抽象类－编程实现运算类（java）

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抽象类－编程实现运算类

题目描述

编程实现运算类(1)定义抽象类Operation，有double型数据成员numberA、numberB，有抽象方法getResult()(2)定义Operation的4个子类，分别实现加、减、乘、除四则运算(3)定义类OperationFactory：有静态方法Operation createOperate(String operate); 根据形参operate的值创建相应加、减、乘、除类的对象，赋给抽象类引用后返回(4)定义测试类及主方法：用户从键盘输入运算数及运算符，根据运算符调用OperationFactory类的静态方法，创建相应实例，设置运算数，输出运行结果

 

输入描述

样例输入(每次运行输入一个式子：数据与运算符之间一个空格间隔)

 

输出描述

一行输出结果：冒号、感叹号均为中文标点

 

输入样例

56 + 1234 / 1745 / 0

 

输出样例

结果是：68.0结果是：2.0

除数不能为0！

import java.util.Scanner;
abstract class Operation
{
     double numberA,numberB;
     abstract double getResult() throws Exception;
}
class AddOperation extends Operation
{
     double getResult() throws Exception
     {
          return numberA+numberB;
    }
}
class subOperation extends Operation
{
     double getResult() throws Exception
     {
          return numberA-numberB;
    }
}
class chengOperation extends Operation
{
     double getResult() throws Exception
     {
          return numberA*numberB;
    }
}
class DivideOperation extends Operation{
       double getResult() throws Exception
       {
           if(numberB==0)
                throw new Exception("除数不能为0!");
           return numberA/numberB;
       }
}
class OperationFactory{
       public static Operation createOperate(String operate)
       {
            if(operate.equals("+"))
                return new  AddOperation();
            if(operate.equals("-"))
                return new  subOperation();
            if(operate.equals("*"))
                return new  chengOperation();
            else //if(operate.equals("/"))
                 return new DivideOperation();
        }
}
public class Main{
     public static void main(String[] args)
     {
          double x,y,z;
          String op;
          Scanner in=new Scanner(System.in);
          while(in.hasNext())
           {
                 x=in.nextDouble();
                 op=in.next();
                y=in.nextDouble();
                Operation oper=OperationFactory.createOperate(op);
                oper.numberA=x;
               oper.numberB=y;
              try{
                     z=oper.getResult();
                     System.out.print("结果是:"+z);
              }
              catch(Exception e){
                   System.out.println(e.getMessage());
              }
          }
     }
}