Phone Contacts App

Introduction

For this activity, you'll be building a simple version of a phone contacts app, similar to what you might use on your own phone!

The contacts app has the ability to add contacts with their name, phone number, and email address. You can view all of your contacts sorted by their first or last name in ascending or descending order. You can also view a sublist of your contacts based on their name -- for example, if you have lots of contacts, you can jump forward to a person in the middle of your contacts list and view all the contacts after them.

The app has some APIs to support this functionality.

• AddContact: Saves the given contact.
• GetContacts: Retrieves all contacts in the provided sort order. If no sort parameters are given, returns the default of sorting by last name in ascending order.
• ClearContacts: Removes all contacts.
• GetContactsStartingAt: Retrieves a portion of contacts starting at Name and includes all the contacts after the given Name

We've also created some internal models used for creating contacts and sorting:

• Contact
  • Name name
  • String phoneNumber
  • String email
• Name
  • String firstName
  • String lastName
• SortBy (enum)
  • FIRST_NAME, LAST_NAME
• SortOrder (enum)
  • ASCENDING, DESCENDING

The code base follows the Activity-DAO pattern that we've come to know and love. The various Activity classes each implement one operation that our service supports. All activities depend on ContactDao's methods to accomplish their use cases.

Disclaimer: One difference that you'll notice here is that our Activity classes don't yet accept/return Response/Result objects. They're accepting/returning individual values or internal model objects. We'll keep our activities like this until we create our service infrastructure and the necessary models. That retrofit is beyond the scope of this activity.

Phase 1: Update ContactDao to support AddContact, GetContacts, ClearContacts

The activity classes for AddContact, GetContacts, and ClearContacts have all been implemented, but we need to complete their corresponding Dao methods to get the basic functionality of the app working! We encourage you to look at TreeMap's and Comparator's Javadocs to see what methods can help provide the required functionality.

1. Instantiate TreeMaps contactsSortedByFirstName and contactsSortedByFirstName in ContactDao's constructor to support sorting contacts by first name and last name.
   1. You'll need to provide a Comparator to the TreeMaps for them to know how to order the names.
2. Implement ContactDao::getContacts to retrieve contacts in the requested sort order
   1. You'll see that the method takes in SortBy and SortOrder enums as parameters. Make sure that the map you return is sorted based on these parameters.

You do NOT need to implement ContactDao::getContactsStartingAt yet. (That's in the next phase!)

Phase 1 is complete when:

• You have created TreeMaps in ContactDao's constructor for sorting contacts by first name and last name
• You have implemented ContactDao::getContacts
• Phase0Test and Phase1Test tests pass.

Hints

• How can I sort by first name and last name?
• How do I get the contacts in descending order?

Phase 2: Implement GetContactsStartingAt

In some cases, we may want to get a subset of our contacts. For example, if you have lots of contacts, you may want to jump forward to a person in the middle of your contacts list and view all the contacts after them.

Implement ContactDao::getContactsStartingAt. Like getContacts, getContactsStartingAt accepts SortBy and SortOrder parameters, but it also takes accepts a Name startkey. The method should return the portion of contacts that includes startKey and all contacts that come after startKey in the requested sort order.

For example, let's say you have four contacts, with names:

• Jane Doe
• Michael Smith
• Alice White
• Tom Young

(This list is sorted in ASCENDING order by LAST_NAME)

If you called getContactsStartingAt("Alice White", SortBy.LAST_NAME, SortOrder.ASCENDING)

The operation should return the contact information for Alice White and Tom Young, in that order.

Alternatively, say you called getContactsStartingAt("Michael Smith", SortBy.FIRST_NAME, SortOrder.DESCENDING)

The descending list sorted by first name looks like:

• Tom Young
• Michael Smith
• Jane Doe
• Alice White

So the operation should return the contact information for Michael Smith, Jane Doe, and Alice White, in that order.

Take a look at TreeMap's Javadoc to find methods that can do what you need!

Phase 2 is complete when:

• You have implemented ContactDao's getContactsStartingAt
• Phase2Test tests pass

Hints

• How do I only retrieve part of a TreeMap?

Extensions

• Add a RemoveContact operation to remove a specific contact
• Enhance the GetContactsStartingAt activity so that it returns contacts in between two provided names
• Determine the Big-O runtime complexity of each method in ContactDao and add that information to each method's javadoc.