CSCI 1103 Lab08: Stocks as Objects

Material from Eck Ch 5.1-2 is covered in this lab.

Create only one file for this lab, Stock.java. It will contain methods that solve each problem.

Do not modify any of the files provided. Your goal is to write create a Stock.java file that is compatible with the provided files like StockMain.java.

There are a series of testing files with names such as Problem1Tests.java which have tests for methods required in each problem. This will allow you to work on each problem separately.

Below is the structure the Stock.java file which you should create. Each problem corresponds to one method in the file though later problems make use of earlier methods.

public class Stock{

  public static void printInfo(Stock stock);
  // PROBLEM 1
  // Print information on the given stock to the screen. The format should be
  //   Microsoft Corporation (MSFT): price: $79.12 shares: 350
  //   ^^^                    ^^^            ^^            ^^
  //   Name                   Symbol         Price         Number of shares
  // 
  // Note that the price is preceded by a $ and has 2 decimal places
  // of accuracy. This makes printf() a good choice to produce the
  // output.

  public static double buyMore(Stock stock, int moreShares);
  // PROBLEM 2
  // Buy more of the specified stock. The number of additional shares
  // to buy is the parameter moreShares.  Modify stock.numShares to be
  // this amount more. Calculate the cost of the purchase which is the
  // 
  //   cost = -(moreShares * stock.price)
  // 
  // Note that costs are negative while profits are positive. Return
  // the cost.

  public static double sellOff(Stock stock, int lessShares);
  // PROBLEM 2
  // Sell off shares of the specified stock. The number of shares to
  // sell is the parameter lessShares. If the numShares field of stock
  // is smaller than lessShares, the transaction is error and return
  // 0.0 without changing anything about stock.  Otherwise, reduce
  // stock.numShares by lessShares. Calculate the profit which is
  // 
  //   profit = stock.price * lessShares
  // 
  // Return the profit.

}

In Stock.java create 4 public fields for the stock class.

1. name for the name of the company. It is a String
2. price for the price per share. It is a double
3. numShares for the number of shared owned. It is an int
4. symbol for the ticker symbol of the stock. It is a String

Each field should be public and non-static.

Successfully defining the fields and compiling the Stock class should allow the following kind of code to run.

Stock stock = new Stock();
stock.symbol = "GOOGL";
stock.price = 1000.62;
stock.numShares = 500;
stock.name = "Alphabet Inc Class A";

public static void printInfo(Stock stock)

Printing information on a stock is a basic operation that is done by the printInfo() method. It should produce output that looks like the following

Welcome to DrJava. 
> Stock stock = new Stock();
> stock.symbol = "GOOGL";
> stock.price = 1000.62;
> stock.numShares = 500;
> stock.name = "Alphabet Inc Class A";

> Stock.printInfo(stock)
Alphabet Inc Class A (GOOGL): price: $1000.62 shares: 500

The format of the message is broken down as follows.

> Stock.printInfo(stock)
Alphabet Inc Class A (GOOGL): price: $1000.62 shares: 500
^                     ^               ^               ^
stock.name           stock. symbol    stock.price     stock.numshares

printf() is useful here to format the price output to 2 decimal digits of accuracy. Use format specifies appropriate to the types of the other fields.

public static double buyMore(Stock stock, int moreShares)

This method takes two parameters, a stock to purchase and the number of moreShares desired. The method should change the numShares field of stock to be larger by moreShares. It should then return the total cost of the purchase which is the stock price multiplied by moreShares. Since this is a cost rather than a profit, the value returned should be negative.

In the examples below, notice how both stocks have their own numShares which changes as buyMore() is invoked on them.

Welcome to DrJava. 
> Stock stock = new Stock();
> stock.symbol = "GOOGL";
> stock.price = 1000.62;
> stock.numShares = 500;
> stock.name = "Alphabet Inc Class A";
> double cost = Stock.buyMore(stock, 1);
> cost
-1000.62
> stock.numShares
501

> Stock other = new Stock();
> other.symbol = "KMON";
> other.price = 25.00;
> other.numShares = 100;
> other.name = "Kauffmoney Inc";

> cost = Stock.buyMore(other, 10);
> cost
-250.0
> cost = Stock.buyMore(other, 10);
> cost
-250.0
> other.numShares
120

> Stock.printInfo(stock)
Alphabet Inc Class A (GOOGL): price: $1000.62 shares: 501
> Stock.printInfo(other)
Kauffmoney Inc (KMON): price: $25.00 shares: 120

public static double sellOff(Stock stock, int lessShares)

As some folks buy stock, others must sell it leading to the sellOff() operation. This method should alter the numShares field to decrease it by the argument lessShares. The profit made from selling the stock is returned which is the stock's price multiplied by the lessShares sold.

There is one exceptional case. In some cases, stock traders mistype orders which can lead to erroneous sales of too much stock at once. One such case that is easy to check is to ensure that if lessShares is larger than the numShares available for the given stock. In this case, ignore the request: do not change numShares and return a profit of 0.0.

Examples are below:

Welcome to DrJava. 
> Stock stock = new Stock();
> stock.symbol = "GOOGL";
> stock.price = 1000.62;
> stock.numShares = 500;
> stock.name = "Alphabet Inc Class A";

> double profit = Stock.sellOff(stock, 1);
> profit
1000.62
> stock.numShares
499
> profit = Stock.sellOff(stock, 99);
> profit
99061.38
> stock.numShares
400

> Stock other = new Stock();
> other.symbol = "KMON";
> other.price = 25.00;
> other.numShares = 100;
> other.name = "Kauffmoney Inc";

> profit = Stock.sellOff(other, 50);
> profit
1250.0
> other.numShares
50

// Attempt to sell of more stock than availble: no effect
> profit = Stock.sellOff(other, 200);
> profit
0.0
> other.numShares
50

> Stock.printInfo(stock)
Alphabet Inc Class A (GOOGL): price: $1000.62 shares: 400
> Stock.printInfo(other)
Kauffmoney Inc (KMON): price: $25.00 shares: 50

You should feel free at any time to get help from lab staff as you get stuck on the exercises.

By the end of the lab, make sure to demonstrate your code to a staff member. This will ensure that you receive full credit on the lab. Staff might ask you to

• Change what is printed
• Compile and run on the command line
• Run tests in DrJava or on the command line
• Show how to zip the folder with your programs in it

Be ready to do any or all of these.

Ensure that file PARTNERS.txt has your name and the name of your partner in it. This fill is located with the other Java files for the lab and can be edited with DrJava.

Once your are confident your code is working, you are ready to submit. Ensure your folder has all of the required files. Create a zip archive of your lab folder and submit it to blackboard.

On Canvas:

• Click on the Assignments section
• Click on the appropriate link for this lab
• Scroll down to "Attach a File"
• Click "Browse My Computer"
• Select you Zip file and press OK