public List queryDataList()

in empire-db/src/main/java/org/apache/empire/db/DBUtils.java [823:883]
50 lines of code
15 McCabe index (conditional complexity)

    public <T extends DataListEntry> List<T> queryDataList(DBCommandExpr cmd, DataListFactory<T> factory, int first, int pageSize)
    {
        List<T> list = null;
        DBReader r = new DBReader(context);
        try
        {   // prepare
            factory.prepareQuery(cmd, context);
            // check pageSize
            if (pageSize==0)
            {   log.warn("PageSize must not be 0. Setting to -1 for all records!");
                pageSize = -1;
            }
            // set range
            DBMSHandler dbms = context.getDbms();
            if (pageSize>0 && dbms.isSupported(DBMSFeature.QUERY_LIMIT_ROWS))
            {   // let the database limit the rows
                if (first>0 && dbms.isSupported(DBMSFeature.QUERY_SKIP_ROWS))
                {   // let the database skip the rows
                    cmd.skipRows(first);
                    // no need to skip rows ourself
                    first = 0;
                }
                cmd.limitRows(first+pageSize);
            }
            // Runquery
            r.open(cmd);
            if (first>0) 
            {   // skip rows
                r.skipRows(first);
            }
            // Create a list of data entries
            int maxCount = (pageSize>=0) ? pageSize : MAX_QUERY_ROWS;
            list = factory.newList((pageSize>=0) ? pageSize : 10);
            // add data
            int rownum = 0;
            while (r.moveNext() && maxCount != 0)
            {   // Create bean an init
                T entry = factory.newEntry(rownum, r);
                if (entry==null)
                    continue;
                // add entry
                list.add(entry);
                rownum++;
                // Decrease count
                if (maxCount > 0)
                    maxCount--;
            }
            // check
            if (rownum==MAX_QUERY_ROWS)
                queryRowLimitExeeded();
            // done
            return list;
        }
        finally
        {   // close reader
            r.close();
            // complete
            if (list!=null)
                factory.completeQuery(list);
        }
    }