CSC232: Introduction to CS II
Homework Assignment # 4
Due: Beginning of class on Monday, October 31, 2011.

When a share of common stock of some company is sold, the capital gain (or, sometimes, loss) is the difference between the share's selling price and the price originally paid to buy it. This rule is easy to understand for a single share, but if we sell multiple shares of stock bought over a long period of time, then we must identify the shares actually being sold. A standard accounting principle for identifying which shares of a stock were sold is to use a FIFO protocol --the shares sold are the ones that have been held the longest (indeed, this is the default method built into several personal finance software packages). For example, suppose we buy 100 shares at  $20 each on day 1, 20 shares at $24 on day 2, 200 shares at $36 on day 3, and then sell 150 shares on day 4 at $30 each. Then applying the FIFO protocol means that of the 150 shares sold, 100 were bought on day 1, 20 were bought on day 2, and 30 were bought on day 3. The capital gain in this case would therefore be 100^.10 + 20^.6 + 30^.(-6), or $940. Write a program that takes as input a sequence of transactions of the form "buy x share(s) at $y each" or "sell x share(s) at $y each," assuming that the transactions occur on consecutive days and the values x and y are integers. Given this input sequence, the output should be the total capital gain (or loss) for the entire sequence, using the FIFO protocol to identify shares. The program must read input from a text file named in.dat and must send output to stdout (the computer's screen).

Sample input file is as follows:

The corresponding output should be as follows:

Total capital gain is $1660

Another sample input file is as follows:

Its corresponding output should be as follows:

Total capital loss is $100

I recommend using an inner class to represent a transaction. Give your program the name CapitalGain.java. All your code must be written in a single file/class with that name (no separate demo class). Make sure to upload an electronic copy of the source file on your csc232 eccentric upload folder in a folder called HW\hw4. Also make sure to turn in a stapled hardcopy of your code on the due date. Your program must follow the problem specifications precisely.