You can use combination of 'ps' and 'grep' command to find any process running on UNIX machine. Suppose your Java process has a name or any text which you can use to match against just use following command.

ps -ef | grep "myJavaApp"

ps -e will list every process i.e. process from all user not just you and ps -f will give you full details including PID, which will be required if you want to investigate more or would like to kill this process using kill command.