我的第四個程序 java實現加減乘除

import java.util.Scanner;

public class Test {


    public static void main(String [] args) { 


         Scanner sc = new Scanner(System.in); 

System.out.println("請輸入算法："); 
         String go = sc.next();

         
System.out.println("請輸入第一個數："); 
         Double a = sc.nextDouble(); 
         
System.out.println("請輸入第二個數："); 
         Double b =  sc.nextDouble();


if(go.equals("+")){
    Double sum = a+b;
    System.out.println("他們的和為"+sum);
}

if(go.equals("-")){
     Double sum = a-b;
    System.out.println("他們的差為"+sum);
}

if(go.equals("*")){
     Double sum = a*b;
    System.out.println("他們的積為"+sum);
}

if(go.equals("/")){
    Double sum = a/b;
    System.out.println("他們的商為"+sum);
}

         

     
        
}
}