JList空白，不显示任何内容。尝试了其他网站建议的一切

Question

下面：

private static DefaultListModel qpape;
//@SuppressWarnings("null")
public void disp() throws SQLException
{
  qpape=new DefaultListModel();
  jList2=new JList(qpape);
  String sql1="SELECT URL from RECORD";
  PreparedStatement st = db.conn.prepareStatement(sql1, 
      Statement.RETURN_GENERATED_KEYS);
  ResultSet rs1=st.executeQuery(sql1);

  while(rs1.next())
  { 
    String lnk=rs1.getString("URL");
    System.out.println(lnk);
    //qpape.addElement(lnk);
    ((DefaultListModel)jList2.getModel()).addElement(lnk);
  }

  rs1.close();
}

public static void main(String args[]) throws SQLException, IOException {
  fetch();
  Qpapers obj=new Qpapers();
  if(obj!=null) { 
    obj.disp();
    jList2.setModel(qpape);
  }

  /* Set the Nimbus look and feel */
  //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
  /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
   * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
   */
  try {
    for (javax.swing.UIManager.LookAndFeelInfo info : 
         javax.swing.UIManager.getInstalledLookAndFeels()) {
      if ("Nimbus".equals(info.getName())) {
        javax.swing.UIManager.setLookAndFeel(info.getClassName());
        break;
      }
    }
   } catch (ClassNotFoundException ex) {
     java.util.logging.Logger.getLogger(Qpapers.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
   } catch (InstantiationException ex) {
     java.util.logging.Logger.getLogger(Qpapers.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
   } catch (IllegalAccessException ex) {
     java.util.logging.Logger.getLogger(Qpapers.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
   } catch (javax.swing.UnsupportedLookAndFeelException ex) {
     java.util.logging.Logger.getLogger(Qpapers.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
   }
   //</editor-fold>

   /* Create and display the form */
   java.awt.EventQueue.invokeLater(new Runnable() {
     @Override
     public void run() {
       new Qpapers().setVisible(true);
     }
   });
 }

 // Variables declaration - do not modify                     
 private static javax.swing.JList jList2;
 private javax.swing.JScrollPane jScrollPane2;
 // End of variables declaration                   
}