From the command line, run:
$jps
To get a list of all of the running Java processes and use kill p# to kill each of the processes you no longer want running.
$kill p#

Technical notes, and other ideas.
From the command line, run:
$jps
To get a list of all of the running Java processes and use kill p# to kill each of the processes you no longer want running.
$kill p#