用JAVA编写一个计算器

package Function;

import java.util.Scanner;

public class Calc {
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        System.out.println("请输入第一个数字:");
        int c=scanner.nextInt();
        System.out.println("请输入第二个数字:");
        int d=scanner.nextInt();
        System.out.println("请输入运算符(+、-、*、/):");
        String operator= scanner.next();
        switch (operator){
            case "+":
                System.out.println("运算结果为:"+add(c,d));
                break;
            case "-":
                System.out.println("运算结果为:"+sub(c,d));
                break;
            case "*":
                System.out.println("运算结果为:"+mult(c,d));
                break;
            case "/":
                if (d==0){
                    System.out.println("第二个数字不能为0,否则除法运算无意义！");
                }else {
                    System.out.println("运算结果为:" + div(c, d));
                }
                break;
            default:
                System.out.println("运算符输入错误!");
        }
        scanner.close();
     }
    public static int add(int a,int b){return a+b;}
    public static int sub(int a,int b){return a-b;}
    public static int mult(int a,int b){return a*b;}
    public static int div(int a,int b){return a/b;}
}