加减乘除

package test;

import java.util.Scanner;

public class Shu {
 public static void main(String[] args) {
  Scanner s=new Scanner(System.in);
  System.out.println("请输入");
  System.out.println("1==加");
  System.out.println("2==减");
  System.out.println("3==乘");
  System.out.println("4==除");
  int shu=s.nextInt();
  switch (shu) {
  case 1:
   Add add=new Add();
   Scanner s1=new Scanner(System.in);
   System.out.println("请输入第一个数");
   double diyi=s1.nextDouble();
   System.out.println("请输入第二个数");
   double dier=s1.nextDouble();
   add.add(diyi,dier);
   break;
  case 2:
   Jian jian=new Jian();
   Scanner s2=new Scanner(System.in);
   System.out.println("请输入第一个数");
   double diyi2=s2.nextDouble();
   System.out.println("请输入第二个数");
   double dier2=s2.nextDouble();
   jian.jian(diyi2,dier2);
   break;
  case 3:
   Cheng cheng=new Cheng();
   Scanner s3=new Scanner(System.in);
   System.out.println("请输入第一个数");
   double diyi3=s3.nextDouble();
   System.out.println("请输入第二个数");
   double dier3=s3.nextDouble();
   cheng.cheng(diyi3,dier3);
   break;
  case 4:
   Chu chu=new Chu();
   Scanner s4=new Scanner(System.in);
   System.out.println("请输入第一个数");
   double diyi4=s4.nextDouble();
   System.out.println("请输入第二个数");
   double dier4=s4.nextDouble();
   chu.chu(diyi4,dier4);
   break;
  default:
   break;
  }
 }

}
class Add{
 public void add(double a,double b){
  double zong=a+b;
  System.out.println("等于"+zong);
 }
}
class Jian{
 public void jian(double a,double b){
  double zong=a-b;
  System.out.println("等于"+zong);
 }
}
class Cheng{
 public void cheng(double a,double b){
  double zong=a*b;
  System.out.println("等于"+zong);
 }
}
class Chu{
 public void chu(double a,double b){
  double zong=a/b;
  System.out.println("等于"+zong);
 }
}