简单工厂模式练习

 输入两个数和运算符，计算出结果。

可以根据工厂模式画出类图，四种（或者更多）运算符，统一运算符接口，并含有run()方法，用于执行运算。

定义一个运算工厂，含有工厂方法，该工厂方法根据用户输入的运算符new出相应的对象。

Main测试

import java.util.Scanner;

public class Main {
    
    public static void main(String args[]){       
        System.out.println("输入两个数和运算符号");         
        Scanner in=new Scanner(System.in); 
        double n1 = in.nextDouble();
        double n2 = in.nextDouble();
         
        String s3 = in.next();
        in.close();
        
      OperatorStore operatorStore = new SimpleOperator(n1,n2,s3);
       operatorStore.runOperator(n1,n2,s3);
       
    }
}

运算接口

public abstract class Operator {
   protected void run (double n1, double n2){
        System.out.println("Operator  run");
    }
}

加减乘除

public  class Plus extends Operator {
    double n1,n2,n3;
    public Plus(double n1 ,double n2){
        this.n1=n1;
        this.n2=n2;
    }
    protected void  run(double n1,double n2){
        n3=n1+n2;
        System.out.println("和为"+n3);
        
    }
}

工厂

public abstract class OperatorStore {
       Operator operator;
       
   public Operator runOperator(double n1 ,double n2,String type){     
       operator = createoperator(type);
       operator.run(n1, n2);
       return operator;
   }
   
   public  abstract Operator createoperator(String type);
}

工厂方法

public class SimpleOperator extends OperatorStore{
        double n1,n2;
          String type;
    
      public SimpleOperator(double n1,double n2,String s3){
        this.n1 = n1;
        this.n2=n2;
        this.type=s3;
    }
    public Operator createoperator(String type) {
        System.out.println(type);
        if(type.equals("+")){
            return new Plus(n1,n2);
        }
        if(type.equals("-")){
            return new subtraction(n1,n2);
        
        }else
             return null;
    }
        
}

执行结果

  

输入两个数和运算符号
3.4 4.5 -
-
差为-1.1