Install libautomaton-java by entering the following commands in the terminal:
sudo apt update sudo apt install libautomaton-java
Description:
Finite-State Automaton for Regular Expressions
Automaton is a DFA/NFA (finite-state automata) implementation with Unicode alphabet (UTF16) and support for the standard regular expression operations (concatenation, union, Kleene star) and a number of non-standard ones (intersection, complement, etc.).
Homepage: http://www.brics.dk/automaton/index.html
Version: 1.11-8+dfsg1-1
Section: universe/java