Inheritance and Interfaces - Building Java Programs: A Back to Basics Approach - page 606

30 // the stock at the given price per share
31 public void purchase( int shares, double pricePerShare) {
32 totalShares += shares;
33 addCost(shares * pricePerShare);
34 }
35 }
The MutualFund class receives similar treatment, but with a double for its total
shares (the two classes are highly redundant; we'll improve them in the next section):
1 // A MutualFund object represents a mutual fund asset.
2 // Initial version.
3 public class MutualFund extends ShareAsset implements Asset {
4 private double totalShares;
5
6 // constructs a new MutualFund investment with the given
7 // symbol and price per share
8 public MutualFund(String symbol, double currentPrice) {
9 super (symbol, currentPrice);
10 totalShares = 0.0;
11 }
12
13 // returns the market value of this mutual fund, which
14 // is the number of shares times the price per share
15 public double getMarketValue() {
16 return totalShares * getCurrentPrice();
17 }
18
19 // returns the number of shares of this mutual fund
20 public double getTotalShares() {
21 return totalShares;
22 }
23
24 // returns the profit made on this mutual fund
25 public double getProfit() {
26 return getMarketValue() - getTotalCost();
27 }
28
29 // records purchase of the given shares at the given price
30 public void purchase( double shares, double pricePerShare) {
31 totalShares += shares;
32 addCost(shares * pricePerShare);
33 }
34 }