Java Oracle localhost anslutningsfel (ORA-12505)

Kontrollera om filen listener.ora under <ORACLE_HOME>\admin\NETWORK katalogen har följande värde:

XE =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = XE)
    )
  )