为什么在jButton1MouseClicked上获取java.lang.NullPointerException并访问$ 300？

Question

我正在尝试通过使用xampp for ATM应用程序从数据库中获取卡号和PIN来进行登录，方法是提供输入卡号和PIN，然后显示错误为：

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at Atmcardno.jButton1MouseClicked(Atmcardno.java:228)
at Atmcardno.access$300(Atmcardno.java:15)
at Atmcardno$4.mouseClicked(Atmcardno.java:128)

我的jButton1代码用于登录并获取卡号和密码如下所示。我一直在用Java swing编程，需要帮助。

    System.out.println("Starting...");

          if(((cardno.getText()).equals("")) && (pwd.getPassword().equals("")))
          {
           JOptionPane.showMessageDialog(this,"Please enter ATM Card No and PIN No.","Warning!!!",JOptionPane.WARNING_MESSAGE);
       }
          try{
              System.out.print("Starting1...");
                int foundrec=0;
                Class.forName("com.mysql.jdbc.Driver");
                Connection con= DriverManager.getConnection("jdbc:mysql://localhost:3306/atmdb","root","");
                System.out.println("Connected to database.");
      PreparedStatement ps= con.prepareStatement("select* from accountdetail where atmno='"+cardno.getText()+"' and pinno='"+pwd.getPassword()+"'");
                ResultSet rs= ps.executeQuery();
                while(rs.next())
                {
                    atno=rs.getInt(1);
                    System.out.println(atno);
                    acno=rs.getInt(2);
                    System.out.println(acno);
                    pno= rs.getInt(3);
                    System.out.println(pno);
                    String cardname= rs.getString(5);
                    System.out.println(cardname);
                    String expdate= rs.getString(7);

                    try
                    {
                        SimpleDateFormat sdf= new SimpleDateFormat("yyyy-mm-dd");
                        Date d1= sdf.parse(curdate);
                        Date d2= sdf.parse(expdate);

                        System.out.println("Expiry date of ATM card is "+sdf.format(d2));
                        System.out.println("Today's date is "+sdf.format(d1));

                        if(d1.compareTo(d2)>=0)
                        {
                            JOptionPane.showMessageDialog(null, "Hello "+cardname);
                      //      new AccountType().setVisible(true);
                        }
                        else if(d1.compareTo(d2)<0)
                        {
                            JOptionPane.showMessageDialog(this, "Your ATM card is out of expiry date, please visit nearest branch for more information.","Warning",JOptionPane.WARNING_MESSAGE);
                            new Welcome().setVisible(true);
                          this.setVisible(false);  
                        }
                     }
                    catch(ParseException pe)
                         {
                              System.out.println("Exception in date format. "+pe);
                              pe.printStackTrace();
                         }
                    foundrec=1;
                }

                if(foundrec==0)
                {
                    JOptionPane.showMessageDialog(null, "Invalid ATM card no. or PIN no. ","Warning",JOptionPane.WARNING_MESSAGE);

                }

            }
            catch(Exception e) {
                e.printStackTrace();
            }