Manipulating a combo box

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Java

Would someone please give me an example of a program that increments and decrements values with just the use of combo box and buttons, no other stuffs like a JDialog or even JTable. I'm having a hard time trying to understand complicated programs after all I'm just a newbie in java, so I need a very simple one that is easy to understand.

the code is this:

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.Scanner;

    public class EditStack {
    private JComboBox comboBox = new JComboBox();
    private JButton button = new JButton("Add Order");
    private JButton button_1 = new JButton("Decrease Order");
    JComboBox combo;
    private static String z  = "";
    private static String w  = "";
    private static String x  = "";
    private static String a  = "";
    private int numClick = 0;
    
public EditStack() {

    String mgaPagkainTo[] = {"PM1 (Paa/ Spicy Paa with Thigh part)","PM2 (Pecho)","PM3 (Pork Barbeque 4 pcs.)","PM4 (Bangus Sisig)","PM5 (Pork Sisig)","PM6 (Bangus Inihaw)","SM1 (Paa)","SM2 (Pork Barbeque 2 pcs.)","Pancit Bihon","Dinuguan at Puto","Puto","Ensaladang Talong","Softdrinks","Iced Tea","Halo-Halo","Leche Flan","Turon Split"};
    JFrame frame = new JFrame("Mang Inasal Ordering System");
    JPanel panel = new JPanel();
    combo = new JComboBox(mgaPagkainTo);
    combo.setBackground(Color.gray);
    combo.setForeground(Color.red);
    panel.add(combo);
    panel.add(button);
    panel.add(button_1);
    frame.add(panel);

    combo.addActionListener(new ActionListener(){
    public void actionPerformed(ActionEvent e){
        String str = (String)combo.getSelectedItem();
        a = str;
        EditLang messageOrder1 = new EditLang();
        messageOrder1.ShowOrderPo();
       }
    });

    button.addActionListener(new ActionListener() { //this is the part I'm stuck with
        public void actionPerformed(ActionEvent e) {
            String selectedItem = (String) comboBox.getSelectedItem(); // I want here to display the selected item in the combo box
            numClick++ // and then increment it whenever I clicked on the add button
        }
    }
    );
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(300,250);
    frame.setVisible(true);
  }

  public static void main(String[] args) {
  Scanner inp = new Scanner(System.in);
  boolean ulitinMoPows = true;
  boolean tryAgain = true;

    System.out.print("\nInput Customer Name: ");
    String customerName = inp.nextLine();
    w = customerName;
    System.out.print("\nInput Cashier Name: ");
    String user = inp.nextLine();
    z = user;
   do{
    System.out.print("\nInput either Dine In or Take Out: ");
    String dInDOut = inp.nextLine();
    x = dInDOut;
        if (x.equals("Dine In") || x.equals("Take Out")){
         System.out.print("");
         ulitinMoPows = false;
         }
        else{
         JOptionPane.showMessageDialog(null, "Try again! Please input Dine In or Take Out only!","Error", JOptionPane.ERROR_MESSAGE);
             ulitinMoPows = true;
             System.out.print ("\f");
            }
     }while(ulitinMoPows);
     do{
    System.out.print("\nInput password: ");
    String pass = inp.nextLine();
    if(pass.equals("admin")){
        EditLang messageShowMenu = new EditLang();
        messageShowMenu.ShowMo();
        tryAgain = false;
    }
    if(!pass.equals("admin")){
        JOptionPane.showMessageDialog(null, "Try again! Invalid password!","Error Logging-In", JOptionPane.ERROR_MESSAGE);
    tryAgain = true;
     System.out.print ("\f");
    }
}while(tryAgain);

EditStack j = new EditStack();
    }
  public static String kuhaOrder()
  {
  return a;
  }

  public static String kuhaUserName()
  {
  return z;
  }

  public static String kuhaCustomerName()
  {
  return w;
  }

  public static String kuhaSanKainPagkain()
  {
  return x;
  }  
}
//Class of EditLang:

public class EditLang {

public void ShowMo(){
    String user = EditStack.kuhaUserName();
    System.out.print("\n\n\t\tCashier: " +user);
    String dInDOut = EditStack.kuhaSanKainPagkain();
    System.out.print("                          "+dInDOut);
    String customerName = EditStack.kuhaCustomerName();
    System.out.print("\n\t\tCustomer Name: " +customerName);
}

public void ShowOrderPo() {
    String order = EditStack.kuhaOrder();
    System.out.print("\t\t\t\t\n " +order);

}
}
//I want to do something like that. Any help will be appreciated thanks!