Email Lab

Using Sets and Maps to Create

An Email Directory

Introduction

In this lab you will complete a class EMDirectory that stores email addresses as strings. An email address can recognized because it must have the character '@'. Any string without this character is considered an alias or name under which one or more items are stored in a set. Each item stored under an alias is an email address or another alias. For simplicity aliases (names) are limited to a string with no spaces.

For example, the alias ChrisNevison may have stored under it the set containing the single email [chris@cs.colgate.edu] and the alias Jamie may have the set [jscovern@mail.colgate.edu]. On the other hand, the alias CS102 may have the set [Jamie, Leana, Oliver, Andrew, David, Frank, Montek, Steve, Victor, Brendan] stored under it. A set can have a mix of email addresses and other aliases stored. For example, CSFaculty may have the set [ChrisNevison, BarbaraCloud, pmulry@mail.colgate.edu, tparks@mail.colgate.edu].

Specifications

The starting code is in the zip file emailLab.ZIP. The EMDirectory class is already started and you are to implement the following methods:

• addEntry                takes an alias and another string (email or alias) and stores the second string in the set associated with the alias.
• removeEntry          takes an alias and another string (email or alias) and removes the second string from the set associated with the alias;
                                if the second string is not stored under this alias, or the alias is not in the map, no changes are made and an
                                appropriate message is printed. If after removal, the set stroed under this alias is empty, then the alias should be
                                removed from the directory.
• expandEmails        takes an alias and returns a set of all emails stored under that alias and under aliases under that alias, etc. Only emails,
                                no aliases are in the set that is returned. (Hint: think recursion.)
• toString                 returns a string that has one line for each key (alias) in the directory followed by the items in the set stored under that
                               key (aliases, not expanded, and emails)

To Do

Complete the code for the class EMDirectory.

Extra credit:

Modify the expandEmails method so that it will still work even if the directory has cycles in it.

If you want to experiment with a GUI, see if you can create a simple GUI for this program using the Java swing package.