Give a very good method to count the number of ones in a "n" (e.g. 32) bit number.

public class Count {
 public static void main(String args[])
  {
   int count=0;
      int num=1101011011;
        for(int i=0;i<6;i++)//统计的位数
   {
    if(num%Math.pow(10,i+1)==Math.pow(10,i))
     count++;  
    num=(int) (num-num%Math.pow(10,i+1));
    
   }
   
   System.out.print(count);
   
  }
  
 }