No Postgres username specified in packet

First crack at using postgres. I'll take whatever suggestions you can
pass on. Running under Linux/Redhat. Has anybody seen this error? Checked
to see if -i was there, checked classpath to point to the .jar files.
Is this a "normal" error? Doesn't seem like it's getting past the driver
call.



$java sample  
Exception caught. 
Something unusual has occured to cause the driver to fail. Please report
this exception: java.sql.SQLException: No Postgres username specified in
startup packet.
Something unusual has occured to cause the driver to fail. Please report
this exception: java.sql.SQLException: No Postgres username specified in
startup packet.
at org.postgresql.Driver.connect(Driver.java:125)
at java.sql.DriverManager.getConnection(DriverManager.java:453)
at java.sql.DriverManager.getConnection(DriverManager.java:133)
at sample.<init>(sample.java:18)
at sample.main(sample.java:47)


import java.io.*;
import java.sql.*;


public class sample
{

Connection conn;
Statement stmt;
String state_code;

public sample() throws ClassNotFoundException, FileNotFoundException,
IOException, SQLException

{
Class.forName("org.postgresql.Driver");System.err.println("made it this far");System.out.println("made it this far");
conn =
DriverManager.getConnection("jdbc:postgresql://127.0.0.1/testdb","testuser","");stmt = conn.createStatement();
System.out.print("Enter a state code: ");System.out.flush();BufferedReader r = new BufferedReader(new
InputStreamReader(System.in));state_code = r.readLine();
ResultSet res = stmt.executeQuery(        "Select name " +        "From statename " +        "Where code = '" +
state_code+ "'");
 
if (res !=null)    while(res.next())    {    String state_name = res.getString(1);    System.out.println(state_name);
}
 
    res.close();    stmt.close();    conn.close();
}

public static void main(String args[])
{
try{    sample testdb = new sample();   }catch(Exception exc)   {       System.err.println("Exception caught. \n" +
exc);   exc.printStackTrace();   }   
 
}


}