/** * Adds the specified element to this set if it is not already present and the element >= 0. * * @param e element to be added to this set * @return <tt>true</tt> if this set did not already contain the specified element and the element * >= 0 */ @Override public boolean add(Integer e) { if (e < 0) throw new RuntimeException("To add a negative number: " + e); if (contains(e)) { return false; } int wordIndex = wordIndex(e); expandTo(wordIndex); words[wordIndex] |= (1L << e); ++size; ++modCount; return true; }