java实现找一个数范围内所有的一

//FindOne.java 
package com.minirisoft;
import java.util.Scanner;
public class FindOne {
	public static int Sum( int n )  
    {  
       int Count = 0;  
       int Factor = 1;  
       int Lower = 0;  
       int Curr = 0;  
       int Higher = 0;  
       while( n / Factor != 0 )  
       {  
         Lower = n - ( n / Factor ) * Factor;  
         Curr = (n / Factor ) % 10;  
         Higher = n / ( Factor *10 );        
         switch( Curr )  
         {  
            case 0:  
                Count += Higher * Factor;  
                break;  
            case 1:  
                Count += Higher * Factor + Lower + 1;  
                break;  
            default:  
                Count += ( Higher + 1 ) * Factor;  
                break;  
            }  
         Factor *= 10;  
       }  
         return Count;  
    }  
	public static void main(String[] args)
    {
        Scanner input=new Scanner(System.in);
        System.out.print("请输入一个正整数：");
        int n=input.nextInt();
	    System.out.print("1到"+n+"的1个数为："+Sum(n)+"个");
    }   
}