jdbc connectint ot db

I'm having trouble with connecting to db. I created user and password by
creatuser and pg_passwd, and have line in my pg_hba.conf

#####
local        all                                           password passwd
host         all         127.0.0.1     255.255.255.255     password passwd
#####

passwd is file create to have password.
now when i try to connect to db by 

#####
DriverManager.getConnection("jdbc:postgresql:test",user,pass);
#####

I get the following error messg,

#####
The backend has broken the connection. Possibly the action you have
attempted has caused it to close.
#####

i don't know what is causing to get this error anyone have any idea?

katsu