java中实现递归计算二进制表示中1的个数

借助Java语言，运用递归算法计算整数N的二进制表示中1的个数

 
public class CalculateNumberInBinaryexpression {
  //Main method.
  public static void main(String[] args) {
     
    //For example ,make N equals 13 ,the result shows 3
    System.out.println(numOfEven(13));
     
    //For example ,make N equals 128 ,the result shows 1
    System.out.println(numOfEven(128));
  }
   
  //The static method of numOfEven is the recursive method.
  public static int numOfEven(int x) {
     
    //The base of recursive.
    if(x==0) {
      return 0;
    }
     
    //If x is an odd.
    else if(x%2!=0) {
      return numOfEven(x>>1)+1;
    }
     
    //If x is an even except 0.
    else {
      while(x%2==0) {
 x=(x>>1);
      }
      return numOfEven(x);
    }
  }
}

来个最简单的，不过未测试：）

public int a(int i){
    if(i==0||i==1) return i;
    return i%2+a(i/2);

}

以上所述就是本文的全部内容了，希望大家能够喜欢。