(Beginner) Simple Application & Graphics Help

Hi all, I have a few questions regarding a program meant to output some simple information. I created an application with a frame, panel, JButtons, and JLabels that all involve displaying an integer that increments or decrements by 1 when pressed by either button, respectively. My problem is that everything is displayed correctly, but the JLabel displaying the integer doesn't update when either button is pressed. Here's my code:

Code java:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
public class AddSubtractGUI
{
    private int WIDTH = 300; 
    private int HEIGHT = 75;
    private int pushTotal = 50; //integer that is incremented/decremented
 
    private JFrame frame;
    private JPanel panel;
    private JLabel totalDisplay, pushTotalDisplay; //displays the push total
    private JButton addPush, subPush; //addition and subtraction buttons
 
    public AddSubtractGUI()
    {
        frame = new JFrame ("Add/Subtract"); //title of application
        frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE); //closes application
 
        totalDisplay = new JLabel ("Total : ");
        pushTotalDisplay = new JLabel ("50");
 
        addPush = new JButton ("Add!");
        subPush = new JButton ("Subtract!");
 
        panel = new JPanel();
        panel.setPreferredSize (new Dimension(WIDTH, HEIGHT));
        panel.setBackground (Color.cyan);
        panel.add (totalDisplay);
        panel.add (pushTotalDisplay);
        panel.add (addPush);
        panel.add (subPush);
 
        frame.getContentPane().add (panel); //package to display all components of app
 
    }
 
    public void display() //enables frame
        {
            frame.pack();
            frame.setVisible(true);
        }
 
    private class AddListener implements ActionListener //addition button upon press
        {
            public void actionPerformed (ActionEvent event)
            {
                pushTotal++;
                pushTotalDisplay.setText(Integer.toString (pushTotal) );
            }
        }
 
        private class SubListener implements ActionListener //subtraction button upon press
        {
            public void actionPerformed (ActionEvent event)
            {
                pushTotal--;
                pushTotalDisplay.setText(Integer.toString (pushTotal) );
            }
        }
    }
 
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public class AddSubtractDriver //driver program
{
    public static void main (String[] args)
    {
        AddSubtractGUI converter = new AddSubtractGUI();
        converter.display();
    }
}

I'm trying to get my JButtons to update properly so that the push total updates when they are pressed, and corresponds with the operation that they are labeled as.

I run my code through my driver as an application, rather than as an applet. I apologize for any ambiguity, this is my first post. Thanks!