String username=null, password=null;
    MainMenu men =new MainMenu().getMainMenu();
    String query="SELECT employeeID, password FROM employee WHERE employeeID = ? AND password = ?";

    try{
        PreparedStatement pstmt = con.prepareStatement(query);
        pstmt.setString(1, UNField.getText());
        pstmt.setString(2, new String(PWField.getPassword()));

        ResultSet rs = pstmt.executeQuery();
        while(rs.next()){
            username=rs.getString(1);
            password=rs.getString(2);
        }
    } catch (SQLException e) {
        msgDlg.setMessage("Error in statment! "+e.getMessage());
        msgDlg.setVisible(true);
    }

    if(UNField.getText().isEmpty() || new String(PWField.getPassword()).isEmpty()){
        msgDlg.setMessage("Enter login Details");
        msgDlg.setVisible(true);
    }else if(username==null || password==null){
        msgDlg.setMessage("That User doesn't exist");
        msgDlg.setVisible(true);
    }else if(username.equals(UNField.getText()) && password.equals( new String(PWField.getPassword()))){
       men.setVisible(true);
       this.setVisible(false);
       this.dispose();
    }else{
       msgDlg.setMessage("Login is failed");
       msgDlg.setVisible(true);
    }