code: public void setStrength(int value) {
          int noStrength = options & ~STRENGTH_MASK;
          switch(value) {
          case Collator.PRIMARY:
          case Collator.SECONDARY:
          case Collator.TERTIARY:
          case Collator.QUATERNARY:
          case Collator.IDENTICAL:
              options = noStrength | (value << STRENGTH_SHIFT);
              break;
          default:
              throw new IllegalArgumentException("illegal strength value " + value);
          }
      }
docs: except that this class uses bits in its own bit set for simple values.