Exercise : jGRASP Debugger

The debugger can help you learn how classes and objects work. In this exercise we will debug the Ch. 8 "Stock" Case Study example. This program tracks purchases of two stock investments. To download the example:

Go to the class web page and click the "Textbook" link.
Find the section labeled "Code Files" and click the "code files" link. Then click "ch08".
Download and save the files Stock.java and StockMain.java. Right-click each file name and Save the Link in the same folder you use for lab work.
Compile and run StockMain.java in jGRASP to see that it works.

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Exercise - jGRASP Debugger

Set a stop on the System.out.print on line 53, and debug the program.

Type the user input to recreate the following partial log:

First stock's symbol: AMZN
How many purchases did you make? 2
1: How many shares, at what price per share? 50 35.06
2: How many shares, at what price per share? 25 38.52

At this point, what are the values of the fields in the currentStock object?
(Ask a TA if you need help.)
totalShares
75
totalCost
2716.0

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Exercise - jGRASP Debugger

Now let's debug inside one of the Stock object's methods. Your program should still be stopped. Set a new stop at the return on line 29 of Stock.java.
Resume your program . It will prompt for today's price per share. Enter 37.29 . If you did it properly, the program should now call getProfit on the Stock and hit your stop point.
```
What is today's price per share? 37.29
```
What are the values of the object (this) 's fields, and the variable marketValue ?
symbol
"AMZN"
totalShares
75
totalCost
2716.0
marketValue
2796.75

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Exercise - jGRASP Debugger

Now let's watch the total shares and cost of a stock change with each purchase. Remove your existing stop points and set a new stop somewhere in the for loop on lines 42-50 of StockMain, and Resume .

Type the user input to continue recreating the following partial log:

Second stock's symbol: INTC
How many purchases did you make? 3
1: How many shares, at what price per share? 15 16.55
2: How many shares, at what price per share? 10 18.09
3: How many shares, at what price per share? 20 17.05
What is today's price per share? 17.82

After each call of purchase, what are the field values of currentStock?

field	after 1st purchase	after 2nd	after 3rd
`totalShares`	15	25	45
`totalCost`	248.25	429.15	770.15

`symbol`		"AMZN"
`totalShares`		75
`totalCost`		2716.0