code: public static int ofSetBits32_1(int i) {
          i = i - ((i >>> 1) & 0x55555555);
          i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
          i = ((i + (i >>> 4)) & 0x0F0F0F0F);
          return (i * (0x01010101)) >>> 24;
      }
docs: Count number of bits set to one in the given int (32-bit integers).
  @param i
  @return