Vectors -please explain

Question

I'm looking through a textbook (Java How to program by Dietel abd Dietel) which provides some code to connect to database and then to display the database on the screen. However, I am trying to understand the code and can't understand the following methods.
From what i can see currentRow is a vector within a set of other vectors; rows. Am I right? Basically I just want to know how the vectors in this code extract work. Thanks.
private void displayResultSet(ResultSet rs)throws SQLException{
       boolean moreRecords = rs.next(); //position to first records
//       If there are no records, display a message
          if (! moreRecords){
               JOptionPane.showMessageDialog (this, "The specified table contains no"
                                                     + " records");
               setTitle ("No records to display");
               return;
          Vector columnHeads = new Vector ();
          Vector rows = new Vector();
          try{
//       get column heads
               ResultSetMetaData rsmd = rs.getMetaData();
               theCount = rsmd.getColumnCount();
               dist.setUp(theCount, theRowCount);
               for (int i = 1; i <= rsmd.getColumnCount(); ++i)
                    columnHeads.addElement(rsmd.getColumnName(i));
                    do{
                         rCount++;
                         rows.addElement(getNextRow(rs, rsmd));
                    } while (rs.next());
               JTable thetable = new JTable (rows, columnHeads);
               JScrollPane scroller = new JScrollPane(thetable);
                getContentPane().add(scroller, BorderLayout.CENTER);
               validate();
                 dist.doComparison(columnHeads, rows);
     catch (SQLException e){
       //display some message
  private Vector getNextRow(ResultSet rs, ResultSetMetaData rsmd)
       throws SQLException{
   Vector currentRow = new Vector();
     for (int i=1; i <= rsmd.getColumnCount(); ++i)
          switch (rsmd.getColumnType(i)){
               case Types.VARCHAR:currentRow.addElement(rs.getString(i));
                    break;
               case Types.INTEGER:currentRow.addElement(new Long (rs.getLong (i)));
                    break;
               default:
                    System.out.println("Type was: " + rsmd.getColumnTypeName (i));
     return currentRow;
  }

Answer 1

Did D&D tell you to put this code in?
     catch (SQLException e){
     //display some message
     }Terrible idea. At LEAST print the stack trace:
catch (Exception e)
    e.printStackTrace();
}An empty catch block is a great way to have a class that fails "mysteriously" with no feedback or info. You'll debug for a long time until you add that stack trace print.
I've heard that D&D puts out good books, but if they're recommending that you code this way I'd throw it out.
If you did that on your own, give yourself a d0pe slap and add the stack trace from now on. - MOD