If you are using Sams Release like me then you’ll probably have installed it in your home directory
/home/tux/processing4
The actual processing will be in
/home/tux/processing4/work and the java folder will be
/home/tux/processing4/work/java
Delete or move that folder and replace with symbolic link as described. Once created you should be able to
ls -al in a terminal in the work directory:-
java -> /usr/lib/jvm/java-14-openjdk
or java -> /usr/lib/jvm/default-runtime where default-runtime is itself a symbolic link.