problem connecting to jdbc

Hello i have the following java code

public class BD
{
Connection db; // The connection to the database
Statement st; // Our statement to run queries with

public BD()
{

}

public Connection getConexion(String url, String usr, String pwd)
{
try{
Class.forName("org.postgresql.Driver");
}catch(ClassNotFoundException e)
{
System.out.print("1"+e);
}

try{
db = DriverManager.getConnection(url, usr, pwd);
}catch(SQLException e)
{
System.out.print("2"+e);
}
return db;

}
}

and i have the following class that uses BD.class

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;

import ConectarBd.BD;

public class Prueba {
public static void main(String[] argv) throws Exception
{
BD conectar=new BD();

Connection con =
conectar.getConexion("jdbc:postgresql://localhost/","lina","hello");

//Statement stm =
con.createStatement();
// ResultSet rs =
stm.executeQuery("select * from datosclinicos");

}
}

and the both compile with no problem but when i excecute the class Prueba
i get the following:

[root(at)lmgh Herramientas]# java Prueba
2The connection attempt failed because Exception: java.io.IOException:
Connection refused
Stack Trace:

java.io.IOException: Connection refused
at
java.net.PlainSocketImpl.socketConnect(PlainSocketImpl.java:native)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:57)
at java.net.Socket.<init>(Socket.java:54)
at java.net.Socket.<init>(Socket.java:29)
at org.postgresql.PG_Stream.<init>(PG_Stream.java:38)
at
org.postgresql.jdbc1.AbstractJdbc1Connection.openConnection(AbstractJdbc1Connection.java:160)
at org.postgresql.Driver.connect(Driver.java:122)
at java.sql.DriverManager.getConnection(DriverManager.java:63)
at java.sql.DriverManager.getConnection(DriverManager.java:51)
at ConectarBd.BD.getConexion(BD.java:42)
at Prueba.main(Prueba.java:13)
End of Stack Trace

PLEASE HELP ME ..what am i doing wrong??

--
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| | (_)_ _ __ _ | \/ | / __| | || | *
| |__| | ' \/ _` | | |\/| |_ | (_ |_| __ |_ *
|____|_|_||_\__,_| |_| |_(_) \___(_)_||_(_) *
Lina Maria Garcia Henao *
ESTUDIANTE DE INGENIERIA DE SISTEMAS *
limagarc(at)yahoo(dot)com *
Universidad Del Valle *
************************************************