@Override
    public Trade[] getTrades() {
        String resultRequest;
        if (previews != null) {
            resultRequest = HttpUtils.httpGet(url + "trades/RON/?since_time=" + previews.getTimestamp());         
            JSONArray arr = JSONArray.fromObject(resultRequest);
            if (arr.isEmpty()) {
                return null;
            }
        } else {
            resultRequest = HttpUtils.httpGet(url + "trades/RON/?since_time="
                    + ((System.currentTimeMillis() / 1000L) - 86400 * 7));
            JSONArray arr = JSONArray.fromObject(resultRequest);
            if (arr.isEmpty()) {
                return null;
            }
        }
        if (resultRequest != null) {
            try {
                BtcXChangeTrades t = new BtcXChangeTrades(this);
                try {
                    t.getAllTrades(resultRequest);
                } catch (TradeDataNotAvailableException ex) {
                    Logger.getLogger(BtcXChange.class.getName()).log(Level.SEVERE, null, ex);
                }
                if (t.getArrayTrades().length > 0) {
                    previews = t.getArrayTrades()[t.getArrayTrades().length - 1];
                    return t.getArrayTrades();
                }
            } catch (ExchangeException ex) {
                Logger.getLogger(BtcXChange.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
        return null;
    }