CSCI3901-Lab 4 Exceptions and Assertions Solved

In this lab, you will practice using exceptions and assertions.

you will create two small programs that demonstrate how to use exceptions and assertions.

Preparation
•    Review the discussion on exceptions from class.

•    Review the recursive code for calculating the Fibonacci numbers from the debugging lab.

•    Prepare pseudocode to implement a non-recursive binary search on an array of integers.

Procedure
Set-up

1. Get the recursive code for calculating the Fibonacci numbers working in a project.

Lab steps

Part 1 - Exceptions
1.   Revise the Fibonacci code as follows to be able to limit the depth of the recursion:

•    Add two parameters to the method: one to say the maximum number of levels of recursion should be allowed and the second to say how deep you are now in the recursion

•    When the code calls itself recursively, increment the parameter on how deep you are into the recursion

2.   Create a custom-made exception called MaximumRecursionDepth that extends the RuntimeException class. The new exception should include a String message and an int that is the depth of recursion reached. Ensure that your custom-made exception has two methods available:

•    getMessage() to return the string message

•    getDepth() to return the integer depth that was reached at the time of the exception

3.   Modify your Fibonacci code to throw a MaximumRecursionDepth exception when the recursion depth exceeds the value of the parameter for the maximum number of levels of recursion.

1

Part 2 - Assertions
1.   Write (non-recursive) code to perform a binary search on a sorted array. You can get help from the Internet for this part; just be sure to cite any sources that you use. This step is not the critical one of the lab.

2.   Add the following assertions:

•    a loop precondition

•    a loop invariant

•    a postcondition

3.   Ensure that your assertions are working.

Questions
We usually want you to re-use existing code and infrastructure whenever possible. Why might you create your own exception?

We added parameters to the Fibonacci method. However, those parameters aren’t very meaningful to a general user. What would you do to the code to make it more accessible for a general user?

How would you recommend for someone to develop a loop invariant?

How can loop invariants help you in programming, even if you don’t include them directly as assertions in your code?

Reporting
1.   In one file, list

•    The members of your team.

•    The answers from the Questions section of the lab.

2.   Generate a PDF from the document.