Java - return a reference to a specific place in a linkedlist with list iterator

Question

I have a Portfolio class that also has linkedlist of Investment class (example - Google is an instance of Investment), each investment has a trade history (another linked list) with data for each trade.

When the user want to make a trade (buy google stocks for 5K) I need to find if the investment (in google) already exists in the investmentsList. If it doesn't - add new investment (and add the trade for its trade history), If it does - just add another link to google's tradeHistory linkedlist.

The problem - I need findInvestment method to return a reference to google (investment instance) from the investmentList so I can update its trade history.The method returns a listIterator rather than a reference to a location in investmentList(should be Investment Class). How should I correct findInvestment? (found=iter is wrong)

public class Portfolio {


private LinkedList<Investment> investmentsList;

public Portfolio() {
    investmentsList = new LinkedList<Investment>();
}

public void addInvestment(String symbol, double money){

    Investment invest = findInvestment(symbol);
    if (invest == null) {
        System.out.println("symbol does not exist");
        getInvestmentsList().add(new Investment(symbol,money));
        System.out.println("New invetment has been added to your portfolio - " +symbol);
    } else {
        invest.addTrade(symbol,money);
        System.out.println("A new trade has been added to the current investment - " + symbol);

    }
}

public Investment findInvestment(String symbol){

    Investment found = null;
    ListIterator<Investment> iter = investmentsList.listIterator();


    while (iter.hasNext()) {

       if (iter.next().getSymbol().equals(symbol)) {
            found = iter;
            return found;
            System.out.println("Found the symbol");
        }
    }

    return found;
}

Answer 1

Simply hold an Investment - or in java 8 Optional<Investment>

Instead of the linked list:

private Map<String, Investment> investmentsBySymbol;

public Investment findInvestment(String symbol){
    Investment found = investmentsList.get(symbol);
    return found;
}

Also BigDecimal is a better choice than double as

new BigDecimal("3.10");

has a precision of 2, and doubles are always inprecise.