JAVA每日一题05

题目：定义接口OneToN,在接口中定义方法jisuan(int n);定义两个类来实现接口,分别从1~n的阶乘和累加和.(要求:在主方法中利用接口的多态实现计算.)

package com.test; 

/** 
* 计算接口 
* @author 
* 
*/ 
public interface OneToN { 
public int jisuan(int n); 
} 

package com.test; 

/** 
* 1-N累加实现类 
* @author duyiwuer 
* 
*/ 
public class Add implements OneToN { 

public int jisuan(int n) { 
int sum = 0; 
for (int i = 1; i <= n; i++) { 
sum += i; 
} 
return sum; 
} 

} 

package com.test; 

/** 
* 1-N阶乘实现类 
* @author 
* 
*/ 
public class Mul implements OneToN { 

public int jisuan(int n) { 
int sum = 0; 
for (int i = 1; i <= n; i++) { 
sum *= i; 
} 
return sum; 
} 

/** 
* 测试方法 
* @param args 
*/ 
public static void main(String[] args) { 
OneToN ot1= new Add(); 
OneToN ot2 = new Mul(); 
ot1.jisuan(3); 
ot1.jisuan(5); 
} 
}