题解 | #简单计算器#

import java.util.Scanner;
import java.lang.String;
public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String str=sc.nextLine();
        String[] strs=str.split("[+\\-*/]");
        if(strs.length<2)//先判断再分
        {
            System.out.println("Invalid operation!");
        }else{
            double a=Double.parseDouble(strs[0]);
            String F=str.substring(strs[0].length(),strs[0].length() + 1);
            double b=Double.parseDouble(strs[1]);
            switch(F)
            {
                case "+":System.out.printf("%.4f+%.4f=%.4f",a,b,(a+b));break;
                case "-":System.out.printf("%.4f-%.4f=%.4f",a,b,(a-b));break;
                case "*":System.out.printf("%.4f*%.4f=%.4f",a,b,(a*b));break;
                case "/":
                    if(b==0)
                    {
                        System.out.println("Wrong!Division by zero!");break;
                    }else{
                        System.out.printf("%.4f/%.4f=%.4f",a,b,(a/b));break;
                     }
            }
        }
    }
}