铁铁们，这个这个呀，蒙了蒙了

emmm用个switch不就行了

public class aa {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("输入第一个数");
        int A = sc.nextInt();
        System.out.println("输出第二个数");
        int B = sc.nextInt();
        System.out.println("输入运算方式");
        String symbol = sc.next();

        switch (symbol) {
        case "+":
            System.out.println(A + B);
            break;
        case "-":
            System.out.println(A - B);
            break;
        case "*":
            System.out.println(A * B);
            break;
        case "/":
            System.out.println(A / B);
            break;
        }
    }
}

可以用Switch：
代码：

#include <stdio.h>

int main()
{
    char ch;
    int a, b;
    scanf("%d%d %c", &a, &b, &ch);
    switch(ch)
    {
        case '+':
            printf("%d\n", a+b);
            break;
        case '-':
            printf("%d\n", a-b);
            break;
        case '*':
            printf("%d\n", a*b);
            break;
        case '/':
            {
                if(b == 0)
                {
                    printf("Divided by zero!\n");
                    break;
                }
                printf("%d\n", a/b);
                break;
            }
        default:
            printf("Invalid operator!\n");

    }

    return 0;
}