SWEN20003
Object Oriented Software Development
Workshop 10
Eleanor McMurtry
Semester 1, 2002
Workshop
This week, we are reviewing exceptions and testing.
1. Exceptions are the standard Java way to handle runtime errors. They may be either unchecked (such
as null references, array overflows, division by zero) or checked (such as IO errors).
2. Checked exceptions must be either caught or declared in the method header with the “‘throws” keyword.
3. Exceptions fill a similar role to return codes in C (e.g. for malloc).
4. Automated testing makes it easier to detect regressions (when a new feature breaks an existing one)
among other things.
5. A unit test tests a single unit (e.g. method or class).
Questions
1. Create a CsvException class to represent errors that may occur when handling comma-separated value
(CSV) data. It should inherit from “Exception”, and should contain a descriptive message. For example,
you may choose to include a file name.
2. Create the following exception classes inheriting from CsvException; they should have their own descrip-
tive messages.
(a) TooManyEntriesException: when a row has more entries than the header row
(b) NotEnoughEntriesException: when a row has fewer entries than the header row
(c) UnmatchedQuoteException: when a quotation mark ” at the start of an entry is not matched by a
quotation mark at the end of the entry
3. Using the above exception classes, write a method
List
that reads a CSV file and returns its contents as a two-dimensional ArrayList. The outer dimension
should be the rows of the file, and the inner dimension should be the entries within each row. If any of
the above exceptional cases are encountered, you should throw the appropriate exception.
4. Write JUnit test cases for the CSV reader. You should test the correct case with the below test case:
student,mark
Alice,90
Bob,65
Carol,72
Write one unit test for each of the possible exceptions. Hint: use this annotation when an exception is
expected:
@Test(expected=NotEnoughEntriesException.class)
1