My machine is ipv6 compatible.When i try to connect to postgres which is on my local machine by giving the URL like "jdbc:postgresql://[:]/sigaba_admin,user name,password" it is giving me the exception

org.postgresql.util.PSQLException: Connection refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.
Exception: java.net.ConnectException: Connection refused: connect.

while when i used ipv4 ip like jdbc:postgresql://127.0.0.1/sigaba_admin,user name,password it is working perfectly.I have postgres jar version 8.0.Please suggest