How to do black and white box testings of this part of code?

public class DailyMovementsRecords extends javax.swing.JFrame {

Connection conn; 
Statement stmt; 
PreparedStatement pst;
public void reloaded() {
           try {
           stmt = CreateDB.getConnection().createStatement();
    } catch (Exception excp) {
        JOptionPane.showMessageDialog(null, "Error on database connection", "Statement error", JOptionPane.ERROR_MESSAGE);
    }//try catch closed

    try {
     String sql = ("SELECT * FROM movements_data ORDER BY No");
     int Numrow=0;

        ResultSet result = stmt.executeQuery(sql);
        while (result.next()) {

            if (run==1){
                 int key =0;
     DefaultTableModel dtm = (DefaultTableModel) tableRecords.getModel();
     key = tableRecords.getRowCount()+1;
     dtm.setRowCount(key);  

            }

            tableRecords.setValueAt(result.getString(1).trim(), Numrow, 0);
            tableRecords.setValueAt(result.getString(2).trim(), Numrow, 1);
            tableRecords.setValueAt(result.getString(3).trim(), Numrow, 2);
            tableRecords.setValueAt(result.getString(4).trim(), Numrow, 3);
            tableRecords.setValueAt(result.getString(5).trim(), Numrow, 4);

   Numrow++;

        }//while closed
       run =0;
    } catch (SQLException sqlex) {
        JOptionPane.showMessageDialog(null, "Error on retrieving values", "Error", JOptionPane.ERROR_MESSAGE);
    }//try catch closed
}//reloaded() closed

I've been asked to apply white box and black box testing techniques on this part of code. Is it possible to do it, without having other classes?