factorial.java

介绍了java的一些应用

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package 计算阶乘之和;
import java.io.*;
/**
 *
 * @author liuwei
 */
public class Factorial {
    private int N;
    private long sum;
    public Factorial(int n)
    {
        N=n;
        sum=0;
    }
    public static void main(String[] args)
    {
        Factorial fac=new Factorial(1);//N赋初值为1
        int i;
        int tem=1;
        System.out.println("Please input the max number N:");
        try{BufferedReader br=
                    new BufferedReader (new InputStreamReader(System.in));
            fac.N=Integer.parseInt(br.readLine());
            }catch(IOException e){}
        for(i=1;i<=fac.N;i++){
            tem*=i;
            fac.sum+=tem;
        }
        System.out.println("1！+2！+…..+"+fac.N+"！=:"+fac.sum);
    }

}