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public class XmlStockListDAO implements StockListDAO {
    
    protected static StockList stockList = null;
    protected  String filename = "c:/cw1/stockList.xml";
    
    /** Creates a new instance of XmlStockListDAO */
    public XmlStockListDAO() {
        if(stockList == null)
        {
            this.loadFile();
        }
    }
    
    public void updateStockList(StockList stockList) {
        this.saveFile();
    }
    
    public StockList loadStockList() {
        return stockList;
    }
    
    public void loadFile() {
        Object o = XmlHelper.loadFromFile(filename);
        if(o == null) {
            stockList = new StockList();
        } else {
            stockList = (StockList) o;
        }
    }
    
    public void saveFile() {
        XmlHelper.saveToFile(stockList, filename);
    }
    
}