Java怎么实现返回上级菜单请用Java写一串简单的代码

以下是一个简单的Java代码示例，演示如何通过递归函数实现返回上级菜单：

import java.util.Scanner;

public class Menu {
    public static void main(String[] args) {
        showMainMenu();
    }

    public static void showMainMenu() {
        System.out.println("1. 子菜单1");
        System.out.println("2. 子菜单2");
        System.out.println("3. 返回上级菜单");
        Scanner scanner = new Scanner(System.in);
        int choice = scanner.nextInt();
        switch (choice) {
            case 1:
                showSubMenu1();
                break;
            case 2:
                showSubMenu2();
                break;
            case 3:
                System.out.println("返回上级菜单");
                showMainMenu();
                break;
            default:
                System.out.println("无效的选择");
                showMainMenu();
                break;
        }
    }

    public static void showSubMenu1() {
        System.out.println("1. 子菜单1-1");
        System.out.println("2. 子菜单1-2");
        System.out.println("3. 返回上级菜单");
        Scanner scanner = new Scanner(System.in);
        int choice = scanner.nextInt();
        switch (choice) {
            case 1:
                System.out.println("执行子菜单1-1");
                break;
            case 2:
                System.out.println("执行子菜单1-2");
                break;
            case 3:
                System.out.println("返回上级菜单");
                showMainMenu();
                break;
            default:
                System.out.println("无效的选择");
                showSubMenu1();
                break;
        }
    }

    public static void showSubMenu2() {
        System.out.println("1. 子菜单2-1");
        System.out.println("2. 子菜单2-2");
        System.out.println("3. 返回上级菜单");
        Scanner scanner = new Scanner(System.in);
        int choice = scanner.nextInt();
        switch (choice) {
            case 1:
                System.out.println("执行子菜单2-1");
                break;
            case 2:
                System.out.println("执行子菜单2-2");
                break;
            case 3:
                System.out.println("返回上级菜单");
                showMainMenu();
                break;
            default:
                System.out.println("无效的选择");
                showSubMenu2();
                break;
        }
    }
}

在该示例中，`showMainMenu()`函数显示主菜单，并根据用户输入调用不同的子菜单函数。当用户选择“返回上级菜单”时，调用`showMainMenu()`函数以返回上一级菜单。子菜单函数的实现类似，只是菜单内容不同。