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.
here is segment of my Java code:

DriverManager.registerDriver( new oracle.jdbc.driver.OracleDriver());
conn = DriverManager.getConnection"jdbcracle:thin:@xxx.xx.xx.xxx:
1521:ipoll", "IPOLLDBA", "ipolldba");

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