how to have an else block execute only once in a for loop

I have a for loop which is used to compare user login details to launch the next screen of an application.

If the user-entered fields are successfully matched to data in an ArrayList returned from a database the program launches next screen -- if they are not matched an error message is outputted to the user using JOptionPane.

My problem is the error message is outputted for every iteration of the for loop but I want the message to only be displayed once.

  //if name or password are NOT left blank proceed with the check otherwise output error message in the text area
    if (!name.equals("") && !password.equals("")) {
        for (int i = 0; i < passwords.size(); i++) {
            if (name.equals(userNames.get(i)) && (password.equals(passwords.get(i)))) {
                myHomeGUI.setVisible(true);
                break;
            } else {
                JOptionPane.showMessageDialog(null,"Sorry, no user recognized with those credentials\nPlease try again");
            }
        }//end for loop 
    } else {
        JOptionPane.showMessageDialog(null,"Sorry, no fields can be left blank");
    }//end