The 'personal address book' application program enables users to manage their contact information through a command-line interface, separating the UI from internal processing. Key components include a contact manager for adding and deleting contacts, a contact finder for searching, and a data manager for saving and loading information. The document requests explanations and diagrams related to the system's design and user interaction.

1. A "Personal Address Book" application program allows the user to add, delete, search, save and
load her contact information. The program separates user (command-line) interface and internal
processing subsystem. The internal processing system consists of the following classes:
ContactManager (responsible for add and delete operations), ContactFinder (responsible for
search operation), and DataManager (responsible for save and load operations). 1-Explain how
you will design the user interface using the Facade pattern? Illustrate your answer using class
diagram for the entire system. 2- Draw an UML sequence diagram to show the behavioural view
of the personal address book program that demonstrates what happens when a user enter a new
contact information.