actually need to know what driver are you using.
oracle.jdbc.driver.OracleDriver
jdbc
racle:thin:@<machine IP>:<1521 or if other port>:SID
are you using the same driver or some other???
if this one we can use the SID of the database. no need to create a listener and a service. you can just delete your listener and service both. if its not used by some other app.
hope this helps.