Tomcat won't start - how to check that port 8080 is not in use
Open up a command prompt and run
netstat -ano | findstr 8080
Rightmost column is PID
In task manager you can add column for PID then find the app that is using the port.
I think you can run cmd as administrator and use netstat command to see if port 8080 is being used. Use netstat /? for help with netstat command. I do not know any GUI based approach for the same.
In addition to netstat you can also use Process Hacker or ActivePorts to view open ports in real-time (ok, specific refresh intervals...)