Freeplane should run fine with Java8, and it requires either the default-jre package or package provided by openjdk-8-jre (https://packages.ubuntu.com/artful-updates/freeplane). Have you by any chance had Java7 installed at some point, but then removed it? Based on the output it looks like the system has been configured to use Java7, but that it is no longer in place.

Could you please attach the output of the following two commands:
apt policy openjdk-*-jre*
ls -la /etc/alternatives/java
This will tell us which Java (jre) packages you have installed, as well as which one the system will try to use when running java.