Java Reference
In-Depth Information
16. selector = selectorPanel;
17. }
18.
19. public void createContact(String firstName, String lastName, String title, String
organization){
20. Contact newContact = new ContactImpl(firstName, lastName, title, organization);
21. addContact(newContact);
22. selector.addContact(newContact);
23. display.contactChanged(newContact);
24. }
25. public void updateContact(String firstName, String lastName, String title, String
organization){
26. Contact updateContact = (Contact)contacts.get(contactIndex);
27. if (updateContact != null){
28. updateContact.setFirstName(firstName);
29. updateContact.setLastName(lastName);
30. updateContact.setTitle(title);
31. updateContact.setOrganization(organization);
32. display.contactChanged(updateContact);
33. }
34. }
35. public void selectContact(Contact contact){
36. if (contacts.contains(contact)){
37. contactIndex = contacts.indexOf(contact);
38. display.contactChanged(contact);
39. editor.setContactFields(contact);
40. }
41. }
42. public Contact [] getAllContacts(){
43. return (Contact [])contacts.toArray(new Contact[1]);
44. }
45. public void addContact(Contact contact){
46. if (!contacts.contains(contact)){
47. contacts.add(contact);
48. }
49. }
50. }
The
ContactMediatorImpl
interacts with each of the panels differently. For the
ContactDisplayPanel
, the
mediator calls its
contactChanged
method for the create, update and select operations. For the
ContactSelectorPanel
, the mediator provides the list of
Contacts
with the
getAllContacts
method, receives
select notifications, and adds a new
Contact
object to the panel when one is created. The mediator receives create
and update method calls from the
ContactEditorPanel
, and notifies the panel of select actions from the
ContactSelectorPanel
.
Memento
Also known as Token, Snapshot
Pattern Properties
Type: Behavioral
Level: Object
Purpose
To preserve a “snapshot” of an object's state, so that the object can return to its original state without having to
reveal its content to the rest of the world.
Introduction
Every application has objects that need to preserve information beyond their lifespan. Often, this relates to shared
data, but what if the private data of an object needs to be preserved? Sending the data to another object is a bad
idea, since it goes against the rules of encapsulation. If you sent data to other objects, they would be able to read
or, even worse, modify the data.
It's like going to a national park where they preserve the moose. The object whose data is being saved is that
moose. You're not allowed to take a moose home with you, but postcards and moose t-shirts are available at the
national park gift shop.
