15-121 Homework 2: Simple Contact List - Due 2/5 at midnight

Download and unzip hw2-code.zip, which contains the file Contact.java (based on the Person.java class we used in lacture and a slightly modified Contacts.java that we developed in class on Tuesday. To make it more realistic I have changed the nationality field to andrewID and added some data that would normally be found in a contact entry. All the code that you write for this assignment should be added to one of these two files.

Note: You will be graded in part on your coding style. Your code should be easy to read, well organized, and concise. You should avoid duplicate code.

Background: A Contact List

In this homework, you'll put the finishing touches on a primitive contacts list, using the data in names.txt as an initial dataset. The data in this file consists of a person's first name, last name, andrew ID, phone number (made up most of these), zipcode, and "group". We're not quite ready to compete with Apple, but we should be able to get some reasonable functionality even at this stage of the course.

The Methods

You will need to write the following methods in the Contacts class:

Contacts(String fileName)
This constructor needs to be modified to work with the new data format found in names.txt. It also needs to make sure that everyone's andrew ID is unique and report an error if a duplicate is found while reading the file.

String toString()
Returns a properly formatted (spaced) String that represents the used cells of the contacts array. You will also need to create a toString() for the Contact class.

boolean addContact(Contact p)
If there is room in the contacts array, verifies that the new Contact has a unique andrew ID and, if so, adds Contact p after the current last element, updating numContacts appropriately, and returns true. If not, returns false.

void removeContact(String id)
Removes the entry for the contact with andrew ID, id, from the contact list, if it exists. All the entries after that contact need to be moved up one slot in the array and the number of used entries in the contact array should be decreased by one. If there is no contact with the andrew ID, id, this method should print a message to that effect.

void changePhone(String id, String newNumber)
If a contact with andrew ID, id, exists, changes the phone number that belongs to the contact with that ID to newNumber. If no such contact exists, the method should print a message to that effect.

void allInGroup(String g)
Prints all the entries in the contact array that are in the specified group, g. Prints nothing if no entries match the specified group. You will need to modify the Contact class to add a method that returns a contact's group in order to do this.

void allInZip(int zip)
Prints all the entries in the contact array that have the specified zipcode, zip. Prints nothing if no entries match the specified group. As above, You will need to modify the Contact class to add a method that returns a contact's zipcode in order to do this.

void updateDatabase(String fileName)
Creates a file with name provided by fileName and writes the contents (only the used cells) of the contact list to this file. N.B., Your file must be written so that it can be read back in by your program!

Some of the methods you will write in the Contacts class will require that you change/add methods in the Contact class. Others may require a different getter or setter.

Of course, you will also need to test your methods by calling them from main.

Submitting Your Work

When you have completed the assignment and tested your code thoroughly, create a .zip file with your work (including both Contact.java and Contacts.java). Name the zip file "your-andrew-id".zip and upload it to the HW2 folder on Box.

Make sure to keep a copy of your work just in case something goes wrong!