Programming and Problem Solving with Java

CASE STUDY

562

MERGING ADDRESS BOOKS

Problem:In earlier chapters we created an electronic address book in which each entry

contains a name, an address, a phone number, and a birthday. We have stored the

entries on a file of objects. The electronic address book has been so successful that we

have shared it with others. Now we want to combine the entries from two address

books and print address labels in alphabetical order. If the same name appears in both

address books, the appropriate label should be printed only once. We also want to save

the combined address books.

Brainstorming:The processing seems very straightforward. We create a new address

book object made up of all the entries in both address books, removing duplicate

entries along the way. The combined address book must then be sorted and labels

printed on a text file. In addition to the classes involved in the class Entry, we have

three instances of an object file (two input and one output), a text file, and a driver:

Filtering:To this point, we have been working with files. The restriction that the list of

labels be alphabetized may lead to a different solution. We could read the two files of

entries and store them into two SortedListobjects. Then we could merge the two lists

and the output would be sorted. Let’s revise our list of classes:

Determining Responsibilities:This problem is somewhat different in that all of the

responsibilities are in the driver, and they are clearly spelled out in the problem

description. At this point, we switch from an object-oriented view and look at the tasks

ObjectInputStream

ObjectOutputStream

PrintWriter

SortedList

Driver

ObjectInputStream

ObjectOutputStream

PrintWriter

Driver