code: public static Boolean not(Boolean bVal) 
    {
  //    return notTable[lookupValue];
      if(bVal == null)
        return null;
      else if (bVal.equals(Boolean.TRUE))
        return Boolean.FALSE;
      else if (bVal.equals(Boolean.FALSE))
        return Boolean.TRUE;
      else return null;  
      
    }
docs: Perform logical 'not' on a Boolean instance