大数阶乘问题

/*
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 */
package factorial_1;

import java.math.BigInteger;
import java.util.Scanner;

public class Factorial_1 {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        Scanner in = new Scanner(System.in);
System.out.print("请输入一个整数：");
int m = in.nextInt();
BigInteger result = new BigInteger("1");//为result赋初始值，为1
        //BigInteger result = BigInteger.ONE;
for (int i = 1; i <= m; i++) 
        {
            BigInteger num = new BigInteger(String.valueOf(i));
            result = result.multiply(num);//调用自乘方法
}
System.out.print(m+"的阶乘结果是:");
System.out.println(result);//输出结果
System.out.print(m+"的阶乘结果的长度是:");
        System.out.println(String.valueOf(result).length());//输出长度