Generar un menú que tenga la opción: 1. Sumar

import javax.swing.JOptionPane;
public class Menu {
    public static void main(String[] args) {
        int opcion = 0;
        do {
            try {
                opcion = Integer.parseInt(JOptionPane.showInputDialog(null, "1. Sumar\n2. Restar\n3. Multiplicar\n4. Dividir\n0. Salir", "  MENU DE OPCIONES  ", JOptionPane.QUESTION_MESSAGE));
                switch (opcion){
                    case 0:
                        break;
                    case 1:
                        JOptionPane.showMessageDialog(null,"La suma es: " + sumar());
                        break;
                    case 2:
                        JOptionPane.showMessageDialog(null,"La resta es: " + restar());
                        break;
                    case 3:
                        JOptionPane.showMessageDialog(null,"La multiplicacion es: " + multiplicar());
                        break;
                    case 4:
                        JOption