按要求编写Java程序： 编写一个接口：InterfaceA，只含有一个方法int method(int n)； 编写一个类：ClassA来实现接口InterfaceA，实现int met

Posted 2020-08-09

package com.homework2;

public class ClassA implements InterfaceA {

    @Override
    public int method(int n) {
        int sum = 0;
        for(int i = 0; i<=n;i++)
        {
            sum+=i;
        }
        return sum;
    }

}

package com.homework2;

public class ClassB implements InterfaceA {

    @Override
    public int method(int n) {
        int sum = 1;
        for(int i = 1; i<=n;i++)
        {
            sum*=i;
        }
        return sum;
        
    }

}

package com.homework2;

public interface InterfaceA {

    
    //定义抽象方法
    int method(int n);
}

package com.homework2;

public class E {

    public static void main(String[] args) {
        
        ClassA a= new ClassA();
        InterfaceA ia= a;
        System.out.println(a.method(10));

        
        ClassB b= new ClassB();
        InterfaceA ib= b;
        System.out.println(b.method(5));
    }

}