疑惑：1.我不知道如何创建showMenu max accumulative 这三个方法并调用这些方法2.不知道如何使用户输入整数并完成对应的方法或选择0就可以退出（如下图是所要呈现的效果）

疑惑：1.我不知道如何创建showMenu max accumulative 这三个方法并调用这些方法2.不知道如何使用户输入整数并完成对应的方法或选择0就可以退出
（如下图是所要呈现的效果）

package com.yelang.case3;

import java.util.Scanner;

public class Case3Main {
    
    public void showMenu() {
        System.out.println("Please choose the method");
        System.out.println("1- Method max");
        System.out.println("2 - Method accumulative-total");
        System.out.println("3 - Quit");
    }
    
    public int max(int num1,int num2) {
        return num1 - num2 > 0 ? num1 : num2;
    }
    
    public int accumulative(int num1,int num2) {
        int result = 0;
        for(int i = num1;i<=num2;i++) {
            result += i;
        }
        return result;
    }

    public static void main(String[] args) {
        Case3Main c3 = new Case3Main();
        Scanner input = new Scanner(System.in);
        int target = 0;
        do {
            c3.showMenu();
            target = input.nextInt();
            if(target == 1) {
                System.out.println("the 1st number is:");
                int num1 = input.nextInt();
                System.out.println("the 2nd number is:");
                int num2 = input.nextInt();
                System.out.println("The max is:"+c3.max(num1, num2));
            }else if(target == 2) {
                System.out.println("the start number is:");
                int num1 = input.nextInt();
                System.out.println("the end number is:");
                int num2 = input.nextInt();
                System.out.println("the total is :" + c3.accumulative(num1, num2));
            }else if(target == 3) {
                System.out.println("Mission accomplished!");
            }else if(target == 0){
                System.out.println("Invalid selection, please try again");
            }
            System.out.println("=========================================");
        } while (target != 3 );
        
        input.close();
    }
}