Adding to a Collection using JDBC

Question

I'm trying to add to a Collection via JDBC but have had no luck with getting the ResultSet into the Collection and would be grateful for some pointers in the right direction in the while (rs.next()) block:
public void getMembers(BwGroup group) throws CalFacadeException {
     Class.forName("com.mysql.jdbc.Driver");
     String url = "jdbc:mysql://localhost/loginlist";
     Connection conn = null;
     Collection<BwPrincipal> ms = new TreeSet<BwPrincipal>();
      try {
         conn = DriverManager.getConnection(url, "user", "pword");
         PreparedStatement ps = conn.prepareStatement("SELECT * FROM list WHERE list='" + group +"'");
         ResultSet rs = ps.executeQuery();
            while (rs.next()) {
               BwPrincipal = new bp(rs.getString(1));
               ms = addAll(bp);
           group.setGroupMembers(ms);
           rs.close();
           ps.close();
           } catch (Exception e){
            e.printStackTrace();
           } finally {
         if (conn != null) {
        conn.close();
    }I'm getting errors regarding incompatible types for the BwPrincipal line and addAll being an unfound symbol (though I had thought that it was a method to add to Collections). If I try to call BwPrincipal as BwPrincipal bp = new bp(rs.getString(1)); then the addAll error disappears but the programme cannot see BwPrincipal as a class. I feel as if I'm going around in circles at the moment.

Answer 1

BaroqueThoughts wrote:
As you say, I'm trying to call something along the lines of
ms= rs.getString(1);but get an incompatible string back. The reading that I had done suggested addAll but I've probably misunderstood in trying to get this to work. If I try
ms.add(rs)then the compiler doesn't like the add method (add cannot be applied to java.sql.ResultSet)Well it can't. Why did you try that, though? To be honest, if you can't figure this out yet, JDBC is probably a step too far at the moment. Re-visit the basics, because you clearly don't understand them yet, and you'll struggle forever if you carry on down this path as-is