CS 1401 Assignment #10

Date Assigned: Tuesday, November 8, 2005 or Wednesday, November 9, 2005.

Due Date: correspondingly, Tuesday, November 15, 2005, or Wednesday, November 16, 2005, before the beginning of your lab section.

Goals: to learn how to include error-handling mechanisms in an application.

Points: This assignment is worth a total of 20 points. No late assignments will be accepted, but credit will be given for partially completed assignments turned in on time.

Assignment: This assignment builds on your work on Assignment 8. In that assignment, we assumed that the input file exists and that all the entries from the input file have the required format.

Now that you are familiar with exceptions, modify your code in such a way that your program will automatically take care of the following exceptions (both pre-defined and user-defined):

If the input file does not exist, your program should print a a user-friendly error message to the screen, and ask the user to re-enter the file name.
If one of the records lacks a required field, your program should:
- print the corresponding error message to the screen, and
- add, to the output file, a similar error message instead of the value of this field.

Example. If a record does not specify the author, as in:

book
title
Programming and Problem Solving with Java
year
2003
publisher
Jones and Bartlett

your program should do two things:

First, it should send the message
```
Author not specified.
```
to the screen, and
Second, it should place the string AUTHOR NOT GIVEN in the corresponding record in the output file, instead of the actual author's names, so that the resulting record will look as follows:

AUTHOR NOT GIVEN, "Programming and Problem Solving with Java," Jones and Bartlett, 2003.

(So that the user will immediately see that something is missing.)

Comment: in the input file, the fields do not necessarily come in order: we can have author before title, or we can have title before author.

For extra credit: make sure that your program recognizes and takes appropriate care of the following three additional types of errors:

Type 1: extra field
- description: a record contains a field which is not one of the required or optional ones;
- example: in addition to the year when the book was published, there is also a month when it was published;
- how to handle this exception: a reasonable idea is to inform the user about this extra field, and to ignore it in the output file.
Type 2: duplicate field
- description: a record contains two fields marked with the same keyword, e.g., two different lines marked "author":
```
author
Luc Longpre
author
Ann Gates and Vladik Kreinovich
```
- how to handle this exception: a reasonable idea may be to add both names with question marks:
```
Luc Longpre? Ann Gates and Vladik Kreinovich?
```
Type 3: un-typed record
- description: a record does not have an indication of whether it is a book or an article or what;
- how to handle this exception: in some cases, we may determine it from the presence of auxiliary fields; in this case, we should handle this record according to this type;
- example: the field "school" is an indication that this is a PhD thesis, so if there is such a field, we should treat this record as a PhD thesis.

Deliverables: as announced in the labs.