connection refused

SQLException: Io exception: Connection refused(DESCRIPTION=(TMP=)(VSNNUM=153092352)(ERR=1 2505)(ERROR_STACK=(ERROR=(CODE=12505)(EMFI=4))))

This is the error message when I connect to DB using Java program.
SQLException: Io exception: Connection refused(DESCRIPTION=(TMP=)(VSNNUM=153092352)(ERR=1 2505)(ERROR_STACK=(ERROR=(CODE=12505)(EMFI=4))))

here is segment of my Java code:

DriverManager.registerDriver( new oracle.jdbc.driver.OracleDriver());
conn = DriverManager.getConnection"jdbcracle:thin:@xxx.xx.xx.xxx:
1521:sid", "username", "password");

Anyone can help me to fix it? Any more information needed, please email me. I will reply you within one day.
Thanks a lot!

ORA-12505

Cause: The SID in the CONNECT_DATA was not found in the listener's tables.

Action: Check to make sure that the SID specified is correct.
The SIDs that are currently registered with the listener can be obtained by typing supported can
be obtained by typing "LSNRCTL SERVICES listener_name".
These SIDs correspond to SID_NAMEs in TNSNAMES.ORA or db_names in INIT.ORA. Comment:
This error will be returned if the database instance has not registered with the listener;
the instance may need to be started.

thanks