code: public final int size() {
          int overallSize = 0;
          if (subSets != null) {
              for (int i = 0; i < subSets.length; i++) {
                  overallSize = overallSize + subSets[i].size();
              }
          }
          return overallSize;
      }
docs: /*
  (non-Javadoc)
  
  @see java.util.Collection#size()