When compiling on Ubuntu 20.04 I get this error when I try to compile

Task :compileJava FAILED
/home/owner/Desktop/RDSSurvey/RdsSurveyor-master/RDSSurveyor/src/eu/jacquet80/rds/ui/MainWindow.java:409: error: local variable stationTuned is accessed from within inner class; needs to be declared final
station = stationTuned.getStation();