Connection timeout when connecting to a remote postgresql database

I am facing this problem: I have a program that loops the following:

• connect to a postgresql database
• print a count number
• close the connection

code is as follow:

int i = 0;
    while(true){

        IConnection conn = ((ConnectionHelper)HelperFactory.getInstance().getHelper("ConnectionHelper")).getConnection("psql");

        if(conn != null && conn.connect()){
            conn.close();
            System.out.println(i++);
        }
    }

I connect to psql db by jdbc, something like this:

DriverManager.getConnection("jdbc:postgresql://" + host + ":5432/" + database, 
                                            user, password);

the conn.connect() returns true if it can successfully connect to the database (tested, I can retrieve data from it)

But i get the following result:

0 1 2 . . . 3919 3920 3921 3922

org.postgresql.util.PSQLException: Connection refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.
    at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:136)
    at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:66)
    at org.postgresql.jdbc2.AbstractJdbc2Connection.<init>(AbstractJdbc2Connection.java:125)
    at org.postgresql.jdbc3.AbstractJdbc3Connection.<init>(AbstractJdbc3Connection.java:30)
    at org.postgresql.jdbc3g.AbstractJdbc3gConnection.<init>(AbstractJdbc3gConnection.java:22)
    at org.postgresql.jdbc4.AbstractJdbc4Connection.<init>(AbstractJdbc4Connection.java:30)
    at org.postgresql.jdbc4.Jdbc4Connection.<init>(Jdbc4Connection.java:24)
    at org.postgresql.Driver.makeConnection(Driver.java:393)
    at org.postgresql.Driver.connect(Driver.java:267)

at the last loop the program stuck at trying to connect to psql til timeout. Any help?