java实验接口实现计算器功能（很水）

自己闲着就写了一下，纪念纪念

我写的类比较多，

import java.util.Scanner;

public class Jisuanqi {
    public static void main(String[] args) {
        double a,b;
        char x;
        System.out.println("切记输入的数字与符号要留出空格要不然会报错的");
        while(true) {
            Scanner cin = new Scanner(System.in);
            a = cin.nextDouble();
            x = cin.next().charAt(0);
            b = cin.nextDouble();
            Usefuhao u = new Usefuhao();
            u.start(x, a, b);
        }
    }
}

public class Usefuhao {
    public void start(char x,double a,double b){
        switch (x){
            case '+':
                jia j = new jia();
                System.out.println("a + b = "+j.yunxin(a,b));
                break;
            case '-':
                jian jan = new jian();
                jan.yunxin(a,b);
                System.out.println("a - b = "+jan.yunxin(a,b));
                break;
            case '*':
                chen c = new chen();
                System.out.println("a * b = "+c.yunxin(a,b));
                break;
            case '/':
                chu cu = new chu();
                System.out.println("a / b = "+cu.yunxin(a,b));
                break;
                default:
                    System.out.println("您输入的符号不在我的计算范围之内");
                    break;
        }
    }
}


public abstract interface fuhao {
    public abstract double yunxin(double n,double b);
}

public class jia implements fuhao {
    public double yunxin(double a,double b) {
        return a+b;
    }
}
public class jian implements fuhao{
    public double yunxin(double a,double b){
        return  a-b;
    }
}
public class chen implements fuhao{
    public double yunxin(double a,double b){
        return a*b;
    }
}
public class chu implements fuhao{
    public double yunxin(double a,double b){
        return a/b;
    }
}