code: public void combine(SearchFilter new_filter, int op) throws DBException
      {
  
          // cast down to OJBSearchFilter
          OJBSearchFilter ojbFilter = (OJBSearchFilter) new_filter;
  
          switch (op)
          {
  
              case OR:
                  {
                      criteria.addOrCriteria(ojbFilter.getCriteria());
                      break;
                  }
  
              case AND:
                  {
                      criteria.addAndCriteria(ojbFilter.getCriteria());
                      break;
                  }
  
              default:
                  {
                      throw new DBException();
                  }
          }
      }
docs: Combine one other search filters with this one, using the specific operator.
  
  @param new_filter is the SearchFilter class to be combined
  @param op is the logical operator to be used to combine the filters
  @exception DBException