Passing Variable from One class to another, using an ActionListener

I have three classes. The Main class that starts the application, the
ButtonListener class that listens for an events and the Processing
class which does all the data processing.

(Main
Class)----------------------------------------------------------------------------------------------------------------------------------------------------

package Program;

import java.awt.*;
import javax.swing.*;

public class LoginGUI {
     public static void main(String arg[]){

        JFrame login_frame = new JFrame();
        login_frame.setName("");
        login_frame.setSize(1024,576);

        ImagePanel login_panel = new ImagePanel("pictures/
login_bg.gif");
        login_panel.setSize(1024,576);
        login_panel.setVisible(true);
        //login_panel.setLayout(new BoxLayout(login_panel,
BoxLayout.Y_AXIS));

        JLabel lblUsername = new JLabel();
        lblUsername.setText("USERNAME:");
        lblUsername.setOpaque(true);
        lblUsername.setVisible(true);

        JTextField txtbxUsername = new JTextField(10);

        JLabel lblPassword = new JLabel();
        lblPassword.setText("PASSWORD:");
        lblPassword.setOpaque(true);
        lblPassword.setVisible(true);

        JPasswordField txtbxPassword = new JPasswordField(10);

        JButton btnLogin = new JButton();
        btnLogin.setText("LOGIN");
        ButtonListener btnLoginListener = new ButtonListener();
        btnLogin.addActionListener(btnLoginListener);
        btnLogin.setActionCommand("btnLoginClicked");

        login_panel.add(lblUsername);
        login_panel.add(txtbxUsername);
        login_panel.add(lblPassword);
        login_panel.add(txtbxPassword);
        login_panel.add(btnLogin);

        login_frame.add(login_panel);
        login_frame.setVisible(true);
     }

    }

(ButtonListener
Class)---------------------------------------------------------------------------------------------------------------------------------------------------------------

package Program;

import java.awt.event.*;

public class ButtonListener implements ActionListener{
    public void actionPerformed(ActionEvent evt){
        String Username = "";
        String Password = "";

        String action = evt.getActionCommand();
        if (action.equals("btnLoginClicked")){
            Processing LoginProcessing = new Processing();
            LoginProcessing.Login(Username,Password);
        }
     }
}

(Processing
Class)-------------------------------------------------------------------------------------------------------------------------------------------------------------------

package Program;

import javax.swing.*;

public class Processing {
    public void Login(String username, String password){
        JFrame fLogin = new JFrame();
        fLogin.setSize(1024,576);

        JPanel pLogin = new JPanel();
        pLogin.setSize(1024,576);

        fLogin.add(pLogin);
        fLogin.pack();
        fLogin.setVisible(true);
    }
}

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Everything so far, works just fine. When I click on the Login Button
in the Main Class, the event is picked up by the ButtonListener Class
and the Processing Class creates a new frame. What I need to happen,
is for the text of the Username and Password textboxes in the Main
Class to be sent through the Event Listener and on to the Processing
class. Or whatever other method there is to get the username and
password over to the Processing Class, so I can then check it against
the database.

I have spent three days reading books and online information to see if
I can find a solution. All I can find is how to send variables from
one class to another, but that information doesn't seem to work with
an action listener.