private synchronized static void doUpdate() {
        System.out.println("updating");
        StockStorage store = StockStorage.getInstance();
        ArrayList<String> identifierList;
        ArrayList<Stock> stockList;
        HashMap<String, Float> priceMap;
        
        identifierList = store.getAllIdentifier();   
        stockList = StockQuery.QueryMultiple(identifierList);
        store.setPriceForMultiple(stockList);
    }