This page lists various changes that might be made to the system. Modifying the various documents and program to incorporate one or more of these changes would make an interesting exercise for the reader. They are listed in order of estimated increasing difficulty.

• The Print Mailing Labels Use Case prints all the information about a person in "mailing label" format. Of course, a phone number doesn't appear on a mailing label. A new use case (perhaps called Print All) might be added that prints all information.
   
• Another piece of information that might be valuable to store about a person is the individual's email address. Adding this would require including this information in the relevant use cases (Add, Edit, Print All, Find/Find Again). (Of course, if a Labels Use Case were added, the email address would not be included in it.)
   
• It was noted in the orginal requirements that the program might be modified to allow multiple address books to be open at the same time - each in its own window. This might entail the following changes:
   
  • The Create New Address Book and Open Existing Address Book Use Cases would no longer close the current address book. Instead, they would create a new copy of the GUI, with its own address book (either a newly created, empty one, or one read from a file specified by the user.) There would thus be two (or more) windows visible on the screen.
     
  • A new Close Address Book Use Case would be added to allow the user to close a single window (and its associated address book). This could be initiated by a new Close option in the File menu, or by clicking the close box for the window. It would offer to save changes, if necessary, and then close the window. If the window that is closed is the last open window in the program, then the program should be terminated as well; otherwise, the program would continue running with the remaining window(s) visible.
     
  • The code that is activated when the close box for the window is clicked would be the Close Address Book Use Case described above, instead of the Quit Program Use Case.
     
  • The Quit Program Use Case (activated from the Quit item in the File menu) would need to cause all open windows to be closed, with appropriate offers to save changes, unless the user cancels the operation for any window. If the user cancels the save for any window, the entire use case would terminate at once, without attempting to close additional windows.
     
• The existing searching facility looks for persons that contain a given value in one of their fields - e.g. a search for "son" would find persons named Johnson, Peterson, ... as well as individuals living in Johnson City, Tennessee ... An alternative would be a search that looks for an exact match between the search criterion and the value contained in some field - e.g. a search for "Johnson" would find a person named "Johnson" but not person living in "Johnson City", though a search for "Buffalo" would find both Bill Buffalo and a person living in Buffalo, NY, since in the first case the last name field contains an exact match for the desired value, and in the second case the city field does. A facility might be added that allows a user request such searches; in this case "Find Text Again" might continue the last type of search that was requested (contains or exact match.)

Some good practice in working with UML might come by modifying the various design documents (beginning with the use cases), not just changing the code.