Java简单计算器的实现

import java.util.Scanner;

//简易计算器 实现加减乘除
public class Demo11 {
     public static void main(String[] args) {
       Scanner scanner = new Scanner(System.in);
       System.out.println("请输入要计算的第一个数字：");
       int num1 = 0;
       int num2 = 0;
       int d = 0;
         num1 = scanner.nextInt();
       System.out.println("请输入运算符：");
         String c = scanner.next();
       System.out.println("请输入要计算的第二个数字：");
         num2 = scanner.nextInt();
//       Demo11 de = new Demo11();
//       int c = add(1,2);
//       if(c == "+")
//       {
//         add(1,2);
//       }
         switch(c){
           case "+": d = add(num1,num2);
           break;
           case "-": d = reduce(num1,num2);
           break;
           case "*": d = multi(num1,num2);
           break;
           case "/": d = division(num1,num2);
           break;
         }

       System.out.println("运算结果为："+d);
       scanner.close();
     }
     public static int add(int a,int b){
       return a+b;
     }
     public static int reduce(int a,int b){
       return a-b;
     }
     public static int multi(int a,int b){
       return a*b;
     }
     public static int division(int a,int b){
       return a/b;
     }

}