项目一----整数和。偶数和。阶乘和。

public class Sumn {public static void main(String args[]){System.out.println("整数和");Sum s1=new Sum();s1.print();System.out.println("偶数和");Sumn1 s2=new Sumn1();s2.print();System.out.println("阶乘和");Sumn2 s3=new Sumn2();s3.print();} }public class Sum {int sum=0;int n; public int sum(int n){int x=0;for(int i=1;i<=n;i++){x=x+i;}    int s=x;return s;}public void print(){System.out.println(sum(10));}}public class Sumn1 {int sumn=0;int n;public int sumn(int n){int x=0;for(int i=2;i<=n;i=i+2){x=x+i;}    int s=x;return s;}public void print(){System.out.println(sumn(10));}}public class Sumn2 { public int sumn2(int n){int x=1;for(int i=1;i<=n;i++){x=x*i;}    int s=x;return s;}public void print(){System.out.println(sumn2(10));}}