Learn How to Create a TextEditor with Java - Creating classes

[retrogamingbros]

I know these are a bit old, but my back button doesn't work! What's wrong with my code:
Register:
package dev.equite.main;
//Awt Imports
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import

//Swing Imports
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;

public class Register extends JPanel implements ActionListener{
JLabel userL = new JLabel("New Username: ");
JTextField userTF = new JTextField();
JLabel passL = new JLabel("New Password: ");
JPasswordField passTF = new JPasswordField();
JLabel passLC = new JLabel("Password Again: ");
JPasswordField passC = new JPasswordField();
JButton register = new JButton("Register");
JButton back = new JButton("Back");

public Register() {
JPanel loginP = new JPanel();
loginP.setLayout(new GridLayout(4, 2));
loginP.add(userL);
loginP.add(userTF);
loginP.add(passL);
loginP.add(passTF);
loginP.add(passLC);
loginP.add(passC);
loginP.add(register);
loginP.add(back);

back.addActionListener(this);
add(loginP);
}

@Override
public void actionPerformed(ActionEvent e) {
if(e.getSource() == back) {
Login login = (Login) getParent();
login.cl.show(login, "login");
}
}
}
Login:
package dev.equite.main;
//Awt imports
import java.awt.CardLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import
//Swing imports
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;

public class Login extends JPanel implements ActionListener{
JLabel userL = new JLabel("Username: ");
JTextField userTF = new JTextField();
JLabel passL = new JLabel("Password: ");
JPasswordField passTF = new JPasswordField();
JPanel loginP = new JPanel(new GridLayout(3, 2));
JPanel panel = new JPanel();
JButton login = new JButton("Login");
JButton register = new JButton("Register");
CardLayout cl;
Login(){
setLayout(new CardLayout());
loginP.add(userL);
loginP.add(userTF);
loginP.add(passL);
loginP.add(passTF);


loginP.add(login);
loginP.add(register);
panel.add(loginP);
add(panel, "l");
cl = (CardLayout) getLayout();
}

@Override
public void actionPerformed(ActionEvent e) {
add(new Register(), "register");
cl.show(this, "register");
}

public static void main(String[] args) {
JFrame window = new JFrame();
window.setTitle("Equiteer");

window.setSize(650, 650);
Login login = new Login();
window.add(login);
window.setVisible(true);
}
}