Hands On Java: Project 5

Objectives

1. Practice designing a solution to a problem;
2. Practice using Java selective and repetitive behavior;
3. Practice writing methods; and
4. Practice writing reusable code.

Introduction

Your instructor will assign you one of the following problems. To solve your problem, write a program that inputs the necessary information to compute and output the indicated values, as efficiently as possible. Use object-centered design, following the example in the lab exercise, and then employ stepwise translation to encode your algorithm in Java. Use methods and separate module classes where appropriate to make your code reusable. Then test your program thoroughly, using the facilities at your disposal.

Projects

5.1. Write a program that asks the user how many test scores they have, and then reads that many test scores, averages them, and displays the average and a pass/fail grade appropriate for that average (passing is 60 or higher, failing is below 60). Use a module method to average the input values.

5.2. Write a "password protection" method that you can use to guard your programs. When called, this method should ask the user for a password. It should allow the user N tries at entering the correct password, where N is a value received from its caller.. If the user enters the correct password, the method returns control to its caller, where execution proceeds as normal. If the user fails to enter the correct password after N tries, then the method should use System.exit(1) to terminate the program. Store your method in a separate module class, so that different programs can share it.

5.3. Proceed as in 5.1, but instead of displaying a pass/fail grade, the program should compute a "normal" letter grade (90-100 = A, 80-89 = B, 70-79 = C, 60-69 = D, ...).

5.4. Write two methods:

• sum(n) that computes the value (1 + 2 + ... + (n-1) + n)
• factorial(n) that computes (1 * 2 * ... * (n-1) * n)

Your methods should check the value of n is positive; if not, they should display an informative error message and return 0.

Store them in a separately compiled module. Write a driver program that lets the user apply either of these methods to an input value, displaying the result.

Turn In: A hard copy of this grade sheet, attached to hard copies of

1. your design for this project;
2. all source files you create for this project; and
3. the output from an execution of your program.

Don't forget to clean up when you are all finished...

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