用Java基础语句实现计算器的基本功能（利用switch进行用户交互）

import java.util.Scanner;

public class App{
    public static void main(String[] args){
        double result=0;

System.out.println("请输入需要进行运算的第一个数:");
Scanner scanner=new Scanner(System.in);
int a=scanner.nextInt();

System.out.println("请输入需要进行什么运算(+,-,*,/):");
Scanner scanner2=new Scanner(System.in);
String mark=scanner2.nextLine();

System.out.println("请输入需要进行运算的第二个数:");
Scanner scanner3=new Scanner(System.in);
int b=scanner3.nextInt();


    switch(mark){
        case "+":result=add(a,b);
        break;
        case "-":result=substract(a,b);
        break;
        case "*":result=multiply(a, b);
        break;
        case "/":result=divide(a, b);
        break;
    

}
System.out.print(a+mark+b+"="+result);
scanner.close();
scanner2.close();
scanner3.close();
    }
    public static int add(int a,int b){
        return a+b;
    }
    public static int substract(int a,int b){
        return a-b;
    }
    public static int multiply(int a,int b){
        return a*b;
    }
    public static double divide(int a,int b){
        return (double)(a/b);
    }
}