the level is limited.
I don't know what kind of efficient solution you want, but I tried it myself. In python, what I think should be efficient is actually not efficient. Instead, I think the stupidest method is more efficient.

public static List<Integer> getBitCollections (long bits) {  
    List<Integer> index = new ArrayList<>();  
 int position = 1;  
 while (bits != 0) {  
    if ((bits & 1) != 0) {  
        index.add(position);  
    }  
      positionPP;  
      bits = bits >>> 1;  
  }  
    return index;  
}