臭臭/文

import java.util.Scanner;

public class Calculator {

 double sum(double x, double y) {// 形参
  return x + y;
 }

 double minus(double x, double y) {
  return x - y;
 }

 double power(double x, double y) {
  return x * y;
 }

 double divide(double x, double y) {
  return x / y;
 }
 void printWelcome(){
  System.out.println("1-加法");
  System.out.println("2-减法");
  System.out.println("3-乘法");
  System.out.println("4-除法");
  System.out.println("5-退出");
  System.out.println("请输入你的选择");
 }
}

public class UseCal {

 
 public static void main(String[] args) {
  Scanner scan=new Scanner(System.in);
  double x,y;
  Calculator cal=new Calculator();
  while(true){
  cal.printWelcome();
        int c=scan.nextInt();
        switch(c){
        case 1:
         System.out.println(" 2 num");
         x=scan.nextDouble();
         y=scan.nextDouble();
         System.out.println("和是："+cal.sum(x, y));
         break;
        case 2:
         System.out.println(" 2 num");
         x=scan.nextDouble();
         y=scan.nextDouble();
         System.out.println("差是："+cal.minus(x, y));
         break;
        case 3:
         System.out.println(" 2 num");
         x=scan.nextDouble();
         y=scan.nextDouble();
         System.out.println("积是："+cal.power(x, y));
         break;
        case 4:
         while(true){
         System.out.println(" 2 num");
         x=scan.nextDouble();
         y=scan.nextDouble();
         if(y==0){
          System.out.println("除数不能为零,请重新输入");
         }else{
           System.out.println("商是："+cal.divide(x, y));}
              break;
         }
           
         break;
        case 5:
            return;
         //System.exit(0);
        default :
         System.out.println("bad choice");
       
        }
  }

   }
}