Find and kill a process using a given port

I was trying to use Tabula to extract data from a pdf, but the program would't run correctly because the port it expected to use was already assigned to another program.

An answer on Stack Overflow taught me that two commands are needed to identify and kill the process on Mac:

sudo lsof -i tcp:8080

kill -15 PID

The first command gives the process ID for the program using localhost:8080, and the second command gives a kill signal to the process (substituting PID for the actual ID number given by the first command.)