Java数据结构及算法实例：快速计算二进制数中1的个数(Fast Bit Counting)

 
package al; 
public class Countones { 
 public static void main(String[] args) { 
  int i = 7; 
  Countones count = new Countones(); 
  System.out.println("There are " + count.getCount(i) + " ones in i"); 
 } 
  
 public int getCount(int i) {   
  int n; 
  for(n=0; i > 0; n++) { 
   i &= (i - 1); 
  }   
  return n;   
 } 
}