Java写一个计算机，要求实现加减乘除功能，并且能够循环接收新的数据，通过用户交互来实现

     import java.util.Scanner;
     
     //写一个计算机，要求实现加减乘除功能，并且能够循环接收新的数据，通过用户交互来实现
     public class Demo08 {
         public static void main(String[] args) {
             int a=0;
             int b=0;
             char s='\u0000';
             Demo08 demo08 = new Demo08();
             Scanner scanner1 = new Scanner(System.in);
             System.out.println("请输入第一个操作数：");
             if(scanner1.hasNextInt()){
                 a = scanner1.nextInt();
             }
             Scanner scanner2 = new Scanner(System.in);
             System.out.println("请输入第二个操作数：");
             if(scanner2.hasNextInt()){
                 b = scanner2.nextInt();
             }
             Scanner scanner3 = new Scanner(System.in);
             System.out.println("请输入操作符：");
             if(scanner3.hasNextLine()){
                 s = scanner3.next().charAt(0);
                 demo08.cal(a,b,s);
             }
             scanner1.close();
             scanner2.close();
             scanner3.close();
         }
         int a;
         int b;
         //计算
         public void cal(int a,int b,char s){
             switch(s){
                 case '+':
                     System.out.println(plus(a,b));
                     break;
                 case '-':
                     System.out.println(sub(a,b));
                     break;
                 case '*':
                     System.out.println(mul(a,b));
                     break;
                 case '/':
                     System.out.println(exc(a,b));
                     break;
             }
         }
         //加
         public int plus(int a,int b){
             return a+b;
         }
         //减
         public int sub(int a, int b){
             if(a>=b){
                 return a-b;
             }else{
                 return b-a;
             }
         }
         //乘
         public int mul(int a,int b){
             return a*b;
         }
         //除
         public int exc(int a,int b){
             if(b==0){
                 System.out.println("除数不能为0");
                 return -1;
             }else{
                 return a/b;
             }
         }
     }
     ```